Class 8 Middle School Geography

Chapter 11 Oceania

Oceania:

The smallest continent of the world Oceania is a continent of oceanic islands. It consists of ten thousand islands floating in the Pacific Ocean. The word ‘Oceania’ is derived from the word ‘ocean’. It is a collective name for the islands scattered mainly in the Pacific Ocean.

“WBBSE Class 8 Geography Chapter 11 notes, Oceania”

Of the numerous islands, Australia is the largest (7-68 million sq km) as it accounts for 87% of the landmass of Oceania, it was considered as a continent. Though a part of Oceania, Australia is the sixth largest country in the world, is itself regarded as an Island Continent.

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Location of Oceania: The continent of Oceania is located to southeast Asia. It extends from 114° east longitude in the west to 135° west longitude in the east and from 28° north latitude in the north to 47° south latitude in the south.

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Boundaries Of Oceania:

Oceania is bounded on the north by the Pacific Ocean (The northern boundary of Hawaiian Island) and on the south 47°S (Stewart Island) by the Antarctic Ocean. On the east by (135° W) the Pacific Ocean and on the west by (114° E) the Indian Ocean.

Area: Oceania comprises about 8-8 million square kilometers area. It is the smallest continent of the world.

Population: The total population of Oceania is about 3,5162670 (2011).

Regional Divisions: Oceania is the continent of a group of islands. The Islands of Oceania can be grouped into four major divisions-

1. Australasia,
2. Melanesia,
3. Micronesia and
4. Polynesia.

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“WBBSE Class 8 Geography Chapter 11, Oceania study guide”

Australasia: A group of the islands of Australia, New Zealand, and Tasmania is called ‘Australasia’. (‘Austral’ means ‘southern’). Australasia means ‘land of the south’. This region is situated in the Southern hemisphere. So, it is called Australasia.

Melanesia: ‘Melanesia’ means ‘Black Lands’. Islands, namely Papua-New Guinea, Soloman, and Fiji located to the northeast of Australia between the Equator and Tropic of Capricorn are groups as Melanesia. Due to the black skin colour of the inhabitants of that region, the name of that region is Melanesia.

“WBBSE Class 8 Oceania notes, Geography Chapter 11”

Micronesia: Micronesia, meaning ‘very small islands’, (Micro means small) lies to the northeast of Melanesia and is dominated by the island groups of the Marshalls, Gilberts, Carolines, and Marinas. These islands are located between the Equator and the Tropic of Cancer.

Polynesia: The meaning of Polynesia is ‘many islands’ (‘Poly’ means ‘many’). These islands located to the east of the International Date Line are grouped as Polynesia. It includes Hawai, Samon, Tonga etc.

Geographical Importance of Oceania: In spite of many obstacles to development like vast desert tracts and barren uplands, absence of natural harbors, and difficulties in constructing roads and railways. Oceania developed mainly due to its geographical importance.

1. The location of Oceania is of international importance as Asia is located to the east and America to the west of it.
2. The uniqueness of the continent lies in its geographical isolation from the rest of the world. The natural isolation of Australia has resulted in the evolution of peculiar flora and fauna that are not found anywhere else in the world. Eucalyptus, Emu, Kiwi, Kangaroo, Koala bear, Platypus etc. belong to this continent only.
3. Seaports and airports help as halting centres for long-distance journeys.
4. The military base of many countries is also located here.
5. Australia, though many dry and locking in river water, has vast reserves of underground water in the form of Artesian basins. This has made farming possible even in areas of scanty rainfall.
6. Australia is the chief sheep-producing country in the world and also has large cattle farms. Good quality sheep like Merino and cattle like Jersy built up a prosperous economy. It is now the world’s leading exporter of wool, frozen mutton, and beef.
7. The continent is well endowed with minerals like gold, silver, iron ore, bauxite, lead, zinc, petroleum, and coal.
8. All the developed countries have to depend on the dairy and animal products of this continent.
9. The development of railways, Commonwealth roads, and domestic aviation (air transport) have had a great effect on the high development of this continent.
10. Islands of the Pacific Ocean attract many tourists from other continents.
11. Oceania is a sparsely populated continent. Due to less population pressure farmlands are now plenty and vast resources of minerals are yet to be tapped. So, rich in natural wealth, certainly, this continent will become the focus of international importance.
12. Due to prosperity and uniqueness the future of this continent, especially Australasia, looks bright.

Chapter 11 Oceania: Physical Features of Oceania

There are innumerable islands in Oceania, as such, the physiography of different island groups is discussed below.

Physiography of Australasia: Physiography of Australia: Physiographically Australia can be divided into four divisions:

1. Eastern Mountains,
2. Western Plateaus,
3. Central Plains and
4. Coastal Plains.

 

1. The Eastern Mountains: The Eastern Mountains/Highlands or the Great Dividing Range, forming the highest part of Australia and occupying the eastern part of Australia. It is 3250 km long with a height varying between 1000-1500 m.It extends from Cape York Peninsula in the north to Tasmania across the Bass Strait. It has different names, such as Darling Range in Queensland, New England Range, Liverpool Range, Blue Range in New South Wales, and Australian Alps in Victoria.Mt. Kosciusko (2231 m), the peak of the Great Dividing Range is the highest peak of Australia. Townsend, the second highest peak (2211 m) in the country is located at Victoria.
2. The Western Plateau: An extensive undulating plateau occupies the western part of Australia. This is the oldest part of Australia. It is made up of old crystalline rocks known as the ‘Australian Shield’.The ancient land has been eroded to form a vast low plateau between 450 and 500 meters in height. Only the most resistant rocks still rise above the flat surface as low residual ranges (900 to 1500 m) such as Hamersley Range, and Albert Edwin Range in the West.The eastern section of this plateau is called ‘Barkley Table land’. There are a few hills, such as Macdonell Range, Musgrave Range, etc. There are a few deserts in this plateau region, such as the Great Sandy Desert, Gibson Desert, and Victoria Desert.
3. The Central Plains/Lowlands: There is a lowland between the Great Dividing Range in the east and the plateau in the west. In the southern part of this plan, there are Flinders Range, and Grey Range mountain. The southern part of this plain is called

1. Murray-Darling River Basin, the Central part of this plain is called
2. Lake Eyre Basin and the northern part is called
3. Carpentaria plain.
4. The Coastal Plains: Coastal Plains of Australia are usually narrow except in the north, the Carpentaria coastal plain, and in the South, the Great Australian Bight coastal plain is wide.
   
   The Great Barrier Reef: The Great Barrier Reef (2000 km long), the world’s biggest and longest coral reef is located to the northeast of Australia. It stretches along the eastern coast from Cape York to Rockhampton. It is formed of dead coral polyps and other lime-secreting organisms.

Physiography of New Zealand: New Zealand comprises

1. North Island,
2. South Island,
3. Stewart,
4. Chatham and many other small islands and is located to the southeast of Australia.

A series of fold mountains form the backbone of New Zealand. It is a part of the ‘Pacific Ring of Fire’ where earthquakes and volcanic activities are common.

In the central part of North Island, there are small active volcanoes like Ruapehu and Tongariro. Hot springs and geysers are also common in parts of the island. Mt. Egmont (2400 m), an extinct volcano is the highest peak of North Island. Ruahine Range and Kuimanawa Range is also important.

“Class 8 WBBSE Geography Chapter 11, Oceania easy explanation”

The principal range of the South Island is called the Southern Alps. They contain glaciers and twenty peaks above 3000 metres. The highest peak of this range is Mt. Cook (3764 m). This is the highest peak of New Zealand also. To the east of this island is Canterbury plain.

Physiography of Papua-New Guinea: The Melanesian islands like New Guinea which was once joined to Australia and is called a continental island. New Guinea is mountainous in nature and folds mountain ranges called the Central Cordillera to extend across the island from west to east.

Between the parallel mountain ranges lie broad upland valleys. The average height of the mountain chain is 3000 metres. The highest peak of Oceania is Mt. Wilhelm (4509 m/4700 m) of Papua New Guinea.

Physiography of Micronesia and Polynesia: The island groups of Micronesia and Polynesia are oceanic islands and consist of low coral islands and high volcanic islands. Some volcanic islands still have active volcanoes.

Mouna Kea (4205 m) and Mouna Loa (4169 m) are two active volcanoes of Hawaii, Kilauea is also an important volcano Coral islands are Gilbert, Marshall etc.

Chapter 11 Oceania: Rivers of Oceania

Oceania, the ‘continent of islands’ consists of about ten thousand islands. Of the numerous islands, Australia is the largest followed by Papua New Guinea and New Zealand. So, the major rivers of Oceania are mainly found there.

Characteristics of the rivers of Oceania are as follows:

1. Though Australia is the largest landmass of Oceania, but there is a vast arid desert tract. Due to high temperatures, uncertain and less rainfall only a few number of rivers are found there.
2. Great Dividing Range is the principal watershed of Australia.
3. Most of the rivers of Australia as well as Oceania are short in length.
4. These rivers do not contain much water during the dry season. They exist only during the rainy season.
5. There are a few inland rivers.
6. The rivers partially dry up in summer and their courses are marked by pools of water in places.
7. The rivers of New Zealand are good for the generation of hydel power.
8. In the small islands of Oceania, rivers are short and not mentionable.

Major Rivers of Oceania:

Region/Country	Name of the Rivers	Source of the Rivers	The mouth of the Rivers	Specific Characteristic
Australia	Murray (2589 Km)	Australian Alps.	Encounter Bay	Murray-Darling is the Longest river (3718 km) in Oceania
	Darling (2739 km)	New England Range
New Zealand	Waikato (425 km)	Benmore Lake	Pacific Ocean	The longest river of New Zealand
	Clutha (320 km)	Wanaka Lake
Papua New Guinea	Fly(1045 km)	Victor Emanuel Range	Gulf of Papua	The largest and most important river of New Guinea

The rivers of Oceania may be described as follows:

Rivers of Australia: The rivers of Australia can be grouped into the following four categories.

1. The rivers drained into the Southern Ocean.
2. The rivers drained into the Pacific Ocean.
3. The rivers drained into the Indian Ocean.
4. Inland rivers.

1. The rivers drained into the Southern Ocean: The major rivers of this region are the Murray, the Murrumbidgee, the Darling, the Lachlan etc.The Murray (2589 km): The river Murray is the principal river of Australia. It rises in the Australian Alps in Victoria and flows westward. It forms the major part of the boundary between New South Wales and Victoria. Then it enters South Australia.Before entering Encounter Bay on the Great Australian Bight, the Murray passes through Alexandria-a shallow lake. Being Snow fed the river is navigable throughout the year. Mildura and Wentworth are two important towns on the Murray.The Murray with its tributaries-the Darling, Murrumbidgee, Lachlan, and the Goulburn-forms the largest river system of Australia. The combined flow of Murray-Darling is the longest river (3718 km) of Oceania.The Darling (2739 km): The Darling is the chief tributary of the Murray. It rises in the New England Range and flowing southwestward, meets the Murray at Wentworth. The Darling is fed by the Warrego and a few rivers flowing from the Eastern Highlands.On account of the very gradual slope, the Darling flows sluggishly across the hot and dry plain where evaporation is very rapid. So the river partially dries up in summer and its course is marked by pools of water in places.The Murrumbidgee (1579 km): The Murrumbidgee is another tributary to Murray. It rises in the Snowy Mountains and joins the Murray. The Lachlan is its main tributary.The Lachlan (1550 km): The Lachlan is the main tributary of the river Murrumbidgee. It is a snow-fed river but the volume is small in dry seasons.
2. The rivers drained into the Pacific Ocean: Some other rivers of the continent of Oceania are the east flowing. Hawkesbury and Burdekin rivers rise from the Eastern Highlands and flow to meet the Pacific Ocean. Mitchel and Flinders flow towards N.W. and fall into the Gulf of Carpentaria.
3. The rivers drained into the Indian Ocean: The Murchison, Gascoyne, Fortescue, De Grey etc. are the rivers of Australia which are rise in the Northern part of the Western plateau flow westward and enter into the Indian Ocean. The Fitzroy, Victoria and Ashburton are also three important rivers flowing into the Indian Ocean.
4. Inland Rivers: There are a few inland rivers such as the Cooper, and Eyrein Australia.

The Cooper or Barcoo (1420 km): It is also called Cooper’s Creek is an intermittent stream. It rises from Warrego Range in Queensland and flows into Lake Eyre only during the rainy season.

The rivers of New Zealand: The longest river of Newzealand is Waikato (425 km). It rises from the Benmore Lake flows towards north and west and enters into the Pacific Ocean.

1. The river Wang a nui (290 km) rises in Tongariro Nation Park flows west and southward falls into the northern part of the Cook strait.
2. The river Clutha (320 km) rises in Wanka lake flows towards the southeast and enters into the Pacific Ocean.

Other important rivers of New Zealand are the Wainsakariri, Rangitata, and Rakaia which form the Canterbury Plains of the South Island and the Waikato and Rangitaiki of the North Island.

The rivers of Papua-New Guinea: The Fly (1045 km) is the largest and most important river of New Guinea. It rises in the mountains of Papua in the Victor Emanuel range and flows over the southwestern plain to enter the Gulf of Papua.

Lakes of Oceania: There are a number of big lakes in Oceania, such as

1. Eyre (10000 sq. km)
2. Gairdner,
3. Torrens and
4. More, in Australia,
5. The Anau and
6. Taupo (616 sq. km) in New Zealand.

Lake Eyre is the largest lake in Oceania. Lake Taupo is the largest volcanic lake on the North Island of New Zealand.

Artesian well: The presence of Artesian wells is the most important natural feature in Australia. Rainwater collected in the impermeable syncline rock comes up by normal water pressure. These are called Artesian wells which are scattered over extensive areas in Australia.

Chapter 11 Oceania: Climate Of Oceania

The climate of Oceania is very much diversified. Different parts of the continent have a great variety in the character of climates. The important characteristics of the climate of Oceania are as follows:

1. Generally, there is less rainfall occurs in the continent of Oceania, but there are some small islands where much rainfall occurs throughout the year.
2. The seasonal climatic characteristics are different in the northern and southern parts of this continent due to their location in the Southern and Northern hemispheres. When summer occurs in the Northern hemisphere, then winter occurs in the Southern hemisphere.
3. A vast tract of Australia is covered by deserts but most of the small islands of the Pacific Ocean have moderate and comfortable climate is found due to their size and nearness location to the ocean.
4. Different controls or factors of climate have played an important role to diversify the climate of Oceania.

The factors of climatic variations in Oceania are as follows:

Latitudinal extent: The continent of Oceania extends from 28°N latitude (the northern boundary of Hawaiian islands) in the north to 47°S latitude (Stewart island) in the south. Due to many differences of latitudes, different types of climate are seen in different parts of Oceania.

The equator passes through the northern parts of Oceania and the Tropic of Capricorn (23° 30°) passes through the middle of Australia, as such climate of the northern part of Oceania is equatorial (hot and humid) and the climate of Australia is warm in the north and is temperate in the south.

All of New Zealand lie in the temperate zone, its climate is also temperate. In the northern part warm temperate and in the southern part cool temperate.

Distance from sea/continental location: By virtue of its vast size and extent, the interior part of Australia belongs continental location as such middle and northern parts of Australia, extreme climatic conditions prevail. Due to the extremity of climate less rainfall and high temperature arid and semi-arid desert-type climate is found there.

Altitude: The effect of altitude on the climate of Oceania is experienced in lofty mountainous areas. Due to the increase of altitude temperature decrease and as such the peak regions of the mountains become snow-covered.

Ocean Currents: Some ocean currents, such as the cold Antarctic current, cold West- Australian current, warm Australian current etc. influenced the climate of the coastal areas of Oceania. However, droughts associated with the El Nino phenomenon have been frequent in recent decades in northern Australia and Papua New Guinea.

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Oceanic or Maritime Influence: Most of the island countries of the Pacific and small islands of Oceania are dominated by maritime influence. Due to this effect moderate climate and more rainfall humid climate is found in the small islands and the coastal areas of Oceania. New Zealand, being surrounded by the sea has a mild maritime climate.

Wind Persistent trade winds dominate much of Oceania, and Tropical. Cyclones often cause considerable damage.

Seasonal conditions of the important elements of climate in different parts of Oceania:

Temperature: There is differences in the temperature of the northern and southern part of Oceania. In the regions which are located in the southern hemisphere, seasons are reversed then the regions which are located in the northern hemisphere.

So in the southern hemisphere, January is a summer month while July is a winter month. In summer (December, January, February) nearly the whole of Australia has a temperature of over 27°C and in the interior, the temperature shoots up to well over 35°C.

January and February are the hottest months is Australia. The annual average temperature of New Zealand varies between 11°C and 19°C, snowfall occurs in winter (June, July, and August) in North Island. The temperature of Papua New Guinea is high as it is located near the Equator.

Air pressure and Wind: Moist north-west monsoon wind blows in summer over northern parts of Australia. But, in general, the south-east Trade wind blows in most parts of the continent.

Rainfall: In summer, the southeast Trade winds blow onshore nearly all along the whole east coast of the continent causing heavy rainfall, especially in northeast Australia. In winter, the south-east Trade winds in northern Australia blow towards south-east Asia., Being off-shore winds, they cause no rainfall.

East and North-west coast of Australia, the western part of Tasmania, the western part of New Zealand, and the entire Papua-New Guinea receive an average rainfall of 100 cm Interior and western parts of Australia receive only 25-50 cm. rainfall, as such, a number of deserts have formed there.

Climatic Regions of Oceania: Based on variations in temperature rainfall, air pressure, and wind, the continent of Oceania can be divided into the following climatic regions.

1. Tropical Monsoon Climatic region
2. Tropical Maritime Climatic region
3. Tropical Continental Climatic region
4. Equatorial Climatic region
5. Warm-Temperate Maritime Climatic region
6. Warm-Temperate Continental Climatic region
7. Mediterranean Climate Region
8. Hot Desert type of Climatic region
9. Cool Temperate or British type of Climatic region.

Climatic Region Of Oceania:

Climatic Type	Location	Characteristics
1. Tropical Monsoon Climate	This climate is seen in the eastern and northern parts of Australia.	1. Rainfall occurs during summer. 2. The winter is mild and dry. 3. Rainfall and climate is influenced by monsoon wind. 4. Amount of annual rainfall is about 100cm.
2. Tropical Maritime Climate	This climate is found in the northeastern part of Australia.	1. Hot summer. 2. Year-round rain, with summer maximum. 3. Annual rainfall is about 150 cm.
3. Tropical Continental Climate	This is a climate of northwestern and part of Central Australia.	1. Hot summer. 2. Cool winter. 3. Annual rainfall is 25 – 100 cm, occurring mainly in summer.  4. Semi-arid type of climate.
4. Equatorial Climate	Islands of Micronesia, Melanesia, and Polynesia experience equatorial climates.	1. Temperature is high (28°C). 2.  Annual rainfall is about 200 cm. 3.  Rainfall occurs throughout the year. 4. Hot and Humid climate.
5. Warm Temperate Maritime Climate	This climatic region is located in the southwestern part of Australia.	1. Hot summer. 2. Mild winter. 3.  Annual rainfall is 100 – 200 cm. 4. Rainfall occurs mainly in summer.
6.    Warm Temperate Continental Climate	This climatic region is situated in the southeastern part of Australia and the western part of the maritime climatic region.	1. Hot summer. 2. Mild winter. 3. Annual rainfall is less, about 60 cm. 4. Rainfall occurs in Summer.
7.    Mediterranean Climate.	Southern and South-western coasts of Australia and North Island in New Zealand	1. Hot dry summer. 2. Cool wet winter. 3. Moderate climate throughout the year. 4.  Amount of rainfall is 60-75 cm, and mainly occurs in winter.
8. Hot-desert type of Climate	This is the climate of western and Central Australia.	1. Rainfall is scanty. 2. This region is nearly dry. 3. Rainfall is less than 25 cm. 4. The summer is hot and the winter is cold.
9. Cool Temperate or British type of Climate.	This type of climate is found in southeast Australia, Tasmania, and New Zealand.	1. Moderately warm summer.  2. Quite a cold winter. 3. The westerlies cause heavy showers throughout the year. 4.  Amount of rainfall is 100 cm to 200 cm.

 

Chapter 11 Oceania Natural Vegetation of Oceania

Natural Vegetation of Oceania:

Natural vegetation is characterized mainly by the influence of climate. As the continent of Oceania has a variety of climates, so due to climatic variation different parts of Oceania have different types of vegetation. The natural vegetation of Oceania can be divided into the following types.

1. Tropical Evergreen Forest: Tropical Evergreen Forests are found along the northeastern coasts with hot and humid summer and mild winters where the annual rainfall is 150 cm. Due to high temperature and humidity, the dense evergreen forest grows. Mahogany, Palm, Ebony etc. trees grow here. In different islands of Micronesia, Melanesia, and Polynesia this type of vegetation grows.
2. Tropical Grassland: In the north-central part of Australia tropical grasses grow as there the temperature is high and rainfall is scanty. In Australia, this grassland is known as ‘Parkland Savana’. Eucalyptus and jarrah trees are scattered is this grassland.
3. Temperate Evergreen Forest: In the southern part of east coast of Australia, Tasmania, and in New Zealand temperature is low but rainfall is high as such trees are evergreen like ash and eucalyptus. Varieties (about 400 species) of Eucalyptus grow here. The common trees are oak, poplar, and elm.
4. Temperate Grassland (Downs): To the west of the Great Dividing ranges, an extensive grassland of small grasses is found. This grassland is known as ‘Downs’. Small grasses grow in the temperate weather and scanty rainfall areas of the Murray-Darling river valleys of Australia.
5. Desert Vegetation: In the true desert of western and central Australia, the vegetation consists of very hard thorny grass called ‘porcupine’ grass and ‘spiny’ grass or ‘spinifex’. Surrounding this, there is a broad ring of scrublands consisting of saltbush, mulga, and mallee.
   
   
6. Mediterranean Vegetation: This type of vegetation covers the southwestern corner of Australia (New South Wales and Victoria) and Tasmania. Evergreen trees like Jarrah, Karri, grow in the Mediterranean Climatic region of southwestern Australia.
7. Tropical Deciduous Forest: In the western and northwestern part of Australia dominance of monsoon winds give rise to deciduous forest. Cedar, Birch, Palm and bamboo grow here.
8. Mountainous Vegetation: Due to the altitudinal effects the climate of the eastern mountains of Australia and the lofty mountains of New Zealand is changed as well as the vegetation of this region is also changed. In the lower mountain region mulga and mallee, in the middle Eucalyptus and above more different types of Pine is available.

Characteristics of Natural vegetation of Oceania:

1. Australia’s as well as Oceania’s long isolation of around 50 million years from the other parts of the world and its increasing aridity, caused its natural vegetation to change, adapt and evolve unique characteristics in order to survive. So vegetation of this region is predominantly different from that found in other parts of the world.
2. Because of hot and dry conditions, most of the vegetation is xerophytic and plants can live for long periods without water.
3. Eucalyptus usually called ‘gum trees’, and acacias such as the Golden Wattle are the two characteristic forms of vegetation.
4. The most typical tree is the eucalyptus of which there are more than 450 varieties adapting to an amazing variety of environments.
5. Some soft varieties of eucalyptus yield paper pulp some. yield oil and some wet eucalyptus like Jarra and Karri of the southwest provide hard timber.
6. Following the rainfall pattern, the vegetation belts occur in concentric circles with the desert scrub in the interior and forests and woodlands on the interior and forests and woodlands on the outer margins. In between these two lie the grassland.
7. The trees vary from very tall (100 metres) types to dwarf branching trees called ‘melee’ which grow taller than 2-3 meters.
8. Coniferous trees grow over the mountainous region and cocoanut and mangrove vegetation grow in the coastal areas.

Chapter 11 Oceania: Murray Darling Basin

Murray-Darling basin is the most economically prosperous area of Australia as well as the continent of Oceania. The almost flat land of the south-eastern part of Australia which is drained by the rivers of Murray-Darling and their tributaries is known as the ‘Murray-Darling Basin’.

This is the richest, most densely populated, and most developed area of Australia. This region is also famous for cattle rearing and agriculture.

Location: The latitudinal and longitudinal extent of this region are as follows. Latitudinally it extends from 25° south latitude on the north to 39°S latitude on the south. Longitudinally this region extends from 138°E longitude on the west to 150°E longitude on the east.

Boundary: This region is bordered on the north-east and south-east by the Great Dividing Range, on the west by Gray Range and Barrier Range; on the south-west by the Gulf of St. Vincent, Gulf of Encounter, and the Great Australian Bight. The bain covers a sizeable portion of New South Wales and small sections of Sn. Queensland, Victoria, and South Australia.

“WBBSE Class 8 Geography Chapter 11, Oceania important questions”

Area: Covering about 20% of the total area of Australia, the Murray-Darling Basin occupies about 1-14 million square kilometers of area.

Physiography: The Murray-Darling basin is almost a low depositional plain land. For a long period, Murray-Darling deposited sediments forming this plain land. The average elevation of the basin varies from 100-200 meters.

Being bounded by highlands on all sides of 35°S excepting the southwest the central plain rises gradually towards the west-east and northeast. However, the slope, in general, is from northeast to southwest.

River/Drainage: Murray-Darling is the principal river of this basin. The Murray (2589 km) originates from the Australian Alps and its main tributary Darling (1163 km) originates from the New England Range. These are snow-fed rivers, as such they are perennial.

The Confluence of the two rivers is near Wentworth city. Thereafter their joint channel flows southwest and drains out at Encounter Bay. Murrumbidgee is another important tributary to Murray. Lachlan is a tributary to Murrumbidgee. Pars, Warrego, Barron, etc. are tributary to Darling.

Climate: The climate of the Murray-Darling basin is generally temperate. The climate of the southern part (coastal areas) of the basin is Mediterranean type i.e. wet winter and dry summer. But it is an extreme type in the central and northern parts of the basin.

Rainfall is scanty in the central part of the basin. The average temperature during summer is 25°C and that in the winter months is 20°C. To the west of the Great Dividing Range, rainfall is less (50 to 75 cm).

“Class 8 Geography Oceania notes, WBBSE syllabus”

Soil: Soil of this region is mixed alluvial and chernozem type. This type of soil is suitable for agriculture because it is fertile.

Natural Vegetation: Due to scanty rainfall, the central part of the basin is occupied by grasslands called ‘Downs’. Evergreen trees like Eucalyptus, Jarrah, Karri, and blue-gum grow in the southern part of the basin when rainfall is. high.

In the semi-arid west grow the Mulga/Serub while the Mallee scrub consisting chiefly of dwarf eucalyptus grows in the Mediterranean. regions. In a few places, oak, poplar, birch, etc. deciduous trees are seen.

“WBBSE Class 8 Geography Chapter 11, Oceania summary”

Irrigation: The Murray-Darling basin is the most agriculturally prosperous area in Australia and needs only irrigation to yield rich crops. Dams such as the Hume on the Murray and the Burrinjuck on the upper Murrumbidgee are important for irrigation and hydel power.

The Snowy river has been dammed and its water is delivered by a tunnel through the mountains to increase the water supply in the basin. Artesian wells are also used to a great extent to tap underground water for irrigation purposes in the basin.

Agriculture: Murray-Darling Basin is agriculturally rich. This is a region of Intensive Farming. It is a type of farming where cultivable land is limited. Due to extensive plainland, fertile soil, temperate climate sufficient supply of water, capital, and use of modern technology Murray-Darling Basin is agriculturally developed.

“WBBSE Class 8 Chapter 11 Geography, Oceania solutions”

This region is one of the important wheat-producing areas of the world. The wheat farms extend across the basin from Adelaide to New South Wales. Important crops are wheat, barley, oat, tobacco, etc. Large quantities of wheat are exported to other countries.

Fruits, particularly grapes, oranges, lemons, apples, pears, apricots, and peaches are grown mainly for export. Grapes are mainly dried to make raisins and currants.

Sheep and Cattle Rearing: The Murray-Darling Basin is the biggest sheep-rearing area of Australia which is the world’s largest producer of wool. Extensive Downs grassland, temperate climate, less population, and modern technology help to develop Live-stock farming.

Merino sheep, once imported from Spain, yield the best wool. Lincoln, marsh, etc. are also reared in the Downs of Murray Darling Basin. Sheep stations of this area are large and a sheep farm or Squatter is helped by laborers called Jackaroos’.

Cattle are reared in the eastern grasslands for beef and as well as dairy products. This region is also famous for dairy products.

Mineral Resources: Minerals are produced from the marginal regions of the Murray- Darling Basin, such as silver, lead, zinc, copper, gold, and tin. Broken Hill is famous for its silver deposits. So ‘Broken Hill’ is popularly called ‘Silver City’.

Copper is the most important mineral of the basin and is mined at Cobber in New South Wales, Broken Hill also has deposits of lead and zinc. Bendigo of Victoria is famous for its gold mine.

Industries: Murray-Darling Basin is not developed in industries. Industrial development is limited only to

1. Food processing,
2. Engineering,
3. Chemical,
4. Dairy and
5. Meat processing etc.

Due to the lack of mineral deposits metallurgical industries have not flourished here. Depending on animal and agricultural resources wool, textile, flour, and bakery industries are also developed.

Important industrial centres are-Adelaide, Broken Hill, Mildura, Port Pirie, Morgan, Renmark and Albury.

“WBBSE Geography Class 8 Oceania, Chapter 11 key concepts”

Population and cities: The region is one of the most prosperous regions of Australia. So, settlement is uniform and the population by Australian standards, is fairly dense-about 4-6 persons/ sq. km. The population is concentrated in the coastal area.

Adelaide, the capital of South Australia and an important port and industrial center located near the Gulf of St. Vincent is the largest city and only a million cities in this basin. Other important cities of this basin are Broken Hill, Mildura Wentworth, etc.

WBBSE Notes For 8 Class Middle School Geography

Chapter 5 Cloud And Rain

What is Cloud:

Cloud Meaning 

Clouds, which are condensed water vapour, are one of the most visible marks (elements) of the weather. They form in distinctive patterns and often give a quick clue as to what weather might happen in the near future.

Meteorologically clouds are very significant because all forms of precipitation occur from them. It may be mentioned that not all clouds yield precipitation but no precipitation is possible without clouds.

Read and Learn all WBBSE Notes For 8 Class Middle School Geography

Chapter 5 Cloud And Rain: The Cloud Family

Clouds can be classified in two ways—
(1)According to height and
(2)According to shape and formation.

“WBBSE Class 8 Geography Chapter 5 notes, Cloud and Rain”

(1) Classification according to height: By height, clouds can be divided into three types:
1. High clouds
2. Medium clouds
3. Low clouds

(2) Classification according to shape and formation:

Clouds can be classified into four main types which are given Latin names. They are

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1. Cirrus—Looks like a feather or fine scales,
2. Stratus—they have a layered structure
3. Cumulus—they look like a mound of fully cotton and
4. Nimbus—they are rain clouds, giving plenty of rainfall.

 

 

High clouds: The lower limit of this cloud is 6000 to 12000 metres or above 20000 feet. There are mainly three types of clouds in the High cloud family. These are as follows:

1. Circus: 3 The high altitude detached clouds having feather-like or fibrous appearance are called ‘cirrus clouds’ They are composed of tiny ice crystals and are transparent and white in colour but have brilliant colour at sunset and sunrise. When the weather is clear these clouds are seen and-no rain occurs. So this cloud generally indicates fair weather.

 

2. Cirrocumulus: Cirrocumulus clouds are white-coloured clouds having cirri form layers or wave-like forms. They generally appear as the scaled body of a mackerel fish. So, the cirrocumulus cloud ‘Mackerel Sky’.This cloud usually indicates fair weather because from these clouds rain occurs.

3. Cirrostratus: Cirrostratus clouds are generally white in colour and spread in the sky like milky thin sheets. The sun and moon seen through this cloud have a halo. This cloud forms a rainbow. It signals storms.

“Class 8 WBBSE Geography Chapter 5 notes, Cloud and Rain study material”

Medium clouds: The lower limit of this cloud in between 2100 mts to 6000 metres (6500 to 20000 feet). There are mainly two types of clouds in the Medium Cloud falily. These are:
(1)Alto-cumulus and
(2)Alto-stratus

(1) Alto-cumulus: Alto-cumulus clouds are characterized by wavy layers of globular form. Sometimes these clouds are called as ‘sheep clouds’ or ‘wool- pack clouds because they are looking like scattered mounds of wool.

“WBBSE Class 8 Geography Chapter 5, Cloud and Rain study guide”

They appear white or grey in colour. In between the clouds blue sky is seen These clouds generally herald clear weather but when they accumulate in large amounts rain may occur.

(2) Alto-stratus: Alto-stratus clouds are thin sheets of grey or blue colour having fibrous or uniform appearance. The sun looks very hazy through this cloud. Rain occurs for a long duration and over large areas from this cloud.

Low clouds: The lower limit of this cloud is less than 2100 m. or 6500 feet. Most clouds are stratus or layered. There are mainly three types of clouds in the Low clouds family. These are
(1) Strato cumulus,
(2) Stratusand
(3) Nimbostratus.

“WBBSE Class 8 Cloud and Rain notes, Geography Chapter 5”

(1) Strato-cumulus: Strato-cumulus clouds are found in rounded patches between the height of 2500 m to 3000 m. They are of grey or whitish clour. They are composed of globular masses or rolls which are generally arranged in lines, waves or groups. So, they are also called ‘Bumpy clouds’.

They are generally associated with fair or clear weather but occasional rain on snow is not ruled out. During winter in temperate regions, often the sky is covered by this cloud giving heavy rainfall.

Humidity And Clouds

(2) Stratus: Stratus clouds are dense, low-lying fog-like clouds of dark grey colour but are seldom close to the ground surface. They are composed of several uniform layers and cover the entire sky. It does not extend high from the surface so creates invisibility at low levels. It is a great problem for mountaineers and air pilots. Often this cloud occurs drizzle.’

(3) Nimbostratus: Nimbostratus clouds are low clouds of dark grey to black colour, very close to the ground surface. They are so compact and thick (hundreds of metres) that there is complete darkness and there is copious precipitation.

“Class 8 WBBSE Geography Chapter 5, Cloud and Rain easy explanation”

‘Nimbo’ is derived from the Latin word ‘nimbo’ meaning thereby ‘rainstorm’, it indicates bad weather because it causes heavy rainfall. During cyclones it covers the whole sky and gives rainfall.

Vertical clouds or Clouds of great vertical extent: The height of the clouds extend from 1500 m to 9000 m, resembling a tree from below to above. There are mainly two types of vertical clouds. These are—

(1)Cumulus and
(2)Cumulonimbus.

“WBBSE Class 8 Geography Chapter 5 notes, Cloud and Rain PDF”

(1) Cumulus: Cumulus clouds are very dense, widespread, dome-shaped and have flat bases. They start from low levels but reach high above. The bottom of the cloud is flat but its top resembles a cauliflower.

The lower part of the cloud is dark grey or black but the higher part is white and the sun looks bright through it. It usually indicates clear and fair weather.

(2) Cumulonimbus: Cumulonimbus clouds are thunderstorm clouds. It is a huge dense cloud. The bottom and middle of the cloud is black in colour, the sides are white or grey.

It has a great vertical extent of about 4000 m upward from the layer of air adjacent to the earth’s surface. During ‘Kalbaisakhi’ these clouds are seen in the North-west corner of the sky.

“WBBSE Class 8 Geography Chapter 5, Cloud and Rain important questions”

These clouds cause heavy rain, storms or hailstorms accompanied by lightning, thunder and gusty winds. So it-is also called ‘Thunder Cloud’.

The origin of clouds: Cloud is the most common form of ‘Condensation’. When moist air rises, it cools down. The water vapour present in the air also cools and changed into minute droplets of water or crystals.

These droplets of water or ice crystals stick to dust and salt particles, floating in the atmosphere. These small water droplets or ice crystals form a floating mass called cloud.

“Class 8 Geography Cloud and Rain notes, WBBSE syllabus”

Thus, a cloud is nothing but a collection of countless droplets of water or the tiniest crystals of ice suspended in the atmosphere. These droplets or crystals are so small that they are blown about and carried with the slightest movement of air.

Evaporation: The process where by a liquid (water) changes into a gas (water vapour) is called evaporation. The water of the water bodies is changed into water vapour by solar energy. It mixes with other gases of the atmosphere. At 10°C. temperature, on cubic metre air can hold 11-4 gm water vapour. Warm air can absorb more water vapour than cold air.

Saturated air: When a specific quantity of airmass, at a particular temperature holds the maximum amount of water vapour as it can possibly hold is called ‘saturated air’. The amount of water vapour required to saturate the air depends on temperature and pressure.

Dew point: The temperature of air at which it becomes saturated with water vapour starts to condense to form water droplets is called ‘dew point’. The upper level of saturation is known as dew point.

“WBBSE Class 8 Chapter 5 Geography, Cloud and Rain solutions”

Condensation: The physical process of transformation from the vapour to the liquid state is called ‘condensation’. In the atmosphere, condensation occurs either when the temperature drops sufficiently for moisture to be cooled to its dew point, or when there is enough water vapour within an airmass for it to reach saturation point.

Distinguish between Evaporation and Condensation:

Evaporation	Condensation
1. Evaporation is a process by which water changes into a vapour.	1. Condensation is a process by which water vapour present in the air changes into minute droplets of water.
2. It takes place more when the weather is hot, dry and windy.	2.  It takes place when the temperature of the saturated air goes down below the dew point.
3. It also takes place more quickly in the lower latitudes.	3.  It also takes place more quickly at higher latitudes than at lower latitudes.
4. As a result of evaporation the amount of water on the surface of the earth goes on decreasing and decreasing	4. As a result of our censer or the amount of water goes on increasing arc increasing.

 

Some forms of condensation:
(1) Fog: Droplets of water suspended in the lower layers of the atmosphere resulting from the condensation of water vapour around nuclei of floating dust or smoke particles is called ‘fog’. Its visibility is less than 1 km.

(2) Mist: A reduction of visibility within the lower atmosphere to 1—2 km caused by condensation producing v/ater droplets within the lower layers of the atmosphere is called ‘mist’. It is intermediate between fog and haze.

“WBBSE Geography Class 8 Cloud and Rain, Chapter 5 key concepts”

(3) Haze: An obscurity of the lower atmosphere that limits visibility to under 2 km, but over 1 km, is called ‘haze’. It is normally formed by water particles that have condensed around nuclei to the atmosphere but may also be a result of particles of smoke, dust or salt in the air.

 

 

(4) Smog: A form of fog that occurs in areas where the air contains a large amount of smoke is called ‘smog’ (Smoke + fog).

Humidity: Humidity means the amount of water vapour present in the air. Water vapour is always present in the air. About 2% of the atmosphere consists of water vapour. Most of the water vapour of the atmosphere comes from the oceans, lakes, and rivers through evaporation.

(1) Absolute Humidity: Total amount of water vapour present in air at a particular temperature is absolute humidity. It is defined as the weight of water vapour per unit volume of air. It is expressed as grams per cubic metre of air.

Distribution:
1)Absolute humidity is maximum in the equatorial region,
2)It is more in summer than in winter, similarly, it is higher during the day than at night.

(2) Relative Humidity: Relative humidity is expressed as a percentage. It is the ratio between the actual amount of the water vapour present in the air at a temperature and the maximum amount of water vapour that the same volume of air can hold at a given temperature.

⇒ \(\text { R.H. }=\frac{\text { Actual amount of water vapour present in air }}{\begin{array}{l}
\text { The maximum amount of water.vapour present in the } \\
\text { same air can hold at given temperature. }
\end{array}} \times 100\)

In other words, it is a ratio, expressed in percentage, between the absolute humidity and the maximum vapour capacity of the air.

“WBBSE Class 8 Geography Chapter 5, Cloud and Rain summary”

⇒ \(\text { R.H. }=\frac{\text { Absolute humidity }}{\text { Vapour capacity }} \times 100\)

Example: An air at 20°C temperature has 8 grams of water vapour per cubic metre actually present. But the air at 20°C temperature can hold 16 (gms) of water vapour as per cubic metre.

∴ \({ R.H. }=\frac{8}{16} \times 100=50 \%\)

When the relative humidity is 100%, the air is fully saturated.

Distribution:
1) Relative humidity is maximum at the Equator and decreases polewards,
2) It is low in hot deserts, in continental interiors, as in areas of anti-cyclonic conditions.

3)Specific Humidity: The humidity of the atmosphere expressed as the ratio of the weight of water vapour (in grams) to the total weight (in kilograms) of a given volume of air is called Specific humidity. This varies from about 0-2 gm/Kg in very dry cold arctic air to over 18-0 gm/Kg in hot humid tropical air.

Distinguish between Relative humidity and Absolute Humidity:

Relative Humidity	Absolute Humidity
1. It is a ratio between the actual amount of water vapour present In the air at a particular temperature and the maximum amount of water vapour that the air can hold at that temperature.	1. The total amount of water vapour present in the air at a particular temperature is absolute humidity.
2. It is a ratio between the absolute humidity and vapour capacity of the air.	2. It is defined as the weight of water vapour per unit volume of water.
3. It is maximum In the equatorial region, but is lowest in hot deserts.	3. It Is maximum over oceans and lowest in high-pressure areas.
4. It is expressed as a percentage.	4.  It is expressed as grams per cubic metre of air.

 

The Importance of Relative Humidity: Relative humidity is daily life. Some important points have been mentioned here.

(1) It is possible to find out the possibility of rainfall with the help of relative humidity.
(2) Relative humidity is essential to agricultural operations.
(3) Many chemicals and medicines deteriorate in high relative humidity.
(4) It is necessary to take into account the relative humidity before constructing buildings.
(5) Radio, Television, electric instruments and other scientific instruments are affected by relative humidity.
(6) High relative humidity do not enjoy good health. Even very low relative humidity is not conducive to health. It has been found that a relative humidity of 60% is most suitable for human health.

The Proportion Of Relative Humidity Changes According To Altitude

The Measurement of Relative Humidity: Relative humidity is measured with the help of various types of Hygrometers. The most common Hygrometer is known as ‘Dry and West Bulb Thermometer’.

Precipitation: The particles of water or ice that form within clouds and fall towards the earth surface is Precipitation. According to famous climatologist H. J. Critehfield, “Precipitation is defined as water in liquid or solid forms falling to the earth.” Precipitation includes all forms in which moisture falls on the earth’s surface.

It is the process by which condensed water from clouds falls on the earth’s surface. It can be solid or liquid. Precipitation is a complex process when millions of drops of water combine together and fall on the earth.

“WBBSE Class 8 Geography Chapter 5 Cloud and Rain, definitions and examples”

Forms of Precipitation: Different forms of precipitation are:
1. Rainfall,
2. Snowfall,
3. Hail,
4. Dew,
5. Frost,
6. Sleet,
7. Drizzle,
8. Glaze.

1. Rainfall: The release of moisture in the form of drops of water is called ‘rainfall’.After condensation of moist laden air, clouds are formed. Teh drops of water become so heavy that air cannot hold these. The falling of these drops of water from the clouds is called ‘rainfall’.

2. Snowfall: A from of precipitation consisting of crystals of ice is called ‘snow’.it is produced when condensation takes place at a temperature below freezing point, (0°C), so that the minute crystals of ice form directly from the water vapour.

These small crystals then unite to form flakes of ice called snow.The coming down of snow flakes towards the earth’s surface is known as ‘snowfall’.It is common in higher latitudes and high mountain regions.

 

3. Hall: Precipitation in the form of pellets of ice (hailstone) that develop in and fall from a cumulonimbus cloud, either at a cold front or where intense heating of the surface causes rapidly ascending convection currents is called hail.

“WBBSE Class 8 Geography Cloud and Rain, revision notes”

When they become so big and heavy that the air can no longer hold them. Therefore, they fall back to the earth’s surface as hailstones. Hailstones cause damage to crops and buildings.

 

4. Dew: When the temperature for the air is higher than the dew point and a cool object having a lower temperature comes in contact with such air. This causes condensation in the air The drops of water thus formed rest on the cold object like grass, leaves, rocks, etc.

These drops of water on the cold objects are called dew. The conditions favouring dew formations are moist air, light winds, and clear night skies to ensure maximum cooling by radiation.

 

5. Frost: A weather condition that occurs when the air temperature is at or below the freezing point (0°C), the water vapour will condense to form an icy deposit. It is called frost.

6. Sleet: In the U. K., Sleet is described as a form of precipitation consisting of either partly melted snow-flakes or rain and snow falling together. In the.U.S.A., Sleet is described as a form of precipitation consisting of frozen raindrops that have subsequently partially remelted. So Sleet is considered as a mixture of rain and snow.

7. Drizzle: Light rainfall, consisting of particles of size less than 0-5 mm in diameter and are close together is called ‘drizzle’. Normally drizzle is produced by stratus and strato- cumulus clouds.

8. Glaze: A covering of smooth clear ice that coats objects and surfaces is called ‘glaze’. It occurs when supercooled water droplets freeze on contact with a surface and when a fall in temperature causes wet surface to freeze.

Distinguish between Precipitation and Rainfall:

Precipitation	Rainfall
(1) The particles of water or ice that form within clouds and fall towards the earth is precipitation.	(1)The release of moisture in the form of drops of water is called rainfall.
(2) It is the collective name given to different forms of moisture after condensation.	(2)It is a type of precipitation when moisture falls on the earth in the form of droplets of water.
(3) Precipitation has two forms—liquid and solid.	(3)Rainfall has only liquid form.
(4) Rainfall, snow, hail, drizzle, sleet, dew, frost and glaze are the common forms of precipitation.	(4) Three major types of rainfall are—(1)Convectional,(2)Relief or Orographic and (3)Frontal or cyclonic rainfall.

 

How is Rainfall caused: Humidity is the basis of rain. The general cause of rainfall is the cooling of saturated air. The mechanism of rainfall passes through a number of stages:
(1)Air should have plenty of water vapour,
(2)That air should be saturated with moisture,
(3)The air should get cooled or get the chance to come in contact with the cold air for condensation and
(4)Condensation of water vapour makes droplets. Thus the release of moisture in the form of drops of water is called ‘rainfall’.

Types of Rainfall: On the basis of mode of formation and process of cooling of air, there are three types of rain.
(1) When the air is cooled by rising convection currents (Convectional rainfall).
(2) When moist air is cooled due to ascent along a mountain barrier (Orographic or Relief rain).
(3) When air is cooled due to the meeting of warm and cold air masses.(Frontal or Cyclonic rain).

(1) Convectional Rainfall: Convectional rainfall is formed when the air is cooled by the rise of the convectional current. It happens when the land is intensely heated, the hot and moist air rises up vertically as convection currents.

As it rises up, it expands and cools due to the release of pressure. Hence, condensation takes place resulting in a cumulus or cumulonimbus clouds.

Consequently, it results in torrential rainfall. The equatorial region of low latitude experiences convectional rainfall. In this region, the convectional system is best developed because daily heating of the ground surface up to noon causes convection currents.

Consequently, the sky becomes overcast by 2—3 p.m. daily causing pitch darkness and heavy rains and the sky becomes clear by 4 p.m. So it is called 4 O’ clock rain. Thus, the convectional rainfall in the equatorial region is a daily regular feature.

 

Characteristic features of convectional rainfall:
(1) It occurs daily in the afternoon in the equatorial region.
(2) It is of very short duration but occurs in the form to heavy showers.
(3) It occurs through thick dark and extensive cumulonimbus clouds.
(4) It is accompanied by cloud thunder and lighting.

(2) Orographic or Relief Rainfall: Orographic rainfall occurs when moist air is cooled due to ascending along a mountain slope or a plateau barrier. The moist wind coming from the sea rises up along the slope of the land and comes in contact with cool upper atmosphere.

As a result the moist air condenses and rainfall occurs. Since this type of rainfall is caused by the relief of the land, it Is known as relief rainfall’. The the windward slopes’ gets maximum rainfall.

 

Distinguish between “Leward slope’ and ‘Windward slope”:

Windward Slope	Leward Slope
(1) Windward side is the side of the mountain which faces the moisture (rain-bearing winds).	(1) The Leward slope/side is the side of the mountain which is opposite the windward side.
(2) On the windward side, the air ascends and becomes cool.	(2) On the Leeward side the air descends and gets warm.
(3) When the moisture-bearing winds climb the windward side of the mountain, they cool down and bring heavy rainfall.	(3) When these air cross over to the other side (Leward side) they have already lost much of their moisture. While descending they further become warm and dry so they give less rainfall on the Leeward side.
(4) The western slope of the Western Ghats gets more rain because they form the windward side.	(4) The Eastern slopes of the Western Ghats get lesser rain because they form the Leeward side.

Chapter 5 Cloud And Rain: Characteristic Features Of Orographic Rainfall

 

• The windward slope, also called as rain slope, receives the maximum amount of rainfall whereas the leeward side of the mountain gets vey low rainfall. .
• There is maximum rainfall near the mountain slopes and it decreases away from the foothills.
• Orographic rainfall may occurs in any season’ Unlike other types of rainfall it is more widespread and of long duration.
• The amount of rainfall increases with increasing height along the windward slopes of the mountains.

Distinguish between Convectional Rainfall and Orographic Rainfall:

Convectional Rainfall	Relief/Orographic Rainfall
1. This rainfall is caused by convection currents.	1. This rainfall is caused when a mountain forces the winds to rise.
2. The rising air expands and is cooled to give rainfall.	2. It occurs in mountainous regions.
3. It gives heavy showers for a short period.	3. It gives heavy rainfall on a windward slope, but Leeward slope is dry and is called Rainshadow
4. The equatorial region gets heavy showers in the afternoon daily.	4. South-West Monsoons give heavy rainfall on the Western Ghats, but the Deccan plateau lies in rain-shadow.

 

(3) Cyclonic or Frontal Rain: When hot and air masses move towards each other, parallel to the earth’s surface along a front, the cold air being heavy flows near the earth’s surface, while the hot air blows above it, rises and expands to cool and condense to form rainfall.

This is called “Cyclonic Rain’ because as this rain is associated with cyclones. This rain is common in North-West Europe in winter, Punjab plains experience rainfall in winter from cyclones coming from the Mediterranean Sea.

Chapter 5 Cloud And Rain: Characteristics of Cyclonic Frontal Rain

1. This rainfall is slow, continuous and extensive.
   The mechanism of cyclonic rainfall is of two types:
   1)Temperate cyclone and 2) Tropical cyclone.
2. This rainfall associated with a warm front is widespread and long-duration.
3. Sometimes this rainfall- occurs in the form of snowfall and hailstorms.
4. Most of the rains of temperate regions are received through cyclones.
5. If tropical cyclones are full of moisture become saturated and yield heavy showers characterized by lightning and thunder.

Raingauge: The amount of rainfall is measured by an instrument called ‘Raingauge’.

Importance of Precipitation: Precipitation is an important factor of weather and climate. Rainfall often brings a cooling effect on the weather. During intense summer rainfall offers a great relief of the people.

“Class 8 WBBSE Geography Chapter 5 Cloud and Rain, multiple-choice questions”

Temperature goes down due to heavy showers. Snowfall often brings very chilled weather and people suffer from shivering cold.

WBBSE Notes For 8 Class Middle School Geography

Chapter 9 North America

Introduction Of North America :

North America is the third largest continent of the world, after Asia and Africa. A few centuries ago, this continent was almost unknown. But now it has made great materialistic progress and it is the principal centre of modern civilization and has achieved world supremacy in almost every sphere, such as economy, education, science and technology, politics, and industrial development.

“WBBSE Class 8 Geography Chapter 9 notes, North America”

Discovery/Expedition of North America:

About 5 centuries ago the Europeans had the hobby to discover the unknown or new lands of the world and they started expeditions in different parts of the world. The great Italian Navigator, Christopher Columbus discovered the Eastern Islands of North America (Islands of West Indies) in the year 1492 A.D.

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He sailed westward from Spain, believing that the earth being round, he would reach India by sailing towards the west. Nobody knew that there was a big continent of North America in the mid-ocean.

Columbus, in fact, landed on the islands now named as ‘West Indies’ It was he who termed the red-skinned people of these islands as ‘Indians’ thinking that he had reached India. In 1497 A.D., another Italian, Amerigo VespuccActually touched the mainland of North America. The continent derives its name from him.

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“Class 8 WBBSE Geography Chapter 9 notes, North America study material”

North America became separated from South America by constructing the Panama canal and navigation become easy between the Eastern coast of North America and Europe and the Western coast of South America Panama Isthmus narrow strip of landmass (a width of just eighty km) lying between North America and South America and joins two continents is called Panama Isthmus or Isthmus of Panama.

Class 8 Geography Chapter 9

Since 1914 A canal has been dug through the Isthmus of Panama, connecting the Atlantic and the Pacific Oceans is called the ‘Panama Canal’. Why North America is called the ‘New world’ The continent was unknown to the Europeans and others for a long period.

Therefore, when the continent of North America was discovered by the Europeans, they called it as ‘New World’.

Location of North America:

North America lies entirely within the Northern and Western hemispheres. It stretches from 7°12′ North (south of Panama) to 83°07′ North latitudes (North of Greenland) and from 52°37’W to 172°27′ West longitudes. It extends for 8480 km from North to South and for 6400 km from West to East. 100°W meridian bisecting the continent longitudinally.

Boundaries of North America:

North America Is bounded on the north by the Arctic Ocean, on the south by the Panama Canal and the Pacific Ocean, and where it is linked with South America by a narrow land bridge—the Isthmus of Panama. On the east it is bounded by the Atlantic Ocean, and on the west by the Pacific ocean.

To the northwest, the continent is separated from Asia by the Beiring strait which is only 58 km wide and to the south, the continent is separated from South America by the Panama canal. North America includes a few islands, such as-

1. Greenland (the largest island of the world) in the north,
2. New Foundland in the east,
3. Cuba and Jamaica in the east and
4. Hawaiian islands in the west.

“WBBSE Class 8 Geography Chapter 9, North America study guide”

Area: North America covers an area of 2,44,00000 square kilometers and ranks third in size (next to Asia and Africa) amongst the continents of the world.

Population: The population of this continent is about 465,000,000.

Geographical Importance of North America: North America is the most dynamic and powerful continent in the world. This significant importance of the continent has been achieved mainly due to several geographical factors.

These are as follows:

1. Favorable Location: Though this continent is not centrally located like, Europe, North America is placed favourably for trade with Europe across the Atlantic and with Japan and South-East Asia across the Pacific. The Panama canal across the isthmus of Panama has greatly reduced ocean routes between the Atlantic and the Pacific Oceans.
2. Isolation: Surrounded almost on all sides by the oceans, the continent has been able to retain its identity as well as also remained free from involvement in world wars.
3. European Influence: Discovery of the continent as well as its achievements and rapid socio-economic progress are mainly contributed by the Europeans.
4. Developed Agriculture: North America has excellent farmlands. The Central Lowlands farm is the richest agricultural tract of North America. The Canadian Prairies are one of the greatest wheat-producing regions of the world. Corn, cotton, and tobacco are grown more to the south in the U.S.A. In central California, fruit growing is very important.
5. Forest Resource: The coniferous forests cover nearly half of Canada. Canada is the world’s greatest producer and exporter of newsprint and is second to the U.S.A. in wood pulp production. These forests are also the home of fur-bearing animals.
6. Resourceful fishing: Fishing is important in the continental shelf of the Atlantic and the Pacific costs, Canada is the third greatest fish exporting country in the world.
7. Mineral resources: North America is extremely rich in minerals and it leads the world in the production of iron ore, copper, lead, zinc, molybdenum, vanadium (U.S.A), silver (Mexico), and nickel (Canada and Cuba). It is also the fourth-largest producer of gold. It is also rich in coal, petroleum, and many other minerals.
8. Power Resources: The continent has abundant power resources such as coal, petroleum, natural gas, and falling water. The U.S.A. has almost one-third of the world’s coal reserves, 25% of the world’s Petroleum, and more than 25% of the world’s water power reserves while Canada has 14%. North America has also, rich of uranium which is the basis of nuclear fuels.
9. Developed Manufacturing Industry: The U.S.A. leads all other North American countries in manufacturing, Iron and steel, oil refining, aluminium, and copper has been made. Automobiles and machinery, meat packing, and food processing.
10. Developed transport and communication system: Roads, rail, and air routes crisscross the continent. The U. S. A. has about 25% of the world’s railroad mileage and about 38,400 km. of navigable waterways.
11. Skillful and enterprising immigrant population: These rich natural resources and a skilful and enterprising immigrant population have made North America the richest continent inhabited by some of the richest nations.
12. Tremendous Success: Success in education, science, technology, space, exploration, and even in world politics is responsible for its unlimited economic growth. In fact, the continent has become the focus of world political and economic power.

Chapter 9 North America: Physical Features of North America

Relief of North America: Landform of the continent of North America is very much diversified. Physiographically, the continent can be divided into five divisions—

1. Western Mountains or Cordilleras,
2. The Eastern Highlands,
3. The Canadian Shield in the North,
4. The Central Plains and
5. The Coastal Plains.

The Western Mountains or Cordilleras (Spanish ‘cordillera’ means rope or chain): Western part of North America is covered by the fold mountains that stretches from Alaska in the northwest to the Isthmus of Panama in the south about 6900 Km.

It extends along the Pacific Ocean coast, as such, it is also Pacific Mountains. It is the widest (about 1700 km) at the central part- where its altitude is not very high. But it is narrow in the north and in the south where the height of the mountain is relatively higher.

North-South extended three parallel mountain ranges have formed a cordillera:

1. To the extreme east, lies the longest, highest, and almost continuous range of the Rockies. They begin as the Brooks Range in Alaska and continue as the Mackenzie Mountains Selkirle Range, Rocky Mountains, and the Eastern Serra Modre. The northern part of Rocky mountain is. called ‘Endicott’ while the southern part is called ‘The Sierra Madre’.
2. To the west of Rocky, there is another range which is known as the ‘Alaska Range’ in the extreme north in Alaska, the coast mountains and the Cascade Range in Canada, Sierra Nevada Range in California, and the Western and Sn Sierra Madre in the extreme stuff in Mexico. Mt Mckinley (6194 m), an active volcano on the Alaska Range is the highest peak of the continent while Mt. Logan (5951 m.) in Canada is the Second highest. Mt. Whitney is the highest peak (4420 m) of the Sierra Nevada
3.  In the extreme west of the continent along the Pacific coast lies the third mountain range which is called St. Elias in the north in Alaska and as Coast Range in Canada —U.S.A.

“WBBSE Class 8 North America notes, Geography Chapter 9”

Plateaus of Western Mountains: In between the parallel ranges are located intermontane plateaus, such as

1. Yukon plateau between Endicott and Alaska range,
2. Columbian plateau located to the south-west of the Yukon plateau,
3. Idaho or snake plateau in the western part of the U.S.A.,
4. Great Basin to the south of it.
5. Colorado Plateau between Rocky mountain in the east and Sierra Nevada in the west and
6. Mexican Plateau further South in Mexico,
7. In the extreme south lies the plateau of Central America.

Valleys of Western Mountains: The Western Mountain Range consists of many broad river valleys. These are as follows:

1. Colorado Valley: The Colorado river flows through the world famous ‘Grand Canyon’ which is 446 km long, with 1600 m. depth in some places, and is the largest canyon of the world.
2. The Valley of California: The valley is located in between the Sierra Nevada and Coast Range.
3. Death Valley: The famous Death Valley’ is located to the southeastern part of Sierra Nevada. It is the lowest part of the continent (83 m deep below sea level). This region is the lowest-lying area, of the Western hemisphere and the hottest region (56°C) of North America. Due to the high temperature and salinity of stored water, no animal can live here. So this valley h is known as “Death Valley”.

Class 8 Geography Chapter 9

Important Passes: The important passes through the Rockies are the Yellow Head, Kicking Horse, and Crow’s Nest passes in Canada and the Yellowstone Pass in the U.S.A.

Volcanoes Western Mountains: There are many volcanoes, such as—Orizaba or Citlaltepetl (5610 m.) Popocatepetl (5465 m.) and Colima (3883 m). They are highly active volcanoes.

The Eastern Highlands: In the east of North America, the Eastern Highlands extend from Labrador in the north to Alabama in the south. It includes Greenland also.

These are much older, lower, and less rugged than the mountains of the Western Cordilleras. Their average elevation is not more than 1400 metres. These are made up of ancient crystalline igneous and metamorphic rocks, such as granite, gneiss, schist, slate, and quartzite.

“Class 8 WBBSE Geography Chapter 9, North America easy explanation”

These highlands run southwards from Newfoundland roughly parallel to the east coast. Their continuity is broken by the St. Lawrence Valley and the Hudson-Mohawk Gap. So, it consists of three isolated units—

1. Labrador Plateau in the north,
2. New England High Lands in the middle and
3. Appalachian Mountain along the Atlantic coast.

North-south extended Appalachian Mountain, also known as Atlantic Mountain’ it is an old fold mountain. Due to age-long denudation, it has been lowered than the Rocky mountain. Its western escarpment is called ‘Allegheny’.

Further west, lies the Cumberland Plateau. Eastern Section is called ‘Blue Ridge’. Mt. Michel (2038 m) of Blue Ridge is the highest peak of the Appalachian mountain.

The easternmost part of the Appalachians is called the ‘piedmont Plateau’. This plateau descends to the plain quite steeply and the east-flowing rivers form rapids and waterfalls as they tumble over the edge of the plateau, called the ‘fall line’.

These falls are used for generating hydel power. Blue Ridge and Piedmont plateau were formed in the Caledonian system about 50—40 crores years ago. Allegheny was formed in the Carboniferous period about 32 to 22 crores years ago.

“WBBSE Class 8 Geography Chapter 9 notes, North America PDF”

The Canadian Shield in the North: The Canadian Shield is the oldest part of North America. Surrounding Hudson Bay in the north lies the Canadian Shield which is also known as the ‘Laurentian shield’. It is made up of extremely ancient igneous and metamorphic rocks mostly granite and gneiss.

Slow sinking and erosion have lowered this area to nearly a plain or a peneplain (200—500 m) which is interrupted by the presence of occasional low hills (35—65m) such as Mesabi. During the Ice Age, the Canadian shield was severely scoured by ice. As a result the land was smoothened and numerous lakes were formed.

The Central Plains: The Central plains lie between the Rocky Mountains in the west and the Appalachian Mountain in the east from where the plains stop towards the centre of the continent. These plains made up 60% of the total area of the continent.

They form a great belt of horizontally bedded sedimentary rocks. The plan is also made up of eroded ancient rock in the north where lies the Great Lake Region comprising five lakes. In the south, it is made up of young alluvial soil.

1. To the northeast lies.
2. St. Lawrence River valley.
3. To the west is the Great Lake region,
4. Further west lies the Prairies and
5. To the south is the Mississippi river valley.

These plains are by no means low everywhere. They rise westwards until they are over 500 metres in the High Plains that lie among the foothills of the Rockies.

The Coastal Plains: There are also some coastal plains along the long coastline of the continent. The Arctic coastal plain in the north is much wide but remains ice-capped. Pacific coast. The Atlantic coastal plain extends up to the ‘fall line’.It is wider than the Pacific Plain. The wide coastal plain of the Gulf of Mexico extends northwards and merges with the Central plains.

Chapter 9 North America: Rivers Of North America

Many rivers are flowing through this continent making a network of rivers. These rivers are characterised by the following important features.

1. The Rocky Mountain in the west and the Appalachian Mountain in the east of the continent act as a ‘water divide’ from which many rivers have originated.
2. There are many long rivers, such as Mississippi-Missouri and there are also some short rivers, such as west-flowing rivers.
3. The rivers flowing to the east of the Eastern Highlands towards the Atlantic Ocean are short but the rivers flowing west of the Eastern Highlands are long. Again, the rivers flowing east of the Western Mountains are long but the rivers flowing west of the Western Mountains are short.
4. The rivers which are drained into the oceans are short but turbulent.
5. The rivers which flow towards the interior are long but their velocities are less.
6. There are some rivers which flow along a few lakes, i.e. St. Lawrence.
7. Most of the rivers of this continent are perennial.
8. There are a few inland rivers in this continent.
9. There are some rivers that form waterfalls and are suitable to generate hydel power.
10. Some navigable rivers are flowing in different parts of this continent which help to develop irrigation systems, transportation, and industrial and commercial progress.

Important Rivers of North America:

Types of the Rivers	Name of the Rivers
1. East-flowing rivers or rivers drained into the Atlantic Ocean.	1. Lt. Lawrence, Hudson, Delaware, Mohawk, Potomac, etc.
2. South-flowing rivers or rivers drained into the Gulf of Mexico.	2. Mississippi-Missouri, Rio-Grande or Rio-Bravo, Alabama, etc.
3. West-flowing rivers or rivers drained into the Pacific Ocean.	3. Columbia, Snake, Yukon, Sacramento, San Joaquin, Colorado, Fraser, etc.
4. North-flowing rivers or rivers drained into the Arctic Ocean and Hudson Bay.	4. Mackenzie, Nelson, Churchill, Chesterfield, Great Whale, Albany, etc.
5. Inland Rivers.	5. Saskatchewan, etc.

 

Based on variations in source, the direction of flow, the volume of water, and their mouth, rivers of North America can be grouped into the following five categories:

East flowing rivers or the rivers draining into the Atlantic Ocean:

1. St. Lawrence: St. Lawrence is the longest (4000 km) and principal river of this region. It rises in the highland west of lake Superior as the St. Louis river in Minnesota and flows through Superior, Michigan, Huron, Erie, and Ontario to drain into the Atlantic Ocean. It has formed the famous ‘Niagara Falls, 51 m high, between Erie and Ontario Lakes. The river is of great economic importance as it has connected the Great Lake Region with the Atlantic Ocean.
2. The Hudson: The Hudson (507 km) rises from the Adirondack mountains and flows south through a low narrow gap in the Appalachians. It meets the sea through the city of Newyork.
   
3. Delaware: The Delaware river (454 km) is originating from the Appalachian mountain flows southeastward and drains into the Atlantic ocean. The famous Philadelphia city is situated on the mouth of this river.
4. Mohawk(240 km): Mohawk is the largest tributary of the Hudson river It is formed by the junction of east and west branches in Oneida, and flows south and east into the Hudson river at Cohoes, above Troy.
5. The Potomac (465 km): This river is about 465 km long and originates from the Appalachian Mountain flows along the boundary between West Virginia and Maryland and empties into the Chesapeake Bay of the Atlantic Ocean. The capital of the U.S.A., Washington D, C. is situated on this river bank.

“WBBSE Class 8 Geography Chapter 9, North America important questions”

South flowing rivers or the rivers drained into the Gulf of Mexico:

1. Mississippi-Missouri: The Mississippi (3770 km) entirely a river of the U.S.A., is the longest as well as the largest river of North America. It rises in the highland, west of lake Superior, flows southward and drains into the Gulf of Mexico. Its principal tributary, Missouri meets the Mississippi about 16 km north of St. Louis. The combined flow of Mississippi and Missouri is the third longest (6210 km) river of the world. Other important tributaries of Mississippi areÿea0 Ohio, Arkansas and Tennessee.
2. Missouri: Missouri (3726 km), the greatest tributary of the Mississippi, originating from the Rocky Mountain in the West flows south-eastward and joins the Mississippi river. The famous ‘Great Falls’ has formed by the Missouri river. Missouri is a turbulent and muddy river. The river not only supplies huge quantities of water but also a large load of silt to the Mississippi. Yellowstone river, a tributary to Missouri, has formed many springs and geysers at Yellowstone, national park. There is the famous ‘Old Faithful Geyser’ from which hot water is ejected to a height of 60 metres at an interval of 90 minutes.
3. The Rio-Grande or Rio-Bravo: The Rio-Grande (3060 km), one of the longest rivers of North America, is a snow-fed stream. It rises from the Southern Rocky Mountains in southwestern Colorado and flows to the Gulf of Mexico marking the entire border between the U.S.A. and Mexico.
4. Alabama: This navigable river is about 510 km. It flows south-west ward and drained into the Gulf of Mexico.

“Class 8 Geography North America notes, WBBSE syllabus”

West flowing rivers or the rivers drained into the Pacific Ocean: These rivers rise in the Western Mountain and flow westward to drain into the. Pacific Ocean. They are short in length but turbulent and have formed deep gorges.

1. The Columbia (1967 km): The Columbia rises from the Selkirk Range- in British Columbia and flows through Canada for about 800 km and the U.S.A. for about 1200 km, it enters the Pacific Ocean at Astoria. There are many dams on this river of which the grand Coulee’ is the largest.
   
   
2. The Snake (1682 Km): The Snake is the largest tributary of the Columbia. In its lower course, the river passes through a gorge called the hells Canyon’. A maximum depth of 2400 metres makes it the deepest gorge of North America.
3. The Yukon(3190 km): The Yukon, the longest river of Alaska, rises from the Coast Range and flows first northwards and then westwards to enter the Bering Sea through Alaska. A major part of this river freezes in winter.
   
   
4. The Sacramento (615 km): The Sacramento is a south-flowing river which occupies the longitudinal valley of California. The river Sacramento and San Joaquin flowing from opposite directions join each other before entering the Bay of San Fransisco.
   
   
5. The San Joaquin (567 km): The San Joaquin river also occupies the longitudinal valley of California. It flows west and north-westward and before entering the Bay of SanFransisco it joins with the Sacramento river.
6. The Colorado (2349 Km): The Colorado river rises in the Rocky Mountains of Colorado in the U.S.A. and for 27 km marks the international border between the U.S.A. and Mexico. It drains a largely arid and semi-arid region of the West U.S.A. and Mexico. Finally, it enters the Gulf of California in Mexico. The river along with its tributaries has formed a labyrinth of narrow Canyons which are more than 1500 metres deep. The longest of these Canyons through which the main river flows is the spectacular ‘Grand Canyon’.|t is 446 km long and in places, more than 1600 metres deep. It ranges in width from 200 metres to 29 km.
7. The Fraser (1377 km): The Fraser is the chief river of British Columbia. It flows between the Rocky and Caribou ranges and meets the sea south of Vancouver. It is famous for salmon fisheries and is an important shipping route.

“WBBSE Class 8 Chapter 9 Geography, North America solutions”

North flowing rivers or the rivers drained into the Arctic Ocean and Hudson Bay:

1. The Mackenzie (1650 km): The Mackenzie is an important river of Canada that flows out of the Great Slave Lake, and after draining northward through the western part of Canada, falls into the Beaufort Sea of the Arctic Ocean. A major part of the lower course of the river remains snowbound from October to June. If the Peace river which enters the Great Slave is considered a part of the Mackenzie, the total length of the river will be 4241 km.
2. The Nelson (648 km): The Nelson river flows out of the North Lake of Winnipeg through several lakes of North-East and falls into the Hudson Bay at Port Nelson.
3. The Churchill: This river is about 1600 km long and rises in Lake la Loche in northwest Saskatchewan, flows eastward across Saskatchewan and northern Manitoba and turns northeast into Hudson Bay at Churchill.
4. The Chesterfield: This is an inlet, of Hudson Bay. It rises from the north of the central plain of North America flows towards the north and falls into Hudson Bay.
   
   
5. The Great Whale: This is a river of central and western Canada. It is about 373 km long. It flows westward and enters the southeast of Hudson Bay.
   
   
6. The Albany: This is a river of north-central Ontario of Canada. It is 988 km long and rises in the chain of lakes (largest St. Joseph) in West Ontario and flows east and northeastward into West James Bay at Fort Albany. In winter the water of this river is frozen.

“WBBSE Geography Class 8 North America, Chapter 9 key concepts”

Inland Rivers of North America:

There are a few inland rivers, the course of which are restricted within the continent. River Saskatchewan an inland river.

The Saskatchewan(1939 km):

The Saskatchewan river is an inland river that rises in the eastern slope of the Canadian Rocky Mountains. The meaning of the word ‘Saskatchewan’ is the ‘rapid river’. It flows eastward for 550 km to enter Lake Winnipeg. The river is widely used for the generation of hydel power and irrigation.

Lakes of North America:

There are many lakes in different places of North America. Though most of the lakes are located in the northern part of the central plains, a few lakes are found in the mountain land also. So, the lakes of North America are of two types according to their location.

These are as follows:

1. Lakes of the Plainland: In the northern part of the central plains are located five famous lakes Superior, Michigan, Huron, Erie, and Ontario. These are freshwater lakes. Lake Superior is the largest lake in North America and the second largest lake of the world (The Caspian sea is the largest), as well as the largest freshwater lake of the world. These five lakes are interconnected through the St. Lawrence river and have formed the ‘Great Lakes’ Many freshwater lakes are also found in Canada, such as Winnipeg, Great Bear, Great Slave, Athabasca, Reindeer etc.
2. Lakes of Mountainland: In the western mountains there are saltwater lakes. Such as the Great Salt Lake and the Lake Nicaragua. Among the saltwater lakes of North America the ‘Great Salt Lake’ is the largest.

Chapter 9 North America: Climate of North America

North America has a great variety of climates. The climate of North America is very much, diversified and controlled largely by the following factors:

1. Latitudinal Extent: North America mainly extends from the tropical latitudes (in the South) to the frigid zone (Arctic region in the north) and thus, in general, temperature decreases from south to north.
2. Alignment of the mountains: The north-south trend of the Western Cordilleras and the Appalachians cannot obstruct the winds blowing from the north and south. So the very cold polar winds enter the continent in winter and this results in frozen water surfaces even as far south as New Orleans.Similarly, the absence of any barrier permits warm winds to enter the land from the south throughout the year. In winter these winds make the temperature moderate by rising it, and in summer create ‘hot waves in the interior parts of the southern U.S.A.On the other hand, the Western Cordilleras act as an effective barrier to the warm westerlies. These rain-bearing winds blowing in from the Pacific drop much of their moisture on the Western slopes of the mountains. So the eastern slope remains nearly dry and in places have deserted.
3. Distance from the Sea: By virtue of its vast size and extent, the interior part of the continent is far from the sea, as such extreme condition prevails in the interior of the continent. Nearly the whole of the northern part of the continent freezes in winter but becomes quite hot in summer.
4. Ocean current: Ocean currents also have a great influence on the climate of North America. The California current in the southwest and the Labrador current in the northeast are cold currents. They produce a cooling effect on the adjoining coastal areas. In the southeast, the Gulf stream and in the northwest, the Alaskan current are warm currents. As a result, the climate of the coastal areas becomes warmer.
5. Altitude: The effect of altitude on climate is experienced in the Western Cordilleras that remain snow-covered in winter.
6. Wind: The westerlies bring heavy rain to the west coast throughout the year while the Trade winds bring heavy rains to the southwest coast.

Due to the above factors the climate of North America is full of diversity.

“WBBSE Class 8 Geography Chapter 9, North America summary”

Seasonal conditions of the important elements of climate in different parts of North America:

Temperature: In summer, (May to October) temperature decreases from the southeast (maximum 32°C) to the north,(below freezing point). In Winter, (November to April) due to the presence of cold polar wind, the temperature even in the southern part of the continent remains low (16°—20°C)

Air Pressure and Wind: In summer, low pressure develops in the southern part of the continent due to high temperatures. Therefore, moist monsoon wind blows over this region. In winter, high pressure develops over the northern parts of the continent due to severe cold. Therefore, the cold Polar wind blows here.

Rainfall: Heavy rainfall (100-200 cm annually) occurs in the northwest coast; the south-eastern and central part of the continent. Moderate rainfall (50 to 100 cm, annually) in the southern part of the west coast and in the central plains of the continent. The least rainfall (less than 25 cm annually) occurs in the southwestern part of the continent where a number of hot deserts have formed.

 

 

Class 8 Geography Chapter 9

Climatic Regions of North America: Based on variations in temperature, rainfall,air pressure, and wind, the continent of North America can be divided into ten c ima c r These are as follows:

1. Arctic (very cold) or Tundra Climatic region.
2. Cold Temperate Interior or Taiga Climatic region.
3. Cold Temperate Eastern Margin or Laurention climatic region.
4. Cold Temperate Western Margin climatic region.
5. Cool Temperate continental type of climatic region.
6. Temperate Desert climatic region.
7. Hot Desert climatic region.
8. Warm temperate East Margin or China type of climatic region.
9. The Mediterranean climatic region, and
10. Tropical Hot and Humid climatic region.

 

Climatic Type	Location	Characteristics
Arctic (Very cold) Tundra Region	Northern parts of North America, Alaska in the west Labrador in the east, and in Greenland.	(1)Winters exists for 8-9 months throughout the year (2)Snowfall and Blizzards are common in winter (3)Rainfall occurs due to temperate cyclone only in summer.
Cold Temperate Interior (Taiga)	From British Columbia of Canada towards the south of Thunder region to Newfoundland.	(1)Summer is short, (2)Heavy snowfall in winter and (3)Scarcity of rainfall is the main characteristic of this climate.
Cold Temperate Eastern Margin	The north-eastern part of the continent.	Moderate rain, (100-150 cm.) longer cold winters, and mild Summer occurs throughout the year. Temperate Cyclone occurs seldom.
Cold Temperate Western Margin	North-west coast of the continent.	Summers are pleasant and winters are mild. Heavy rainfall (100 – 200 cm.) occurs throughout the year. The sky remains cloudy.
Cool Temperate Continental climate	The central part of the continent, the Rocky Mountains, and the middle part of the Great lakes.	Though summer is very hot, winter temperature is often below freezing point. So the climate is extreme. Another name of this climate is the Prairie climate.
Temperate Desert climate	Eastern slopes of the Western Mountains of North America.	(1)It is a rain shadow area. (2)Rainfall is low. (3)Winters are severely cold.
Hot Desert climate	Sonorom desert, California is west to Mexico in the east.	Due to scanty rainfall deserts are formed in a vast areas. Summer is long, hot, and dry.
Warm Temperate	Mississippi plains, East coast region, Lake Region to entire eastern highlands.	The summer climate is hot. Rainfall occurs throughout the year due to S. W. Westelies Coastal region being cool in winter.
Mediterranean type of climate	California, a coastal region in the southwest part of the continent.	(1)Rainfall occurs in Winter due to S.W. Westerlies, (2)Summer is dry, (3)Moderate comfortable climate and sunny weather are found throughout the year.
Tropical hot and Humid type of climate	The southern part of Florida and the West Indies, are countries of middle America.	(1)Climate is hot and humid. (2)Rainfall occurs throughout the year like equatorial region. (3)Sometimes tropical cyclones (Hurricanes) occur here.

Chapter 9 North America: Natural Vegetation Of North America

Natural vegetation belts are always closely related to the different types of climate. As North America has a variety of climates, so it has a great variety of natural vegetation. The natural vegetation of North America can be divided into the following types.

1. The Tundra Vegetation: The extreme north of the continent is known as the Tundra or the cola desert region. This region lies along the northern coast of Canada from Alaska to Labrador. It is very cold and remains frozen throughout the year.That is why this region is known as “permafrost” or permanently frozen subsoil. Here the winters are long and cold and summers are short. The snow melts during the short summer. Its vegetation includes mosses, lichens, grasses, dwarf bushes, and arctic flowers. Reindeer, polar bears, musk-ox and caribou, etc. are the chief animals of this region.
2. The Taiga or the Coniferous Forest Belt: To the South of the Tundra lies a wide belt of coniferous forests known as the ‘Taiga’. This wide belt runs from the Atlantic to the Pacific across Canada. Here the winters are severe and the summers are warm, coniferous forests are widespread and provide softwood as such the forest is also called ‘softwood forest’.Pine, Far, Spruce, and Larch are important trees and these are well adapted to the climate of this region. The trees have tough, narrow needle-shaped leaves, dark green in color. Fur-bearing animals such as boar, silver fox, beaver, mink, lynx, etc. are the common animals of this forest.
3. Temperate Mixed Forest Belt: The temperate mixed coniferous and broad-leaved Deciduous Forest region lies to the southeast of the Taiga (coniferous forest). The region extending from Lake Region in the north to the Eastern High land is occupied by deciduous trees like oak, maple, elm, ash, beach, and Douglas fir.The trees are mainly of the hardwood type and broad-leaved varieties. In autumn the .leaves become reel, yellow or orange color and the trees shed their leaves, as such Autumn is called here as ‘Fall’. Among the coniferous trees are include pine, fir, and cedar trees. They yield softwood. Much of the original forests have been cleared for the growth of the dense settlement. Crops are grown in those areas.
4. The Tropical Rain Forest: The main areas of Tropical Rain Forest are along the Gulf coast of the U.S.A and Florida. West Indies and the southern coast of Mexico are hot(26C) and get more than 150 cm of rain. So dense evergreen forests of hardwood trees cover these regions. The natural vegetation includes pa|mS/mahogany, logwood, the famous yellow pine, and cypress. Lowlands and slopes of this region have been cultivated intensively and various crops such as graphs, sugar cane, and rice are produced. Large tracts of land near the coast have been opened up for banana plantations.
5. Temperate or Midland Grassland: Temperate grassland is the vegetation of the great centra I plains. These regions have very light rainfall, too low for proper growth of trees; so only tall grass grows. The natural vegetation of this region consists of almost treeless grasslands, called ‘Prairies’. Central part of the continent between the Rocky mountain in the west and the Great Lake Region in the east is occupied by this vast grassland of temperate latitudes in the interior of North America. This region is now cultivated and forms a vast wheatland. In other parts. Barley is grown. Cattle farming is the main occupation of the people of this region.
6. The Mediterranean Vegetation: This type of vegetation is found on the West Coast of California. Here summers are hot (25°C) and dry, while winters are wet and cool (10°C). This type of vegetation is drought-resistant evergreen trees and shrubs. These are specially adapted to face the hot and dry summer. The trees have small, glassy, waxy leaves which prevent transpiration and long tap-roots which reach deep underground. They have also bulky trunks and thick bark to store moisture and to withstand the dry summers. Some of the main trees which grow in this region are olive, cork-oak, laurel, and Mediterranean pine. Other trees include figs, citrus, and vine. Fruits like grapes, oranges peaches, apricots, and lemons are also cultivated in this region.
7. Warm Temperate Vegetation (The Sub-Tropical Hardwood Forests): These types of forests are found in the southeastern U.S.A. Here summers are hot (above 27 C), winters are cool (7°C to 13°C) and rainfall varies from 100 to 150 cm. The important trees include the long-leafed yellow pine and palms. The ‘Everglades’ or the swampy areas of Florida have mangrove trees. Here the trees have stilted roots to keep them above the level of the saline seawater.
8. The Mountain Vegetation: This type of vegetation is found mainly in the western and eastern mountainous regions of the continent of North America. The effect of altitude on climate is experienced in the Western Cordillera and Eastern Highlands that remain snow-covered in winter. Due to the decrease of temperature, the characteristics of vegetation is changed As such in the high altitudinal region there is coniferous trees are available.
   
   
9. The Vegetation of Hot Deserts: The Desert region lies on the plateaus enclosed between the main eastern and western ranges of the cordilleras in North Mexico and Arizona in the U.S.A. Because of the poor rainfall (below 25 cm) hardly any vegetation grows in these deserts. Cactus is the main vegetation, Prickly pear Joshua trees survive with the aid of dew in places where there is slight rainfall. Scanty grass, sage bush, and thorny scrubs also grow in hot deserts.

Chapter 9 North America: Prairie Grassland

An extensive treeless level grassland of North America is called ‘prairie’. French ‘prairie’ meaning a tract of meadows, occupies a great triangle in the heart of the continent. The prairies are the mid-latitude temperate grasslands of the central United States and Canada and extend from Alberta, Saskatchewan, and Manitoba in Canada, southwards through the Dakotas, to Kansas, Oklahoma, and Texas. The Prairie grasslands have the following distinguishing features.

1. These lie in the interior of the continent.
2. These are environmentally very important and represent a distinct kind of biome.
3. These are remote from maritime influence.
4. The heartlands of these grasslands are practically treeless.
5. The grasslands have distinctive wet and dry seasons. Droughts are common and frequent.

The climate of this region is ideal for grass to grow. Here the temperature ranges between 15°C and 25°C. In winter temperatures may go much below freezing points as in Winnipeg in Canada. There is summer rainfall.

The rainfall varies between 20 cm to about 70 cm and the average rainfall is about 50 cm/per year the winters are fairly dry, with just a little snow in the north. Large areas of the Prairies have been plowed for cereal production, and the wetter eastern parts are very productive. The drier western prairies, where the grass is shorter, are less productive.

These grasslands lie in the zone of Westerlies. Since then lie in the interior, the westerlies lose the moisture content by the time they reach this region. Therefore the amount of rainfall is low. The wind velocity is high in the grasslands because there are no trees to obstruct them.
Local winds are also important.

“WBBSE Class 8 Geography Chapter 9 North America, definitions and examples”

The climatic conditions ensure fairly regular growth of grass with variations due to the change of seasons. The rainy season makes the dormant grasses sprout with tender shoots. These are nutritious and realized by animals.

When the dry season approaches, the grasses start bearing a brownish look and by the autumn season, they are completely dried. Grasses now become dormant and are better able to face the drought on the one hand and the frost and snow on the other.

The higher western part called the high Plains’ has less than 50 cm of annual rainfall. This supports short grasses and is noted for livestock farming. The High Plains form the short grass prairies while the eastern part receives above 50 cm of rain forms the long grass prairies. These have now been converted into wheat lands. Hay, clover, and Alfalfa grasses are grown here.

So this grassland is famous for grazing grounds. For reason, dairy farming is developed here. For the conservation of dairy products modern refrigeration systems have been built here. It is one of the world’s very fertile plains. Therefore, besides the rearing of animals, the raising of crops like wheat, barley, oats, etc. have become highly important in these areas.

The hot local winds of chinook ascend from the Pacific coasts and then ascend to the Prairies; it melts snow and raises winter temperature. This condition makes even agriculture possible in the winter months of this region.

This is suitable, for wheat production. So this region as spring wheat belt’. The leading wheat-growing states in the U.S.A. are North and South Dakota, Minnesota, Montana, Iowa, and Wisconsin. In the southern part of the spring wheat belt wheat cultivation is practiced in winter. As in different seasons wheat is cultivated sufficiently in this region it is called the “Breadbasket of the World”.

Chapter 9 North America: The Lake Region Of North America

Introduction: The Lake region is one of the most important and prosperous regions of the e US.A. well as North America. A little to the north-east of the continent of North America, near the borders between the U.S.A. and Canada, there are a wonderful series of great five lakes—

1. Superior,
2. Michigan,
3. Huron,
4. Eric and
5. Ontario.

‘Great Lakes’ and along the southern shores of the ‘Great Lakes’ lies the country s greatest industrial district—the Lake Regions of the U.S.A.

Class 8 Geography Chapter 9

Location: The Lake Region of the U.S.A. is located in the Eastern part of North erica. This region extends between 41°N and 50° N latitude, and between 75°W and 93°W longitude.

The Lake Region of the U.S.A. comprises of the greater parts of the eight states of the U.S.A. t at one adjacent to the lakes. The eight states of U.S.A. that extend around the lakes are—

1. Minnesota,
2. Wisconsin,
3. Illinois,
4. Indiana,
5. Michigan,
6. Ohio,
7. Pennsylvania and
8. Newyork

Area: Lake Region of the U.S.A. covers an area of nearly 7 lahks 64 thousand square Kilometres. The area of the total water bodies of these lakes is 2 lakh 50 thousand Square kilometers. West to east extension – 1370 km and North to South extension – 1125 km.

Physiographic Characteristics: The Lake region of the U.S.A. is extensively flat land. It belongs to the central plains of North America. At some places it is an undulating plain (average height less than 180 meters), because of glacial depositions of stones and pebbles. There is a steep escarpment (75 m) between Erie and Ontario lakes. World famous Niagara Falls (51 m) has been originated in between the Erie and Ontario lakes.

Rivers: Principal river of this region is the St. Lawrence. It flows eastwards through the lakes and finally drains into the Gulf of St. Lawrence. The river is known as St. Marie between Lake Superior and Huron, St. Claire between Huron and Eric, the Niagara between Erie and Ontario Lakes, and St. Lawrence Seaway between Lake Ontario and Montreal.

Origin of the Lakes: The region is the most valuable gift of the ice Age to North America. In Ice Age North-eastern part of the USA is actually a lowland that was covered by Ice sheets. When this ice melted, waters of all these lakes were drained either to the Hudson Bay through Mohawk or to the Gulf of Mexico through Mississippi rivers, because then St. Lawrence was still frozen.

After the melting of the ice of St. Lawrence, the waters of these five lakes started to drain through the St. Lawrence river into the Atlantic ocean. Due to prolonged erosion, these vast snow-covered regions have been transformed into basins.

“WBBSE Class 8 Geography North America, revision notes”

Gradually this basin has been fulfilled with melting water and transformed into the great lakes. There are five lakes on the course of the St. Lawrence river. These are—superior (largest, 82500 Sq. km) Huron, Michigan, Eric, Ontario and they are popularly called ‘Five Great Lake’.

Climate: The climate of the Lake Region is a cool temperate type. Pleasant summer temperature varies between 17°C and 23°C severe cold. Winter temperature varies between – 3°C and – 13°C, as cold winds from the north blow in. As a result, rivers and lakes become ice-bound. Extensive snowfall covers the whole region in winter. Rainfall occurs mostly in summer and it varies annually between 75 cm and 80 cm.

Natural Vegetation: The natural vegetation consists of hardwood deciduous trees like maple, oak, ash, and hickory mainly found in the south. Coniferous trees like pine, spruce, and birch are also found in the north of this region. Most of the forests have been cleared to make way for mixed farming, industrial development, and dense settlement.

Soils: The region is mostly covered by fertile glacial soil. Grey-brown-podsolic soil which is moderately fertile also covers some parts. Fertile black soil or chernozem occupies most of the Lake Region of the USA. In this region infertile soils are also found which are mixed with stones, rocks, etc.

Chapter 9 North America: Economic Environment Of The Lake Region

Agriculture: The Lake Region of the U.S.A. is well-developed in agriculture because of its

1. Flat land,
2. Adequate rainfall,
3. Fertile soils,
4. The modern and scientific method of cultivation.

Large quantities of wheat, corn, barley, oat, oilseed, and beet are produced. Hay, and clover, are also grown as fodder crops in this region. This region is also ideal for mixed farming.

The cultivation of this region is practiced mainly by ‘crop rotation’ (Instead of producing a particular crop again and again, different crops are cultivated by rotation).

Grape, apple, and peach are also produced in this region. Central highland is famous for the highest maize-producing region of the world. So the Lake Region leads first position in the world for maize production.

Livestock Ranching: In the northern part of this region different grasses, like Hay, Clover, Alfalfa, etc. are cultivated for cattle feeding. So this region is developed in dairy farming and known as the ‘dairy belt’ of the U.S.A.

Sheep and pigs are also raised here. Wisconsin is famous for its daring and is known as the ‘Dairy state’. Chicago is famous for its meat production and is known as the ‘largest slaughter House of the world”.

The reasons for the development of livestock farming in this region are as follows:

1. Hay, clover, and Alfalfa grasses are grown here sufficiently which supply food for cattle.
2. A sufficient supply of water from the lakes.
3. The extensive plainland of this region is favorable for grazing.
4. The cool temperate climate of this region helps to preserve the milk, meats, and different dairy products.

Mineral Resources: The Lake Region of the U.S.A. is enriched with mineral resources. Varieties of minerals in large quantities are produced here, such as

1. Iron ore (About 75% of the U.S.A.) comes from the areas south and west of lake Superior—Mesabi (the largest Iron ore mine of the USA). Vermillion, Gogebic, Marquette and
2. Menominee.
3. Copper ore—Cuyuna,
4. Coal—Illinois and Indiana,
5. Petroleum—Illinois and Michigan,
6. Rock Salt—Ohio and Michigan.Other minerals include
   
7. Limestone,
8. Gypsum,
9. Zinc,
10. Lead and
11. Manganese

Transportation System: The transport system is very developed in the Lake Region. Other than railways, roads,s and airways are also specially developed. The economic development of the Lake Region is mainly due to the cheap transport through St. Lawrence.

The Niagara falls area is not navigable but there is a separate canal constructed around this. Eg. the Weyland canal allows ships to travel freely.

It is also noted that Chicago is one of the busiest airports in the world and is also the largest railway junction in the U.S.A. The Great Lakes and the St. Lawrence river together constitute one of the greatest inland waterways of the world.

Industry: The Lake Region of the U.S.A. is not only the leading industrial belt of North America but this is the most developed industrial region of the whole world. This Lake Region has become the greatest Industrial Region of the world with the help of the following causes:

1. Local Iron-ore: Large quantities of rich iron ore obtained from the Lake Superior mines Vermillion, Mesabi, Marquet, Menominee, etc. via the Great Lakes, and from Labrador via, St. Lawrence Seaway.
2. Nearby Appalachian coal: The vast coalfields of Pennsylvania, West Virginia Eastern, and Western Interiors are all nearby and provide fuel.
3. Developed Transportation System: The Great Lakes St. Lawrence waterways, the Eric canal that connects the finance capital cum port of New York via the Hudson river, the noise canals that join the Mississippi system, and a dense network of rail and roadways provide excellent transport.
4. Raw Materials: Large quantities of iron ore, limestone, manganese, lead, zinc, and gypsum are also mined locally. Petroleum is supplied from the oil fields of Pennsylvania, West Virginia, Michigan, and Illinois. Corn, meat, hides, dairy products, and timber from softwoods provide raw materials for industries based on agriculture.
5. Sufficient Hydroelectric Power: Sufficient hydroelectric power is gained from the strong current river and Niagra falls.
6. Dense population: The high density of the population provides plenty of skilled labor and a vast market for industrial products.
7. Freshwater lakes and Water of St. Lawrence: Salt-free or clean waters of the ‘Great Five Lakes’ and St Lawrence river are used in industry as well as drinking water.
8. Animal Products: Local animal products (milk, meat, hides, etc.) also help to develop different industries.
9. Coniferous Softwood: Timber from coniferous softwoods provides raw materials for the paper industry etc.
10. Sufficient Capital and High Technology: Abundance of capital and use of high technology.
11. Labour: Due to dense population sufficient skilled and general labors are available.
12. Market: The high density of the population provides plenty of a vast market. The region’s common frontier with Canada also helps it by enlarging the market.

Important Industries and Industrial Centres of the Lake Region of the U.S.A.:

Name of Industries	Important Centres
1. Iron and Steel Industry	Chicago, Gary, Buffalo, Duluth, Cleveland, Eric, Milwaukee.
2. Engineering Industry	Detroit, Chicago, Milwaukee, Toledo, Cleveland. Detroit is the largest automobile industry in the world.
3. Chemical Industry	Duluth, Akron, Chicago.
4. Meat Industry, Processing	Chicago
5. Leather Industry	Milwaukee
6. Oil refinery and Petrochemical Industry	Chicago, Buffalo, Cleveland, Duluth.
7. Paper Industry	Chicago, Greenbay, Buffalo, Rapids
8. Flour Industry	Buffalo, the world’s largest flour mill.
9. Cement Industry
10. Rubber Industry	Akron (Rubber capital of the world) Indianapolis.

 

Population and Cities: Economic prosperity of the Lake Region is responsible for the dense population and growth of many large cities. Important cities of the Lake Region are—

1. Chicago,
2. Duluth,
3. Toledo,
4. Detroit,
5. Milwaukee,
6. Cleaveland and
7. Buffalo

Chicago: It is located on the southern shores of blue Michigan in the state of Illinois. It is the largest city and leading industrial center in the Lake Region. This city is called a windy city because gusty winds has given this city nearly throughout the year.

As it is a large meat processing center it is called the largest slaughterhouse of the world. It is also the largest terminal railway junction and busiest airport in the world with a maximum number of flights.

Duluth: It is located on the western shores of lake superior in the state of Illinois. It is an important center of the iron and steel industry and also a large city and port.

Detroit: Situated on the banks of the St. Clair river. It is the largest center of motor vehicles in the world.

Toledo: Lying on the western shore of lake Erie, it is a center of engineering and chemical industries, etc. Milwaukee, Cleaveland, and Buffalo, etc. are the important industrial cities of this region.

Chapter 9 North America: The Canadian Shield Region

Introduction: The word ‘Shield’ refers to an ancient landmass of an undulating surface formed by hard rock. There are eleven important shield regions all over the world. Among them, the Canadian Shield is the largest.

An ancient plateau or a highland of hard rock located in the northeastern part of Canada and bordering the Hudson Bay on the east, west, and south is called the “Canadian Shield”. This is also known as the “Laurentian Shield”.

Location: The Canadian shield region latitudinally extends from 42° north latitude (from the south) to 82° North latitude (in the north) and longitudinally it extends from 52° west longitude (in the east) to 120° west longitude (in the west).

Boundary: It extends from the Labrador plateau in the east to the shores of the Great Bear, Great Slave, Athabasca, and Winnipeg lakes in the west and from the shores of the ‘Five Lakes’ in the south to the Arctic Ocean in the north.

Area: The Canadian Shield Region covers an area of about 5-2 million square kilometers.

Physiography: The Canadian Shield region is a part of the world’s most ancient landmass. The land is a rolling peneplain with an average height of 200 to 500 meters.

This shield is very old hard rocks were scraped bare of soil by glaciers during the Ice Age. The glaciers with rock debris froze into them. Innumerable lakes found on its surface are actually the results of glaciation.

It is mostly made up of hard granite and gneiss. To the east, the shield is about 900 meters high. In some places of this region due to erosion, a few depressions had been developed in the surface causing the origin of lakes in such areas as Athabasca, Great Bear, Great Slave, etc. The slope of the region is from south to north.

“Class 8 WBBSE Geography Chapter 9 North America, multiple-choice questions”

Rivers and Lakes: The rivers of the Canadian Shield region flow from south to north and drain out at Hudson Bay. The rivers are Albany, LaGrande Saskatchewan, Mckenzee, Nelson, and Churchill.

St. Lawrence is the most important river and marks the south boundary of the region. Many of the rivers of this region have large waterfalls or rapids which are tapped to generate hydel power. Many lakes, which are located side by side, are connected by these rivers.

Climate: The region has very long cold winters with heavy snow and summers. Rainfall averages 40 cm in the west and rises to over 80 cm in the east. temperature varies between 10°C in the North to 16°C in the South. Nort ern pa region is under the severely cold Tundra climatic region.

Soil: The soil cover of this region is very thin. In some areas, glaciers deposited unsorted materials like boulders, gravel, sand, and sticky clay in sheets to form drift plans on the lowland. These drift plains are generally fertile and are good for mixed farming.

Natural Vegetation: No large trees cannot exist except moss lichen, algae, and small shrubs in the north where the Tundra climate prevails. Coniferous trees like pine, spruce,fir, etc. grow in the south. Mixed forests of coniferous trees and deciduous trees like oak and maple are found in the southeastern part of the region.

Animals: Wild animals like reindeer, wild cat. white fox, beaver provide urs are found here.

Chapter 9 North America: Economic Environment Of The Canadian Shield

Agriculture: The Canadian Shield region is not very suitable for agriculture due to

1. Short summer,
2. Severely cold climate,
3. Infertile soil and sparse population.Farmers produce
   
4. Wheat,
5. Barley,
6. Oats,
7. Potatoes,
8. Flax and
9. Vegetables only in the fertile glacial clay belt around Hudson Bay and in the St. Lawrence river valley.

Lumbering: In summer after the melting of ice, the timber easily reaches to sawmills through the river currents. Lumbering is well developed in this region as well as Canada due to the abundant supply of timber.

Fishing: Fishing is commercially practiced in as many as 600 lakes.

Animal Rearing: Animals like sheep and cattle are also reared in the same area.

Mineral Resources and Mining: The Canadian Shield region is most important for its minerals. This region is the richest mineral field of North America. Sudbury supplies about half of the world’s nickel output. Important minerals produced in this region include.

1. Nickel	Sudbury (World’s largest 50% nickel mine), Thompson.
2. Copper ore	Sudbury and Noranda district, Timinis.
3. Gold	Porcupine, Kirkland, Noranda, Rouyn, Timinis, and Yellowknife
4. Iron-ore	Schefferville and Wabush city on the Labrador-Quebec border.
5. Uranium	Uranium City and Port Radium.
6. Lead	Flin Flon; Pine Point, Noranda.
7. Zinc	Flin Flon, Pine Point, Noranda.
8. Cobalt	Sudbury region. Thompson, Sherridon.
9. Silver	Flin Flon, Sudbury, Thompson, Sherridon
10. Platinum	Sodbury, Thompson, Sherridon.

 

Class 8 Geography Chapter 9

The Canadian Shield also ranks first in asbestos, second in magnesium and third in silver production in the world. Timinis is the second largest goldmine in the world. Though this shield region excavated many minerals but mining activities are restricted greatly here due to some factors. These are as follows:

1. Adverse climatic conditions,
2. Sufficient manpower,
3. Great Expanse
4. Few ice-free navigable rivers and
5. The lack of transport facilities, partially in the northwest.

Industry: Though this region is sparsely populated and agriculture but there are some factors that have led to the growth of many industries. These are as but there are some factors which have led to the growth of many industries.

These are as follows—

1. Availability of fur, softwood, good pastures, and minerals.
2. Hydel power is generated from the local rivers.
3. Cheap water transport and good air transport.
4. A sufficient supply of labor.
5. The assistance of high-quality Canadian technology.
6. Sufficient financial patronage.

With the help of these factors, in the southern part of the Canadian shield region, different types of industries have been agglomerated forming the basis of economic prosperity in this region.

Name of the Industry	Producing Centres	Products
1. Paper Industry	Pine Point, Thunder Bay, Winnipeg, Ottawa, Montreal	Paper, Paper Pulp, Newsprint.
2. Lumbering Industry	Ottawa, Porcupine, Quebec	Wood and wood pulp.
3. Dairy Industry	Quebec	Milk dairy products and butter, cheese, paneer
4. Fur Industry	Winnipeg, Toronto, Montreal	Leather-based apparels
5. Rayon Industry	Toronto, Montreal, Ottawa	Different sophisticated materials
6. Iron and Steel Industry	Sault St. Marie.	Iron and steel
7. Engineering Industry	Montreal, Ottawa, Quebec	Different types of machinery and electronic gadgets
8. Metal Industry	Ontario, Alberta	Different types of metals

 

Timber and Paper Industry: The Canadian Shield region is developed in Timber and paper industries. There are some factors that have led to the growth of these industries.

These are as follows:

1. There is an extensive coniferous forest that grows over this region which is the worlds second-largest in size(after Russian Taiga)soft timber of this forest is the main raw material of paper industry.
2. The logs are collected by the river current cheaply.
3. This region is developed in hydel power by swift-flowing rivers.
4. Modern machinery helps to develop this industry.
5. Supply of efficient labor and
6. Sufficient financial patronage.

“WBBSE Class 8 North America notes, Chapter 9 worksheet”

Due to the above factors, the Canadian Shield region is well-developed in Timber and paper industry.

Population: Because of the extremely cold climate Canadian Shield region is sparsely populated. Eskimos live in the northern part of the region.

Major Cities: Important cities of the Canadian Shield region.

Ottawa(1 million in 2001): Ottawa on the Ottawa river, a tributary of St. Lawrence, is the capital of Canada.

Thunder Bayon Lake Superior, Sudbury on the Huron, and Churchill on the Hudson Bay are important cities. Sault St Marie, Winnipeg, and Thompson, etc are also important cities.

WBBSE Notes For 8 Class Middle School Geography

Chapter 6 Climate Regions

Climate Regions Meaning:

The climate is the aggregate of atmospheric conditions over a wide area or a time (Say at least 35 years). The natural division of the earth according to e characteristic features of climate is called a ‘Climatic region’. There is a certain world each of which has its own climatic characteristics especially, identical emp rainfall conditions.

Again, temperature and rainfall play a great role in natural vegetation type and human activities. A climatic region, thus, includes an area that as a m natural vegetation and a human lifestyle.

Read and Learn all WBBSE Notes For 8 Class Middle School Geography

The characteristics of Climatic Regions: The characteristics of climatic regions are as follows:

1. A climatic region, generally, spreads over the different parts of the earth’s surface and is almost similar in respect of the climatic condition
2. The boundary or the limit of a climatic region is not definite. It gradually changes to another climatic type.
3. For the difference of the geographical location, landform, and soil character, some dissimilarities may be found in a particular climatic type and therefore sub-divisions may be referred to.
4. The limit or boundary of a climatic region does not depend on man’s discretion. A change in the political condition does not affect the boundary of a climatic region.
5. Soil, natural vegetation, biodiversity, and even human lifestyle vary with climatic regions.

The Major Climatic Regions of the World:

Climatic Zone	Latitude	Climatic Type
1. Equatorial or Hot-Humid Climatic Zone	0°  – 10°  N and S	1. Equatorial Climate
2. Torrid Zone or Tropical Zone. (Warm Climate)	10° – 30° North and South	2. Tropical Monsoon Climate.3. Tropical Savanna Climate (Sudan type).4. Tropical Hot Deserts Climate.
3. Warm-Temperate Zone	30° – 45° North and South	5. Mediterranean Climate (Western Margin). 6. Steppe type or Central Continental type.7.    China type of Climate (Eastern Margin)
4. Cool-Temperate Zone	45° – 60° North and South	8. Western Margin Marine Climate.9.Siberian or Taiga Climate. 10. Eastern Margin or Laurentian Climate.
5. Frizid Zone (Cold Climate)	60° – 90° North and South	11. Tundra Climate. 12. Polar Climate.
6. Alpine or Mountain Zone		13. Tropical and Temperate Mountainous Climate.

 

Human Resources Geography

The Effects of Climate on Man: ”Climate Controls Lifestyle” Climate is the most determining factor of the environment. Climate, directly on indirectly affects the different human activities in his daily life. Climate determines our food, clothing, shelter, and general mode of life.

Climate and Food: Climate helps to determine our food. The food habits of the people from season to season. In cold areas, people depend on animal food to keep themselves warm. Rice is the staple food in the Monsoon climate. In hot and humid lands, people depend on vegetables and food called vegetarians.

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“WBBSE Class 8 Geography Chapter 6 notes, Climatic Regions”

Climate and Clothing: The type of clothing varies according to the changes in the weather and the climate in hot humid equatorial regions, man lives half-naked and wears cotton clothes. In cold areas, people use the right woolen clothes. In the Tundra region, People put on fur and tight-fitting clothes to Protect their bodies against cold.

Climate and Shelter: Man builds his house to suit the various elements of climate such as temperature, rainfall, etc. In areas of dense forests, man lives on the branches of trees. In polar regions, igloo houses are built by the Eskimos. In mountainous regions, sloping roofs are built to Protect against snow and heavy rain as in Kerala. Flat-roofed houses are built in hot regions while in cooler regions, glass panes are used for doors to allow more sunlight. In the Mayan region, south-facing slopes are preferred for houses.

Climate and Agriculture: Climate determines the growth of crops in a region. Three ice, in a year, are grown in Monsoon regions. In the Tundra region, agriculture is not possible due to the short growing season and vegetables are grown in glass houses.

In arid areas, irrigation is used to grow crops. Farmers and their crops are still at the mercy of climate and weather. Sugarcane, cotton, and rice are the crops suited to Tropical regions only.

Climate and Human Efficiency: Climate affects our mental alertness, physical characteristics, and racial differences. In cold areas, people are hard-working and efficient. In hot areas, people are easy-going and lazy.

Due to many fatal diseases and insects, the people in the equatorial region have poor health and the region is known as the “region of debilitation”, climate affects the growth of fungi and diseases. Agricultural Bulletins help farmers to take precautions against frost, hail, drought, etc.

Climate and Human Activities: Climate influences the location of industries Cotton textile in humid areas, fruit processing industries in the Mediterranean climate, his industry in dry areas are some of the examples.

“Class 8 WBBSE Geography Chapter 6 notes, Climatic Regions study material”

Temperate regions are densely populated due to favorable climates. Climate (direction of winds) also affects the location of the trade routes. Modern air transport, military operation, and geographical expeditions depend on meteorological reports.

Thus, it can be concluded that climate has both direct and indirect influences on human activities, civilization, and mode of life. It is one of the fundamental components of nature and the environment. Man has learned to adjust and adapt himself to the varying climatic conditions.

Chapter 6 Climate Regions: Hot-Humid Equatorial Climatic Region

The Equatorial Regions are known by several names depending on the types of climate or local natural vegetation. The regions are described as ‘Hot-Humid/Wet Equatorial Region’, “Equatorial Rainforest Region’ or “Tropical Rain Forest Region’.

The region experiencing a hot, wet equatorial climate has high temperatures and much rainfall throughout the year. So dense forests grow here. The region is hence called the ‘Equatorial/Tropical Rainforest Region’.

The uniqueness of the Equatorial Region: The Equatorial Regions have several distinctions to their credit—

1. They are the lands of the overheating sun.
2. They receive very high insolation.
3. The difference between the durations of day and night is the least.
4. The periods of dawn and dusk in the region are the shortest.
5. They are the lands with the highest relative humidity all through the year.
6. They have only one season—simultaneously hot and humid.
7. With ascending air it is a region of calm or doldrums. Thus the Equatorial Regions are unique in themselves in ways more than one.

Location: The Equatorial Region extends generally between 10″ North and 10″ South latitudes on both sides of the Equator. The region includes parts of the Amazon Basin and Guianas in South America. Zaire Basinand Guinea coastjn Africa.

In Asia, the main areas are Malaysia Indonesia, Papua and New Guinea, Southern Philippines, and peninsular parts of Thailand.

Chapter 6 Class 8 Geography

The characteristics of Equatorial Climate: High temperature, heavy rainfall, and perpetual summer without any change of seasons characterize the equatorial type of climate. They can be summed up in the following:

1. The Equatorial Region receives vertical rays of the sun all year round and therefore temperature remains high.
2. Throughout the year temperature remains almost the same.
3. The average temperature all around the year ranges between 25°C to 27°C.
4. The range of temperature between day and night is minimum [2° to 5°C].
5. There is no change of season.
6. Rains fall all year round. It occurs in heavy downpours.
7. The annual rainfall averages between 200 cm to 300 cm.
8. There is no dry month. Generally, rainfall occurs every day. It comes at a particular hour.

Conditions of the important elements of climate in the Equatorial Region:

Temperature: Temperature conditions range between 25°C and 30°C during the year. The annual range of temperature is usually less than 5°C. If the maximum temperature during the day is about 30°C, the minimum temperature at night may be about 25°C.

Cloudy skies Prevent the loss of radiation in the night and cooling of the atmosphere. The difference between maximum and minimum temperature among the different months of the year is so small.

Air pressure and wind: Intense low-pressure forms over the Equatorial Region due to high temperatures throughout the year.

“WBBSE Class 8 Geography Chapter 6, Climatic Regions study guide”

The location of this type of climate coincides with that of the Equatorial low-pressure belt and the ‘Inter Tropical Convergence Zone’ (ITCZ). NE and SE trade merge here. Equatorial calm/Doldrums has formed here.

Place Kualalumpur	J	F	M	A	M	J	J	A	S	O	N	D
Temp, in °C	26.1	26.1	26.6	26.6	26.6	26.6	26.1	26.1	26.1	26.1	25.5	26.6
Rainfall in cm.	16.7	16.7	23.2	27.5	12.5	10.2	15.5	13.2	27	25	25	22.7

 

Rainfall: Convection rainfall occurs throughout the year. The sky is generally clear in the morning, but rainfall occurs in the afternoon between 2 pm to 4 pm. with thunders in torrential form. So, this rainfall is known as ‘4 o’clock rain’. The sky clears up again at night.

Chapter 6 Climate Regions: Biodiversity

Flora/Natural Vegetation: Due to high temperature, humidity, and rainfall, the flora or natural vegetation of Equatorial Regions is very luxuriant. Tropical or Equatorial rainforests are found in this region. There are four levels of vegetation found in Equatorial forests.

1. Some of the trees manage to grow as tall as 40 to 45 meters (above 30 meters). These are Emergent trees.
2. The next in order are the trees with medium heights (about 15—30 meters). There is a continuous layer of tree crowns.
3. Palms and Palmyra trees open up their crowns at a lower height (In between 7-5 to 15 meters). There were young trees festooned with lianas.
4. The ground floor of the layered or multi-storeyed forest consists of the regrowth of ferns and short bushes. The fern-like undergrowth is not dependent on sunshine. Creepers climb up the trees weaving a maze as it were.

Over a small area un reds of different species of trees grow side by side. The trees are so close to each other at their leaves form an overhead layer or canopy. The canopy does not allow sunlight to penetrate and reach the forest floor.

So, this region is known as the “Region of twilight”. The equatorial forests are known for hardwoods. The main trees of these forests are mahogany, rubber, guttapercha, cinchona, sandal wood, rosewood, ironwood, cocoa, palm, oil palm, sago palm, coconut palm, etc. Sal, Teak, and Ablus trees are also found here.

“WBBSE Class 8 Climatic Regions notes, Geography Chapter 6”

Summing up all the features we can conclude the following chief characteristics of these forests.

1. The thickest vegetation is found around the Equator. Great heat, abundant rainfall, and bright sunshine are basic factors responsible for thick forest growth.
2.  Mahogany, ebony rosewood, ironwood, rubber, etc. are found in abundance. These trees are hardwood trees.
3. There are great varieties of trees found scattered throughout the whole forest area.
4. In marshy lands and river mouths, such as in the Guinea coast, coconut, and palm oil trees are found in abundance.
5. There are distinct layers of arrangements in equatorial forests.

Fauna/ Animal Life: The Equatorial forests abound in wildlife. There are varieties of wild animals. They can be categorized as follows:

Giant Animals: These types of animals are found in two places. Elephants and Rhinoceroses are found near the edges of open forests where some grasses are also available. Hippopotamus is found in lakes, rivers, and swampy areas. Hippos, crocodiles, turtles, and different kinds of fish are also found in swamps and lakes.

 

 

Birds and Anlrpfs pertaining to Trees: These types of animals include monkeys, bats, flying squirrels, tree frogs, tree lizards, tree iguanas, and reptiles. Flesh-eating animals such as snakes and jaguars are also found on trees. Most of these animals live on trees due to marshes.

 Insects: In this group of wildlife are included butterflies, termites, spiders, ticks, gnats, mosquitoes, ferocious diver ants, etc.

Chapter 6 Climate Regions: Socio-Economic Environment and Lifestyle

Inhabitants and their lifestyle: In hot and humid climates(Equatorial/Tropical Rain forests) the lifestyle of the indigenous peoples is largely controlled by physical environments. The Pygmies of the Congo (Zairge) basin, Red Indians of the upper Amazon basin, and Semangs of south-east Asia (Malaysia) are the main inhabitants of this region.

They are food-gathering and hunting tribes. The Andamanese and Negrito people ore still in the hunting and food gathering stage because of their oppressive and harsh climatic conditions.

“Class 8 WBBSE Geography Chapter 6, Climatic Regions easy explanation”

The Pygmy: The Pygmies of Congo (Zaire) basin in Africa are primitive people and are one of the most backward tribes in the world; they belong to Mobutiar,d Banbuti tribes. They live in the thickest part of the equatorial forest of the Congo (Zaire) basin since time immemorial. They live in small bands and live on hunting and gathering of fruits and roots of the forest.

 

Their mode of life is in perfect harmony with the environment. As the Pygmies roam after games and gather fruits and roots of the forest from one place to another, they have no permanent shelter. They wear little clothes. Their clothes consist of barks or leaves of trees. They also use the skin of animals. The pygmies still lead their Primitive life.

“WBBSE Class 8 Geography Chapter 6 notes, Climatic Regions PDF”

The Red Indians of the Amazon basin: The Red Indians of the Amazon basin are some of the backward tribes of the world. They live in the selva forest of the Amazon river basin of South America.

They are widely scattered over the forest, but they have a similar ways of living. They live on hunting and gathering fruits and roots of the forest. They wear very little clothing and eat all kinds of animals. Little change is found in them.

 

Semang: Semangs are indigenous peoples of the Malay Peninsula in Southeast Asia. They are of small stature with wide noses, thick lips, and a black complexion. Like their food supply, the clothing of the Semang is supplied mainly from the forest.

They do not build permanent dwellings and live in temporary huts. The mode of living of the Semang is in the hunting stage.

In recent years, some changes have been noticed in their lifestyle. Some of them have come to contact of modern civilization. They flock to the rubber gardens to secure jobs. They are willing to work and join the general flow of living in the modern world.

Other Primitive Tribes of S.E. Asia: There are a number of primitive tribes in eastern Malaysia. Of them Iban, Dasunand Torajaare important. The Andamanese, Jarov/as, Onges, Sentineleesof the Andaman Group of Islands, live on hunting and gathering fruits and roots of the forest.

They still follow their primitive ideas and lead the life of the jungle. Nicoborees and Shompen live in the Nicobar group of Islands. They also live wildlife.

The Equatorial regions are generally the most backward areas of the world. An unhealthy climate and diseases like yellow fever make people lazy. They have poor health and lack energy. Hence, it is called a region of debilitation’.The oppressive climate makes it unsuitable for white settlers. This region is thus called the “white man’s graveyard”.

Occupations of the people:

Hunting: The native people hunt animals, birds, and reptiles with poisoned arrows.

Fishing: People living near rivers and sea, are fishermen. They use a boat named a canoe for fishing.

Limbering: Lumbering is limited. Some valuable hardwood trees are cut for cabinet wood.

Mining: ln some areas, mineral resources are exploited, such as copper in Zaire Basin, tin in Malaysia, petroleum in Indonesia, and gold, bauxite, and manganese in Ghana.

Food gathering: The native people collect many materials from the forests such as fruits, ivory, nuts, rubber, gum, drugs, etc. Quinine is obtained from the Cinchona tree in java.

Shifting cultivation: Some native tribes practiced a special type of agriculture. It is known as sffittmg cultivation, ‘Milpa'(Brazil), and ‘Ladang'(Indonesia). Forests are burnt and cleared. Crops of rice, millet, manioc, and bananas are grown. After two or three crops, the fertility of the soil is exhausted and people move on to new plots of land.

 

Plantation Agriculture: European traders established colonies here in the eighteenth and nineteenth centuries and practiced plantation farming in these regions,

1. Rubber in Malay, Java, and Sumatra of south-east Asia,
2. Sugarcane and banana in West indies,
3. Cocoa and plam on the Guinea coast,
4. Tea and coffee in Sri Lanka,
5. Spices and coconuts in Sri Lanka were the main plantation crops that provided a livelihood for local inhabitants.

Industry: The dearth of raw materials has prevented the growth of heavy industries in this region. However, some industries have emerged based on local agro-based, forest based and mineral-based raw materials.

 

Present Scenario: In this region, the environment is unfavorable for human settlement. In recent years uncontrolled growth of the population has led to the emergence of new settlement here.

Vast stretches of evergreen rainforest is being destroyed every day due to the great demand of land for settlements, cultivation, industry, and transport.
Civilization is at a low level in most areas.

Where white men have settled, people have a better mode of living. Lumbering has become an important industry. Sawmilling has also developed. In some parts, margarine, and soap making, sugar-producing, and palm oil extracting are notable.

“WBBSE Class 8 Geography Chapter 6, Climatic Regions important questions”

Future Prospects: Even today, the equatorial region does not show much sign of advancement. With the progress of science and technology, there is a great possibility for the development of the equatorial region:

1. Today’s backward regions hold possibilities for the generation of hydroelectric power, which can bring about economic progress.
2. Application of atomic energy may help eradicate of various diseases and thereby will pave the way for human habitation.
3. Forest clearings will provide ample scope for agricultural practices. The native tribes will come to contact with the civilized people and they all together will build up a new home for a man with modern amenities of life.

Chapter 6 Climate Regions: Warm Climate -Monsoon Climatic Region

The word ‘Monsoon’ is derived from the Arabian word ‘Mousim’ or the Malayan word ‘Mausin’ both of which mean ‘season’. So, the wind that blows following the season is known as ‘Monsoon Wind’, and the climate controlled by that wind is called ‘Monsoon Climate’.

Location: The Tropical Monsoon type of climate occurs in the eastern margins of continents lying 10° to 30° north and south of the Equator. The climate of the south and south-east Asian countries, namely India, Pakistan, Bangladesh,- Myanmar, Thailand, Laos, and Vietnam are monsoon types.

The Phillippines, South China, Queensland of northern Australia, east coast of Africa such as Somalia, Madagascar, Mozambique, Florida coast of U.S.A., east coast of Brazil are also affected by this type of climate.

Climatic Characteristics: The Tropical Monsoon climate is characterized by the following factors:

This type of climate is mainly controlled by the ‘Monsoon wind’.

The climate is influenced by the ‘Tropic of Cancer (23 1/2° North) and the ‘Tropic of Capricorn (23 1/2° South).

The wind blows in opposite direction in summer and winter. In monsoon lands in summer moist south-west monsoon wind blows and in winter dry north-east monsoon wind blows.

1. The region is also characterized by hot-humid summer and dry mild winter.
2. Average summer temperature varies between 30°C and 32°C and in winter, average temperature ranges between 19°C and 22°C.
3. Annual rainfall of monsoon lands varies between 125 cm and 175 cm. But rainfall decreases away from the coasts to the interior.
4. The amount of total rainfall is lesser than in the equatorial region. Rainfall occurs mainly in the summer. Winters are generally dry.
5. Seasonality is a salient feature of the monsoon climate. ,
6. In the Northern and Southern hemispheres seasonal conditions are just reversed.
7. The whimsical nature of monsoon ‘Gambling of the monsoons’ causes floods and droughts.

Geography Human Resources Class 8

Seasonal Characteristics of the elements of climate in the Monsoon climatic Region: The monsoon climates are basically caused by the unequal heating or cooling of the land and sea.

This results in differences of pressure. So, winds blow from high-pressure to low-pressure areas as the on-shore wet monsoons in summer and off-shore dry monsoons in winter. The principal characteristic 60 of monsoon climate is a charge of seasons.

In Northern Hemisphere:

1. From December to February, it is cold 48 and dry winter. The average temperature is generally 19°C—22°C. South-east trade wind blows over South and Southeast Asia as the North-east monsoon wind. This wind does not cause rain to fall.
2. From March to 24 May, it is a hot and dry summer. The average temperature is about 3 0° C. Sometimes temperature exceeds 38°C. Intense heat creates low pressure over the landmass. Some amount of rainfall occurs in Assam, Bangladesh, and Myanmar in the months of March and April.
3. From June to September, it is the rainy season. When the South-west monsoon comes from the Indian Ocean via the Arabian sea branch and the Bay of Bengal branch enters the Indian Sub-continent then sudden and heavy rainfall occurs with thunder and lightning. It is known as the ‘Burst of Monsoons’. In this season water vapor is maximum in the air an occurs in November Then temperature is decreased due to rainfall.
4. From the middle of September, it is Autumn, which is also known as the season of ‘Retreating Monsoon, energy, and cold climate prevail. The formation of a deep depression in the Bay of Benga causes thunderstorms.

Month	J	F	M	A	M	J	J	A	S	O	N	D	Yearly average Temp./Rainfall
Temperature (c)	25	26	29	31	29	27	27	27	27	28	27	25	27
Rainfall (cm)	0.5	0.5	0.8	40	30.5	45.7	54.4	50.5	38.9	17.5	7.1	10	251.4

 

Chapter 6 Climate Regions: Biodiversity

Flora/Natural Vegetation: The vegetation of the monsoon region varies with rainfall, is more than 200 cm, Tropical Evergreen Rainforests are found. These forests are more open than the Equatorial Rain Forests (Selvas) and there are fewer species. Ebony Mahogany, Rosewood, Toon, Poon, and Chaplash are some trees of these forests.

Where rainfall is less and there is a marked dry period, deciduous forests of Sal, Mahua, Palash, Teak, Bamboos, Acacia (in drier areas), and varieties of Eucalyptus (in northern Australia) are found. In areas of scanty rain, semi-arid desert conditions prevail.

“Class 8 Geography Climatic Regions notes, WBBSE syllabus”

There the vegetation consists of Cacti and Thorny bushes. Fruit trees like Mango, Jackfruit, and Bananas are also common in India and Bangladesh. In the Sundarbans mangrove forests (Sundari, Garan, Geona, Hental, etc.) are found.

Fauna/Wild Life: Important wild animals of monsoon lands are elephants, Rhinoceros, monkeys, Deer; Jackals, Hyenas, leopards, wolves, bears, foxes, etc. The Sundarbans of India and Bangladesh is the home of the famous ‘Royal Bengal Tiger’  and Gir forest in Gujrat is the home of Lions.

Different types of reptiles like snakes’ are found in this region. At the river estuary of coastal areas crocodiles, Turtles, Crabs, and huge amounts of Fish are found.

Agriculture: Agriculture is the chief occupation and forms the backbone of the economy of this region. But in this regard, the role of monsoons is very vital. A variety of crops, such as rice, wheat, millets, oilseeds, Jute, Tea, Coffee, and different vegetables are cultivated in monsoon lands. Among these crops, rice is the most important.

 

 

 

Pastoral Resource: Livestock farming is practiced in this region as a subsidiary occupation on a domestic level. These animals are cattle, buffaloes, and sheep. Therefore, large quantities of milk, meat or hides or skins are produced.

Mineral Resources: Certain areas in monsoon lands are rich in mineral resources. Coal, bauxite, mica, manganese, copper, and iron ore is available abundantly in peninsular India. Petroleum and Natural gas are produced in Myanmar, Southern China, and in some parts of India.

Besides these minerals, Thailand produces tin, Myanmar produces tungsten and precious stones and Bangladesh produces natural gas.

Industry: Industries are developed in those areas where agricultural and mineral resourceslafe available. The important industries of this region are—

1. Iron and steel industry Cotton and Jute textile, sugar, and engineering industries in India,
2. Jute industry in Bangladesh,
3. Oil refining in Myanmar,
4. Electronics and engineering industries in Thailand,
5. Sugar, cotton, and jute industries in Sn China,
6. Cotton textile industry in Pakistan.

“WBBSE Class 8 Chapter 6 Geography, Climatic Regions solutions”

Transportation: Innumerable roadways and railways run through the plains of monsoon lands. Rivers provide cheap waterways. Most of the important and big cities and towns are connected by airways. All the modes have been well developed. But the transport system of the monsoon climatic region in Africa and South America is not developed.

Settlement: Monsoon regions of Asia is the world’s most densely populated area. Due to favorable fertile soil, enriched agriculture, and developed transport network density of the population is very high in the river valleys of the Ganges, Indus, Brahmaputra, Irrawady, Si-kiang, Mekong, etc.

But in the mountainous regions and scanty rainfall areas of monsoon regions are sparsely populated. The density of the population is also very less in the coastal areas of Brazil, northern Australia, and in the eastern coast of Africa.

The lifestyle of the people: The Monsoon climatic region is the best-suited region for human settlements. Monsoon lands have a long history of human occupation. India and China are among the oldest civilizations in the world.

There is a rich diversity of religion, culture, r costumes, and social customs. Monsoon region has an agricultural civilization. Most of the people live in villages. People have a low standard of living. Some of the largest towns in the world are found in this region.

Cities and ports: The important and major populated cities are—

1. Mumbai,
2. Kolkata,
3. Delhi (capital),
4. Chennai,
5. Bangalore,
6. Hyderabad in India
7. Karachi in Pakistan,
8. Dhaka (capital) in Bangladesh,
9. Colombo in Sri Lanka,
10. Yangon in Myanmar,
11. Bangkok (capital) in Thailand and
12. Hanoi (capital) in Vietnam.

Important ports of the Monsoon lands are Mumbai, Chennai, Kolkata, Yangon, Karachi, Chittagong, etc.

Future of the region: There is a bright possibility of rapid economic prosperity in this region through developed infrastructure, technology, and establishment -of modern industry with the abundance of favorable climate, agriculture, forest products, and mineral resources. Though there are different problems, this region is developing gradually. So, this region is called, the “Region of Increment”.

Chapter 6 Climate Regions: Temperate Climate- MediterraneanClimate Region

The Mediterranean climatic region is a special region of a warm temperate zone. The Mediterranean type of climate gets its name because extensive areas abound the Mediterranean sea enjoy this climate. In general, the western margins of the continents in the warm temperate zone have Mediterranean climate.

Location: The western portion of the continents lies between 30 to 45 North and South of the Equator. France, Italy, Greece, Spain, Portugal, Albania, Former Yugoslavia of Europe, Turkey, Israel, Syria, Lebanon of Asia, Egypt, Morocco, Libya, and Algeria.

“WBBSE Geography Class 8 Climatic Regions, Chapter 6 key concepts”

Tunisia of Africa—these sixteen countries are mostly influenced by the Mediterranean climate. There are some areas that are not abounded by the Mediterranean sea but there this type of climate can be observed.

These areas are as follows:

1. The coastal areas of California in North America,
2. Central Chile, 3Q west of the Andes range in South America. It is 28 the most representative form of the Mediterranean 26 type climate.
3. Cape Town in South Africa.
4. South-east and 20 South-western parts of Australia and Northern 18 Island of New Zealand.

Month	J	F	M	A	M	J	J	A	S	O	N	D	Yearly average Temp./Rainfall
Temperature (c)	12	13	14	16	17	18	21	22	21	18	16	13	17
Rainfall (cm)	8.1	8.4	6.6	2.5	1	0.3	0	0	0.5	1.3	2.8	6.1	376

 

Climatic Characteristics: The chief characteristics of the 12 Mediterranean climates are as follows:

1. Moderate temperature prevails throughout the year.
2. Rainfall occurs in winter but summer remains dry (reverse of monsoon climate).
3. This climate is D 1 influenced by the location of seas.
4. During the dry summer, the Mediterranean regions are under the influence of trade winds. During the winter season, this region comes under the influence of the westerlies.
5. The total amount of rainfall in this region is about 50 cm. to 100 cm. annually.
6. The Mediterranean climate is characterized by bright, sunny weather. Sunshine is always abundant in the Mediterranean lands because the sky is clear almost throughout the year.
7. The temperature drops sharply at night because of the clear sky.
8. The range of temperature is higher than equatorial climate but less than Tropical Monsoon or Tropical desert type of climate.

Seasonal conditions of the elements of climate in the Mediterranean Climatic Region: In winter the prevailing on-shore westerlies bring much rain from the ocean to the Mediterranean lands. Winter is the rainy season in the Mediterranean lands where annual rainfall varies between 30 cm. and 90 cm. The average winter temperature ranges between 5°C and 10°C.

In summer with the shifting of the westerlies poleward, the Mediterranean lands come under the Trade winds. The prevailing Trade winds are off-shore; as such they are dry and give no rain. The average summer temperature of this region varies between 21°C and 27°C. The range of temperature is about 6°C to 8°C.

Place: Upernavik	J	F	M	A	M	J	J	A	S	O	N	D
Temp. in C	-22.2	-22.2	-21	-3.8	-1.6	5	5	1.1	1.1	-3.8	-10.01	-17.2
Rainfall in cm.	1	1.2	1.7	1.7 1	1.5	1.2	2.2	2.7	2.7	2.7	2.7	1.2

Chapter 6 Climate Regions: Biodiversity

Flora/Natural vegetation: Winter rain and summer drought control the growth of natural vegetation here.
(1)In certain cooler highlands, Evergreen Coniferous trees, such as pine, fir, spruce, larch, cedar, palm, etc. are found.

(2)Evergreen broad-leaved trees are found on low-lying areas. The chief characteristics of this type are as follows:

1. The leaves of some plants are leathery. They have capacity to restore water,
2. The roots are long, thick, and wide spreading. They draw moisture from deep layers of the earth,
3. The barks of some plants are thick and have a narrow opening where they can store water. Cork oak, Olive, Chestnut, etc. are the chief trees. Olive trees are seen in maximum in this region.

(3) The shrubs and bushes are also growing: Typical Vegetation of Mediterranean Lands. ‘ on the hillsides. Rose Mary, Laurel, Mallee, Maquis, Lavender, etc. are the main varieties.

Fauna/Animal life and rearing: Due to rainless dry summer and wet winter here is found little grassland and the lack of lush Greenlands makes this region unsuitable for animal rearing.

Hence donkeys, sheep, goats, and mules are more reared than horses or cattle. Hen and camel are more reared near hot deserts. Sheep rearing is important in Spain. The original home of the merino sheep is prized for wool.

“WBBSE Class 8 Geography Chapter 6, Climatic Regions summary”

Agriculture: Agriculture is the main economic activity of the people in most parts of the Mediterranean lands. Temperate climates and moderate rainfall enrich this region in agriculture. Important agricultural crops are cereals like wheat, maize, barley, and rice; vegetables like tomato, beans, carrot, etc. and fiber crops like hemp and cotton.

Due to moderate rainfall, and bright and abundant sunny weather in this region grapes, oranges, olives, apples, apricots, peaches, almonds, pears, lemons, walnut, peanuts, plum, and different types of citrus fruits are produced here.

 

Hence this region is known as the “Basket of fruits” or ” Orchard Farming Lands” of the world. The typically Mediterranean fruit is olive which is used not only as a cooling medium but also used for making olive oil and cosmetic industry.

MineraljResource: This climatic region is not rich in minerals. A few minerals are produced in limited areas, such as iron ore is produced in Spain; Sulpher, mercury, marbles, and granites are available in Italy; Bauxites is mined in southern France; petroleum, natural gas, and gold are produced in California; chromium, lead, and zinc in Turkey and nitrate is produced in central Chile.

Industry: Many countries of the Mediterranean climatic regions are famous for different industries. The major/ important industries are

1. Fruit processing industry (Jam, Jelly, Pickle, etc.)
2. Wine Production,
3. Tourism developed due to bright sunshine, moderate climate, and attractive scenic beauty and
4. The film industry of Rome in Italy and Hollywood in California where the clear sky and long hours of bright sunshine are very much favorable for this industry. Other industries
5. include,
6. Engineering,
7. Petrochemical,
8. Aluminium and
9. Flour industry.

Settlement and Lifestyle of the People: The charming healthy climate of this region is suitable for human settlement. Developed economic infrastructure, the privilege of occupation make this region densely populated and inhabitants are economically enriched.

The Mediterranean shorelands were the ‘cradle of world civilizations’ in the past. These regions were seats of ancient civilizations like Greek, Roman, etc. This region gave birth to great religions of the world. People are highly civilized.

Important Cities and Ports: Important cities of the Mediterranean climatic regions are—Rome (capital of Italy), and Naples in Italy. Athens (capital) in Greece; Cairo (capital) and Alexandria in Egypt, Til Aviv (capital) in Israel; Algiers (capital) in Algeria; Los Angeles in California; Adelaide in Australia; Cape town in South Africa; Llsben in Portugal are the main cities, ports, and industrial centers.

Future of the Region: Mediterranean lands were once the cradle of the civilization of Romans and Greek. For human development, climate plays an important role. It also attracts a large number of tourists.

“WBBSE Class 8 Geography Chapter 6 Climatic Regions, definitions and examples”

Scientific and economic development have helped people achieve a high standard of living. All the countries of this region are highly developed and densely populated. People can easily earn their livelihood with a little effort. Therefore, the Mediterranean region is also called the “Region of Increment”.

Chapter 6 Climate Regions: Cold Climate-Tundra Climate Region

A cold barren plain region lying around the Arctic circle is called the ‘Tundra pimatic Region’. Northern parts of Asia, Europe, and North America are ice-capped and have typical vegetation like algae, such as mosses and lichens which grow only in a few ice-free months.

‘Tundra’ is the name of this type of vegetation, as such the climate is named after its vegetation.

Location: This region is lying beyond 65° north parallel of latitude and on the northern side of the coniferous forest belt. On the map, this location is marked by Isotherm limits of 0° to 10°C. Beyond it there is perpetual snow.

Boundary: The Tundra Climatic region covers the coastal strips of the Arctic Ocean in North America, Europe, and Asia. The main areas are the coastal strips of Canada and the coastal strip of Greenland. In Europe, the Tundra covers Iceland, the northern coast of Scandinavia, and small islands adjoining the coast.

The arctic coast of the Russian Commonwealth has a narrow strip of Tundra. A small part of Antarctica in the southern hemisphere is also in this region.

Characteristics of the climate: The climate of the Tundra region is characterized by the following feature:

1. It experiences severe cold and long winters.
2. Summer are short and cold.
3. Winter temperature remains below the freezing point (average temperature-22)
4. Temperatures are very low all year round.
5. The range of temperature between the maximum and the minimum is very much wide.
6. The rainfall is scanty and it is less than about 25 cm. annually.
7. The rainfall is chiefly of cyclonic in origin and falls in the summer
8. Heavy snowfall and blizzards are common in Winter.

Seasonal Conditions of the major elements of the climate:

Winters are very long in this region. For about nine to ten months temperatures remain at freezing point. When heavy snowfall and blizzards occur, then the ground becomes frozen. The temperature drops to even from – 30°C to – 40°C. In winter, there is continuous darkness for 2/3 months.

“WBBSE Class 8 Geography Climatic Regions, revision notes”

However twilight stays for long periods when snow reflects the light of different celestial bodies and the glowing red or green curtains of Aurora Borealis are visible in the six months night sky. Summers occur here only for 2/3 months when temperature varies between 0°C and 10°C. The rainfall is light and occurs in Summer.

Chapter 6 Climate Regions: Biodiversity

Flora/Natural Vegetation: The natural vegetation of the Tundra region can be divided into the following groups

1. The Bush Tundra,
2. The Grass Tundra and
3. Flowering vegetation.

 

1. The Bush Tundra: The Bush Tundra has scrubby alders, birches, and willow which grow during short summer when ice melts.
2. The Grass’Tundra: The Grass Tundra covers a large area and grows generally under thick snow cover. Moss, lichen, and sedge are these types of vegetation.
3. Flowering Vegetation: During the summer, the thick ice cover begins to melt down and the flowering plants start to grow. They are short-lived plants and die after showing their colorful sight for a short period.

Fauna/Animal Life: In the Tundra climatic region most of the land animals are equipped with thick furs or long hairs to protect themselves against the bitterly cold winters. They have also thick layers of fat which provide them with more protection and food reserves for winter.

They are reindeer, polar bear, blue fox, musk-ox, hare, sled dog, caribou, and lemming. In the coastal region of the Arctic seas, there live seals, walruses, whales, and different types of fish. In summer birds migrate to the north and inhabit the Tundra. Penguins are very common in Antarctica.

Chapter 6 Climate Regions: Socio-Economic Environment And Life Style

Inhabitant’s lifestyle: The region is the least developed. The population is sparse. The average density of the population is less than one person per square kilometer. In North America, the number of Eskimos is only about 25000. Agriculture is not possible.

Life is difficult as the means of livelihood are limited. Therefore, this region is called the ”Region of Everlasting Difficulties”.

Occupation of the people:

1. Hunting: Most natives are hunters. They depend on hunting for fur and food.
2. Fishing: In coastal areas, people are fishermen. Eskimos use a boat named ‘a kayak’ for fishing. A spear named ‘harpoon’ is used for hunting seals.
3. Trapping: Trapping for fur-bearing animals is an important occupation.
4. Herding: Fur-bearing animals are reared on a commercial scale. Reindeer Farms have been established in Siberia.

 

The Lifestyle of the People: People in the Tundra are Nomads. They have to adapt themselves to the harsh environment. Many nomadic tribes are found in different parts of this region such as:

1. The Samoyeds, Yakuts in Siberia,
2. Laps and Fins in Europe,
3. Eskimos in Canada and Alaska.

“WBBSE Class 8 Climatic Regions notes, Chapter 6 worksheet”

These tribes move from place to place in search of food’ They can hardly maintain a livelihood. So, their number is decreasing. They live in compact snow huts (Igloos) during winter. In summer, they live in portable tents of skin (Topics).

Eskimos are hunters, fishers, and food gatherers. Their food is obtained from berries, fish, seals, and walruses. Reindeer provide a supply of meat, milk, fat, etc. Warm clothes are used in this region.

Recent Developments in Tundra Region: During the last few decades, the lifestyle of the Eskimos has seen many changes due to contact with white men. Log cabins, wooden houses, speed boats, and guns are being used. Women use sewing machines instead of bone needles. Reindeer farms and fisheries have been developed.

“Class 8 WBBSE Geography Chapter 6 Climatic Regions, multiple-choice questions”

Railway lines have been constructed for transporting minerals. Ports like Igarka have been constructed on the Arctic ocean. Fur and Timber is shipped from Siberia. Modern ‘Ice-breakers’ keep the ports free. Many meteorological observatories have been established for the study of weather conditions.

Air transport is increasing in polar areas. Some parts are made ice-free and agriculture is done here with the latest technology by the greenhouse. Recently this region has been developed and inhabitants are habituated to modern lifestyle.

Future of this region: The region, was once regarded as completely useless, but now there is an indication of economic improvement that will be of great.

WBBSE Notes For 8 Class Middle School Geography

zChapter 7 Human Activities And Environmental Degradation

Even in the modern computer world environment plays a great role in human life. The word ‘environment refers to all those visible or invisible elements around a man which directly or indirectly affect his life and livelihood.

The advancement of Civilization and its effect on the environment:

Early man was not capable of modifying his environment. He could not cut the trees even. He was frightened by the lightning and thunder of the clouds. He was afraid of wildlife living in dense forests.

Read and Learn all WBBSE Notes For 8 Class Middle School Geography

He was threatened by vast oceans and rivers. He used to worship the different forms of nature such as mountains, oceans, rivers and forests. It is an evidence that man was dominated by nature.

In early times, the lifestyle of man was entirely dependent on nature. Then his demands were few and all his time was devoted to gathering food, hunting and self-defence. Gradually, a man tried to live in harmony with nature—

1. He started felling the trees and using the wood for his shelter,
2. He learnt how to lit light and fire. Fire protected him from wild animals and cold,
3. He started hunting wild animals,
4. He made tools out of stone and then metals,
5. Hunting and fishing helped him to overcome nature,
6. The use of technology helped man to overcome the limitation of the environment,
7. Agriculture provided a settled life of man.
8. Transport helped him to discover new areas,
9. Man modified his environment with new inventions,
10. The desert climate of Saudi Arabia was modified by the use of Air-conditioners.

Human activities has resulted in the degradation of the environment in the past. They were not aware of it. Deforestation has led to declining of Mesopotamian civilization in Iraq, Incas in Peru, and Indus valley civilization suffered due to the felling of trees on hill slopes. It resulted in soil erosion, floods, silting of canals and making cultivated land barren. It resulted in famines, droughts, deaths and desertion of villages.

Class 8 General Science	Class 8 Maths
Class 8 History	Class 8 Science LAQs
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“WBBSE Class 8 Geography Chapter 7 notes, Human Activities and Environmental Degradation”

The Industrial Revolution in the eighteenth century was a giant step in the advancement of civilization. From that time onward progress in industry, science, medicine and technology was really expedited.

The Industrial Revolution encouraged the use of machines. Steam engines and other machines were invented. It had a dangerous effect on the environment.

1. It disturbed the equilibrium of the environment.
2. Many people died of accidents in factories.
3. Smoke from the factories and many pollutants polluted the water and air.
4. The population has increased. It has led to an energy crisis also.

The two World Wars in the twentieth century, testing of military weapons, scientific research and experiments and economic development started changing the face of the planet irreversibly. The malice of these has affected the entire living world adversely.

Chapter 7 Human Activities And Environmental Degradation: Environment Degradation

Environmental degradation is the deterioration of the quality of the environment. Elements of the environment like water, soil, air etc. are affected by such deterioration.

“Class 8 WBBSE Geography Chapter 7 notes, Human Activities and Environment study material”

Environmental degradation refers to the deterioration in the physical components of the environment, mainly due to the biological processes but more especially human activity, to such a great extent that cannot be easily restored by the self-regulatory mechanism or homoeostatic mechanism of the environment.

Human Activities That Affect The Environment

 

 

 

 

 

 

 

 

 

 

Homoeostatic Mechanism: The physical and biotic processes of nature have a self-regulatory style of working. Any change or damage caused by them to the environment is naturally restored, compensated or adjusted. This is called Homoeostatic Mechanism.

Environmental degradation may be due to extreme events and hazards or pollution. Extreme events and hazards are unexpected threats of a large impact. They may be classified on the basis of causative factors.

Natural Hazards: Natural Hazards are caused by natural factors. These may be terrestrial natural hazards which occur on the earth’s land surface, e.g., the continents and are caused by endogenetic forces, e.g., volcanic eruptions, earthquakes etc.

“WBBSE Class 8 Geography Chapter 7, Human Activities and Environmental Degradation study guide”

Atmospheric natural hazards occur by atmospheric processes affecting the living (biotic) and nonliving (abiotic) components of the natural environmental system, e.g., cyclones, forest fires etc. and cumulative atmospheric hazards, caused by atmospheric processes which accumulate for several years in continuation, e.g., flood, drought etc.

Man-made Hazards:

Man-made or Man-induced hazards are the result of cumulative and even sudden effects of man’s activities. These could be physical man-induced hazards, caused by large-scale landslides, deliberate forest fires etc;

chemical and nuclear hazards, caused by the release of toxic elements in the atmosphere by human activities, accidental outbursts of poisonous gases from chemical factories, nuclear explosions; and biological hazards induced by man, for example, sudden increase or decrease in the population of a species in a region due to increased nutrients or increase in toxic elements.

Biological hazards (not caused by man) include dangers posed by epidemics, natural extinction of any particular species, locusts, swarms etc.
It should be noted that environmental degradation caused by natural factors affects human lives but nature and mankind can restrict and repair such damage to a great extent.

On the other hand, various human activities (transportation, industrialization, use of chemical fertilizers and technology, and overall development) have irreversible adverse effects on the environment.

Chapter 7 Human Activities And Environmental Degradation: Some Development Plans And Their Effects

Modern Agricultural Methods:

Aim: The aim of the modern agricultural method is to increase agricultural production.

Results: Different chemical fertilizers and pesticides are used to increase agricultural production but it has an irreversible adverse effect on the environment. It pollutes soil and water.

Polluted water flows into the soil, is discharged into ponds, canals, rivers and other water bodies killing aquatic flora and fauna. Unscientific methods of cultivation reduce soil fertility also.

Urbanisation:

Aim: The aim of urbanisation is the provision for shelter and a better lifestyle.

Results of Urbanisation:

Urbanisation depletes the reserve of underground water. It creates air and noise pollution. It creates problems of water logging. Many big cities of developing countries or the third world have grown around unplanned old cities. As a result, drainage and sanitation problems, traffic congestions and shortage of housing are acute.

Power Plants:

Aim: The aim of power plants is to produce electricity.

Results:

The burning of coal and oil adds carbon dioxide and sulphur dioxide to the atmosphere. The nuclear power plant also emits poisonous wastes to the environment, Due to the pollution and increase of atmospheric temperature the balance between heat received and radiated by the earth is disrupted.

Ash and wastes from power plants are dumped in nearby areas, thereby decreasing the fertility oi land as well as polluting the waters of rivers. Such as the Kolaghat thermal power station of Medinipur, West Bengal polluted air and its deposited ashes decreasing the fertility of the nearly agricultural lands as well as polluting the water of the river Rupnarayan.

 

Human Environment Modification

Multipurpose River Valley Project:

Aim: The main aims of the Multipurpose River Valley Projects are:

1. Controlling flood
2. Supply of irrigation water
3. Helping in the production of hydroelectricity
4. Controlling soil erosion
5. Supplying drinking and industrial water etc.

Results: Dams across rivers are built to regulate the supply of water during dry periods. But silt carried by the river gets deposited in the reservoir. Below the reservoir (dam), the river is free from a load of silt.

Therefore, it erodes its own valley and surrounding area. In some rivers, the construction of a dam reduces the volume of water and causes the deposition of silt in the lower course. This results in the rise of the river beds and consequently, it leads to floods.

“Class 8 Geography Human Activities and Environment notes, WBBSE syllabus”

After the floods, the river may flow in a new channel. Thus, the river changes its course. The construction of the dam checks the deposition of silt in the lower course of the river. Sometimes the silt contains valuable nutrients.

The area of the lower course of the river is deprived of such nutrients. Thus fertility of the soil is reduced and the yield of crops falls. The dams also check the free movement of fish and other organisms in the river.

Chapter 7 Human Activities And Environmental Degradation: Results Of Environment Degradation

Due to the degradation of the environment, people are forced to migrate because of the scarcity of food and energy resources. Natural hazards like droughts, floods, pollution, and accidents (due to chemical disasters, and earthquakes which occur at weak points of dams) are taking a heavy toll on human life.

 

 

 

 

 

 

 

 

Human Impact On The Environment

Faster development of resources is leading to the degradation of the environment but it should be noted that the degradation of resources creates some problems and man is facing these from the environment as well as from the earth.

“WBBSE Class 8 Human Activities and Environmental Degradation notes, Geography Chapter 7”

It decreases biodiversity and the balance between demand-supply. It causes global warming, climate change and depletion of natural resources also.

Some Evidence of Environmental Degradation:

There is some evidence which are related to environmental degradation.

Bhopal Gas Tragedy (1984):

This is an important example of a chemical disaster. Deadly Methyl Isocyanate(MIC) gas leaked out of a cracked tank of the chemical and pesticide plant of Union Carbide. About 4000 people and innumerable birds and animals died. Over 2 lakh people were affected by the disaster. People of this region are still bearing the brunt.

 

Nuclear Disaster in Chornobyl, Ukraine (1908) and Fukushima in Japan (2011):

Nuclear disasters like the ones in Chornobyl, Ukraine and in Fukushima, Japan, remind us of the curses of modern technology.

How can Environmental Degradation be controlled:

In recent times the economic activities of man have increased to the satisfaction of our needs which causes environmental degradation. Most of the resources face depletion because of environmental degradation.

This may result that the survival of man on earth becoming difficult. Environmental degradation must be checked immediately. The survival of mankind depends upon the fact that he has to live in harmony with the elements of nature.

“Class 8 WBBSE Geography Chapter 7, Environmental Degradation easy explanation”

So as conscious citizens environmentalists are campaigning and making people aware of their mission and visions to save the environment as well as the Earth. According to them, the following steps may be taken to save the environment.

1. Education and Awareness Programme: Illiteracy and lack of awareness are the main reasons for environmental degradation. It should be taken different plans to eradicate illiteracy and increase awareness about environmental issues.
2. Control of the Utilization of Wealth: It has become essential that the consumption of resources (which increases pollution) in developed countries must be reduced. Per-capita consumption of wealth, as well as energy, needs to be decreased.
3. Uses of Renewable Resources and Recycling Process: Resources should be recycled and con s users should be encouraged to use renewable or reusable commodities.
4. Must be checked Population growth: Population growth in developing countries must be checked so that the resource is conserved for future generations. The help of vigilance personnel may help to maintain of the balance between population and natural resources in a country.
5. Development in Planning way: Attention must be paid on planning and should be assessed before the implementation of the development projects by the government or others.
6. Conservation of Biodiversity: Conscious efforts should be taken to prevent the loss of biodiversity. It should be allowed all animals and plants to grow in their natural habits.
7. Increasing Reforestation: It should be restricted the deforestation and encouraged to reforestation.
8. Uses of Suitable Resources: Uses of alternative and pollution-free resources as well as sources of energy must be encouraged.
9. Awareness Programme with the Assistance of Mass Communication: To increase environmental awareness among the people it should be taken the assistance of mass- media and vigilance personnel.
10. Lawmaking: The national and local governments must prioritise environmental issues. Stricter laws must be formulated and implemented for the conservation of the environment.

“WBBSE Class 8 Chapter 7 Geography, Human Activities and Environmental Degradation solutions”

What should be done: Progress and survival of mankind is not possible without development. Development is necessary, and so is saving the environment. Development and conservation of the environment have to be carried out simultaneously. Hence the eco-friendly way to progress and prosperity are to be traversed. To ensure this, environmentalists suggest ‘sustainable development’.

“WBBSE Class 8 Geography Chapter 7 notes, Human Activities and Environment PDF”

The idea of sustainable development is dynamic, hence the definition varies in different countries in tune with their cultural, political and economic traditions. Generally, sustainable development refers to development aimed at the optimum use of natural resources in the present scenario, so that development can go unhampered while also preserving reserves of nature and the potential of human society to develop, for future use.

There are some points of agreement which are as follows:

1. Its attainment is improbable in the short run.
2. Its basic principle is equity and justice.
3. The approach towards sustainability is balanced and integrative.
4. There are different ways, although the goal is common.
5. It views nature not only as a resource but also as the ‘earthly womb’ necessary for our survival.

The Objectives of Sustainable Development are as follows:

1. The basic needs of all, viz., the rights to live, food, shelter, clothing, education, health, etc., should be kept in mind.
2. An agri-articulated development process without disturbing ecological balance and environmental sanctity is to be initiated.
3. All countries of the world must cooperate to create a conducive environment in which the above two goals will be fulfilled.

India is a rapidly developing country. Extraction of different types of resources and execution of modern agricultural methods, construction of infrastructure like roadways, railways, industrialization, urbanisation and implementation of various projects are being carried out in different parts of the country.

“WBBSE Class 8 Geography Chapter 7, Environmental Degradation important questions”

Along with such developments, the occurrence of hazards, accidents and as well as environmental degradation also happen. 13 of the 20 most polluted cities in the G20 countries are in India as reported by the World Health Organization.

The main environmental problems of India are reduction in forest resources, misuse of resources, degradation of agricultural lands as well as food shortage, deterioration of public health standards, unplanned development, poverty and loss of biodiversity.

According to a report of the World Bank, recent environmental degradations cost in India is about $80 billion (about Rs. 480,000 crores) every year.

A survey on environmental degradation, conducted in 132 countries of the world reveals India ranks at the 126th position. Our country is placed right at the bottom of the list in terms of the adverse effects of air pollution on the people.

Though the problems of illiteracy and poverty which faced by. Indians cause the degradation of the environment but it is true that there are conscious citizens also. They are not sitting idle and they have started campaigning and participating in different movements which have been organized in India.

The important environmental movements are as follows:

1. Chipko Movement (1973) started in Uttar Pradesh.
2. Silent Valley Movement in Kerala (1976).
3. Protection of the Narmada Movement in the leadership of Medha Patekar. The movement is going on till now.
4. The movement offers Dam Project by the leadership of Sunderlal Bahuguna.

Environmental Degradation Problem related to the Green Revolution: The success of the ‘Green Revolution’ is mostly found in the wheat belt of North-Western India (mainly in Punjab and Haryana). But present negative side effects resulted in the form of environmental degradation.

A sudden rise in the use of chemical fertilizers and pesticides has harmed the long-term fertility of soil and caused water pollution. Even in the case of chemical fertilizers, the ideal N : P: K ratio of 4: 2: 1 has not been maintained.

Besides high yielding seeds speed up vital genetic defects. The supply of water in irrigation as wasteful useful water, the water table has fallen sharply and other harmful effects of injudicious use of water include waterlogging, silting, salinisation, alkalinisation etc.

Environmental Degradation in East Kolkata (Dhapa, Salt Lake etc.): At present environmental degradation is.blatantly visible in the ‘Salt Lake’ Wetlands of East Kolkata. The wetlands have been filled and used as construction sites for high-rises. As a consequence, th

e groundwater level has fallen. The quality of groundwater decreases and salinity increases.

Acquisition of cultivable lands and felling of frees for the construction of buildings have disturbed the ecological balance as well as environmental degradation.

Besides, dumping of garbage in the Dhapa area has contaminated water and soil substantially and also made the air stink.

What can the students of Class 8 do in spite of all their limitations:

1. Keep the school, home and neighbourhood clean. Plant trees on school premises in -the yard or in the rooftop plant pots or in the roadsides.
2. Initiate a ‘Green Compaingn’ is possible, in nearby areas.
3. They should be conscious and reasonable when they use electricity and water. They should not waste such resources.
4. They should reduce domestic waste as far as practicable and stop using materials like nylon, plastic etc.
5. They should avoid overuse of electrical equipment like A.C. machines, refrigerators etc. and use of cosmetics like scents, creams, deodorants etc. They should not burn many
6. quantities of fossil, fuels (coal, petroleum etc.).
7. They should organize or participate in awareness programmes, seminars, rallies, debates etc. in their school or any institution nearly to promote their own and public awareness of
8. environmental degradation as well as environmental issues.

WBBSE Notes For 8 Class Middle School Geography

Chapter 8 Some Neighbouring Countries Of India

Neighbouring Countries

A person who dwells near another is called a ‘neighbour’. People living around us are our neighbours. It is very important to keep good relations with neighbours. The adjoining countries or the countries lying near or beside a particular country are called ‘neighbouring countries.

As a good neighbour, a country should maintain a good relationship with its neighbouring countries because of the following reasons:

Read and Learn all WBBSE Notes For 8 Class Middle School Geography

1. No country is totally self-sufficient. Every country imports certain commodities and exports its surplus commodities, So there is an exchange of commodities to meet each other’s needs. But trade with the neighbouring countries can be carried only if good relations are maintained with them. So good relations with the neighbouring countries are essential for the growth of trade and commerce.
2. A good relationship with the neighbouring countries considerably determines our peace and prosperity; because a strange relationship with a neighbouring country entails high expenditure on defence accounts curtailing expenditures on social and economic uplift of the people.
3. Good relation on the other hand not only reduces defence expenditure but can also take advantage of mutual benefits derived from trade, technical know-how and a larger market for selling products.
4. Good fences made good neighbours. If good relations are not maintained border disputes arise and cause tension, Indo-Pak and Indo-China wars over our northern borders are good examples. This hampers the economic development of a country. So there should be good relations with the neighbouring countries.
5. A country should try to maintain a good relationship with neighbouring countries for the establishment of industries. It helps to collect raw materials and market for its finished products in the neighbouring countries which are not at all developed in industries.
6. Friendly neighbouring countries may act as buffer states during wartime’.
7. In the international field, a country should follow the policy of life and let live. It stands for international peace and understanding. The formation of SAARC explains the importance of mutual understanding among the nations of the sub-continent.
8. A country should maintain a good relationship with its neighbouring1 countries to exchange cultural heritage (education, music etc.) with them. It promotes cultural progress with the spirit of mutual cooperation.

Neighbouring Countries Of India

The neighbouring countries of India:

The neighbouring countries of India are —Nepal, Bhutan, Bangladesh, Myanmar, Srilanka, Pakistan, Afghanistan, China and Maldives. (Afghanistan, China and Maldives are out of the syllabus).

According to the size and population of China is the largest and most populated neighbour of India. The smallest neighbour of India is Maldives Island.

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“WBBSE Class 8 Geography Chapter 8 notes, Some Neighbouring Countries of India”

Indian Sub-continent: During British rule, the entire areas comprising India, Pakistan, Bangladesh, Sri Lanka, Nepal and Bhutan would form a well-defined geographical and geopolitical unit because they have such similarities. in natural and cultural features.

The then ruler, i.e. the English people would call the entire geographical unit surrounding India a sub-continent. This sub-continent has been separated from Asia by the waters of the Indian Ocean on the south and by the inaccessible mighty walls of mountains on the north, northeast and northwest. After the partition even today in common parlance India is called a ‘sub-continent’.

SAARC: The formation of SAARC explains the importance of mutual understanding among the nations of the sub-continent. For the purpose of peace,-stability,‘and economic progress, India and her neighbouring countries established SAARC (South Asian Association for Regional Co-operation) in 1985.

India, Bangladesh, Nepal, Bhutan, Srilanka, Pakistan, Maldives and Afghanistan, these eight countries are members of SAARC. The Headquarters of SAARC is situated at Kathmandu in Nepal. The main purpose of SAARC are to keep good relations among the member countries. It facilitates increased cooperation in the field of culture and

Countries	Nepal	Bhutan	Bangladesh	Myanmar	Srilanka	Pakistan
Capital	Kathmandu	Thimpu	Dhaka (Dacca)	Naypyidaw (Yangon)	Sri Jayawardena-pura Kotte	Islamabad
Area	140792 sq. km	47913 Sq.km	144004 Sq.km	678500 Sq.km	65604 Sq.km	803936 Sq.km
Population	28563000	691000	156051000	48138000	21325000	176243000
Highest Peak	Mount Everest (8848 m)	Kula Kangri (7554 m)	Keokradong (1232 m)	HKakabo Razi (5581 m)	Pidrutalagala (2627 m)	Tirich Mir (7708 m)
Longest River	Kali-Gandak	Manas	Padma-Megana	Irrawaddy	Mahawali Ganga	Indus
Main Language	Nepali	Dzongkha	Bengali	Burmese	Sinhala / Sinhalese	Urdu
Main Agricultural crops	Rice, Wheat, Jute, Maize, Jowar, Orange	Wheat, Barley, Maize, Apple, Orange, Cardamom	Rice, Jute, Tea, Sugarcane, Wheat, Oilseeds	Rice, Maize, Millet, Tobacco, Oilseeds	Rice, Tea, Rubber, Coconut, Spices, Oilseeds.	Rice, Wheet, Maize, Cotton
Main Industry	Paper, Jute Cotton textile, Leather	Lumbering, Jam, Jelly, Drink Processing, the cotton industry	Jute, Paper, Sugar, Pottery, Garments, Handloom.	Jute, Sugar, Silk	Tea, Paper, Garments, Coconut oil	Cement, Sugar, Cotton Textile Leather, Garments
Major Cities	Kathmandu, Pokhra, Biratnagar, Janakpur	Thimpu, Paro, Phuntsholing Punakha	Dhaka, Chittagong Srihatta, Khulna	Yangon, Mandalay Mawlamyine	Colombo, Kandy, Jaffna, Ratnapura	Islamabad, Karachi, Lahore Peshawar

Chapter 8 Some Neighbouring Countries Of India: Nepal

The official name of the Nepal Federal Democratic Republic of Nepal’. After 240 Years under the Shah dynasty, Nepal abolished its monarchy and became a republic in May 2008. Nepal lies between China and India in South Asia.

The mountainous heart of Nepal consists of the towering Himalayas (including Everest, the highest peak in the world). There are 16 aks about 8000 metres). There are many beautiful valleys in this region as Kathmandu Pallev Pokhara valley etc.

The climate of Nepal is Temperate Monsoon type. Nepal has covered r forests (over 50% of its area). The majority of the inhabitants are farmers. Industrially Nepal is not developed. The communication system is very underdeveloped.

“Class 8 WBBSE Geography Chapter 8 notes, Neighbouring Countries study material”

Tourism Industry of Nepal: Tourism is the largest industry and main earning source of foreign money of Nepal. There are many beautiful places, gardens, and highways decorating the towns There are ten highest mountain peaks of the world situated in Nepal.

These are attractive to most of tourists. The mountaineers of the world come to Nepal for mountaineering. The most attractive tourist centres are the temple of Pashupatinath, Buddhist monasteries, Tribhuvan University, Durbar house, New Market etc.

The famous archaeological sites oPatan ancPatgaon is located nearby Kathmandu. Kathmandu is also the headquarters of SAARCP Pokhra is also a famous tourist town (The second largest city of Nepal). The white snow-covered peaks of the Himalayas look beautiful from this city. The hotel industry has developed here.

“WBBSE Geography Class 8 Neighbouring Countries, Chapter 8 key concepts”

Tracking can be done from here to Muktinath. Kapilavastu (Lumbini) situated in the Terai region, to the south of Nepal is the famous birth place of Lord Gautam Buddha etc. are attracted tourists.

Tourists coming to trek in the mountain and climb the peaks contribute to national income because Sherpas benefit from the mountaineering boom and tourism in the Everest region, owing much of the lodging and transportation. So, it is truly called that tourism is the largest industry and source of foreign money as well as the main earning source of Nepal.

Chapter 8 Some Neighbouring Countries Of India: Bhutan

The official name of Bhutan kingdom of Bhutan. Bhutan is a tiny, remote and impoverished country between two powerful neighbouring countries, India and China. Bhutan’s ancient Buddhist culture and mountain scenery make it attractive for tourists, whose numbers are limited by the government.

Forests still cover nearly 75% of Bhutan’s land area. Almost all trade is with India. Due to showers with thunderstorms, Bhutan is known as the Land of Thunder Dragon’. The climate of Bhutan is a Moist Temperate Monsoon type.

“WBBSE Class 8 Chapter 8 Geography, Some Neighbouring Countries of India solutions”

No important minerals are mined in Bhutan, so large industries have not developed here. The Chukha Hydel project has been constructed with the cooperation of India. There are no railway lines.

Fruit Processing Industries Of Bhutan: There are different fruits like apples, oranges, pineapples etc. are produced in Bhutan. So, fruit processing mostly in small factories is important. u an is world famous in making jam, jelly, squash, and pickle from these fruits.

Countries Near India

Chapter 8 Some Neighbouring Countries Of India: Bangladesh

The official name of Bangladesh is ‘Peoples Republic of Bangladesh’. Bangladesh became an independent country on 16th December 1971. Bangladesh is surrounded by India on three sides. It is a low lying country formed by the alluvial plain of the river system of the Ganges and the Brahmaputra.

Bangladesh is a network of rivers. It has a Tropical Monsoon climate. The Sundarbans mangrove forest—one of the largest in the world and home of the Royal Bengal tiger is situated on the southern portion of the estuarine Gangetic delta near the Bay of Bengal.

“WBBSE Class 8 Geography Chapter 8, Neighbouring Countries of India study guide”

Bangladesh is an agricultural country with 70% of the land being used for agriculture. There is a little mineral resource in Bangladesh. A large amount of natural gas is found in the Sylhet region. Industrial development has occupied, very slightly in Bangladesh.

Agro-based Industry of Bangladesh: Due to the lack of mineral resources large-scale metallurgical industries have not been set up. Bangladesh is an agrarian country.

However, some agro-based and forest-based industries have developed here, like-jute industry, paper industry, tea Industry, sugar industry, cotton-textile industry, silk-textile industry and food processing industry etc. The main industry of Bangladesh is the jute industry with nearly about 80 jute mills are situated at Dhaka, Narayanganj, Khulna, Daulatpur, Chittagong and other cities.

“WBBSE Class 8 Neighbouring Countries notes, Geography Chapter 8”

The famous ‘Adamji Jute Mill’ is located in Damrai, near Narayanganj. The handloom (Tant) at Tangail, and Maslin at Sonargaon near Dhaka are world, famous. Bangladesh is developed in handicraft and cottage industry, like the conch industry of Dhaka, combs of Jessore etc. Besides these cement, ship repairing, sugar refining, and chemical fertilizer industries have been established here.

Chapter 8 Some Neighbouring Countries Of India: Myanmar

The official name of Myanmar (Burma) republic of the Union of Myanmar”. It is a resource-rich country with a strong agricultural base. Myanmar’s Irrawaddy Basin is surrounded by forested mountains and plateaus. Most people live in the fertile valley and delta of the Irrawaddy river. The climate of Myanmar is Tropical Monsoon type.

Countries That Border India

Mineral and Forest resources of Myanmar:

Mineral Resources: Myanmar is rich in mineral resources. Some important minerals are- mineral oil, tin, tungsten or Wolfram, lead, zinc, silver and precious stones.

Mineral oil is found in the Irrawaddy and Chindwin river valleys, mainly irMinbu, Enang Young, Chak etc. Tin is found in the Mouchi and Tyavoy regions of Tenasserim. In the Shan plateau region lead, Zinc, manganese, tungsten and silver are found. In this plateau, precious stones are found in Mogok. World-famous Ruby is found here. Some low-grade iron-ore, nickel and copper are also mined here.

“Class 8 WBBSE Geography Chapter 8, Neighbouring Countries easy explanation”

Forest resources: About 70% of the country is covered with forests. Different types of forests are found in Myanmar. In the forest areas sal, teak, poma trees are found in the deep interior. These trees are valuable hardwoods ‘Burma teak’ is famous in the world.

In the plains, deciduous trees are found. In the rain shadow areas in the middle of the country, trees are fewer and tall grasses are found. Important Evergreen trees like Garjan, Chaplash, Mahogony etc. and deciduous trees like Arjun, Sal, Teak etc are the valuable forest resource of Myanmar.

Chapter 8 Some Neighbouring Countries Of India: Srilanka

The official name of the Srilanka Democratic Socialist Republic of Sri Lanka’. Srilanka, known as Ceylon until 1972, is a tropical island lying near the southern tip of India and the Equator. From the coast, the land rises to a central plateau, where tea plantations are found. Srilanka has an Equatorial climate.

Agriculture of Sri Lanka: Agriculture is the main occupation of the people of Srilanka. Rice is the most important crop and yields are high due to the two rainy seasons in the year. Tea and rubber is cultivated intensely in the extensive highlands in the centre of the country.

Though small in size Srilanka ranks third after India and China in tea production. Srilanka earns high foreign exchange from the exports of tea and rubber. Tobacco is an important cash crop in the Jaffna, peninsula to the north of the country. Coconut is also an important cash crop of Srilanka. In coconut production, Srilanka ranks fourth in the world.

“WBBSE Class 8 Geography Chapter 8 notes, Neighbouring Countries PDF”

The various spices produced in Srilanka are cinnamon and clove. As cinnamon production is high, Srilanka is also called the “Cinnamon Island”. Other crops produced are maize, oilseeds, millets, cinchona, varieties of vegetables, bananas etc.

Mineral Resources: Srilanka is famous in mineral extraction. Srilanka occupies the first position in the production of Graphite. Precious stones like Saphire, Ruby, Cat’s eye etc. are produced in Srilanka.

These minerals are mainly mined from the old rocks of the central mountains. Gem City, the sabargammoya produces varieties of precious stones etc. Some limestone is produced from the northern Jaffna peninsula. Some bauxite is also mined from the central highland.

Chapter 8 Some Neighbouring Countries Of India: Pakistan

The official name of Pakistan is the Islamic Republic of Pakistan’. It is located along the north¬ western frontier of India. Pakistan is surrounded by Afghanistan and Iran on its north and west and India on its east and southern region and the Arabian Sea in the south.

The eastern and southern parts of Pakistan are dominated by the Indus river and its tributaries. West of the Indus, the land becomes increasingly arid and mountainous. The climate of Pakistan is dry and extreme type.

Countries Close To India

Rainfall is low here and summer temperatures shoot up while in winter they drop. Thus summers are very hot and winters are very cold Jacob Abad in the province of Sind records the highest temperature of 52°C in summer. Lack of rainfall has allowed less area to be under forest. In the arid regions xerophytes are found.

Irrigation and Agriculture of Pakistan: In Pakistan, the rainfall is very low, so irrigation is essential for cultivation. Canal irrigation is the most important. A large number of perennial canals are found in West Punjab.

The upper and Lower Jhelum canals, the upper and lower Chenab canals, and the lower Bari Daab canal from the Ravi are the most important of them. In Sind, the Liyod or Sukkur Barrage has been constructed over the Indus at Sukka. From the river, a large number of canals have been constructed to irrigate different parts of Sind.

In Baluchistan, the water dries up as soon as it comes down from the hills to the dry sand at the foot. So water of the hill streams is carried to the agricultural lands through underground tunnels. This system is called ‘Karez’.

“WBBSE Class 8 Geography Chapter 8, Neighbouring Countries important questions”

In West Punjab and Sind, there are wells. Besides, iyo barrage, other dams have been constructed over other parts of the Indus and its tributaries for irrigation. Eg. Mangla Dam over the Beas river in the north, Gulam Mohammad Dam over the Indus, Jinnah Dam etc. Agriculture of Pakistan depends largely on irrigation.

Agricultural of Pakistan: Pakistan is prosperous in agriculture due to the irrigation system in spite of different problems. Extensive irrigation has made large areas of the semi-deserts and deserts convert to productive farm lands overcoming the main problem of low rainfall.

In Pakistan, wheat and cotton are the most important crops. The other important crops are rice, sugar- cane, maize, millet etc. Wheat is cultivated in West Punjab, Sind, and. N.W. Frontier Province’

“Class 8 Geography Neighbouring Countries notes, WBBSE syllabus”

It is grown there in the weil-irrigated areas. West Punjab is the most important wheat-producing, area of Pakistan. Cotton cultivated with the help of canal irrigation is of very good quality, Rice grows in river valleys and deltaic regions.

N. W Frontier Province, sugar cane, grows in the river valleys. Different types of fruits like ‘apples, dates, peaches etc are also important agricultural products of Pakistan.

Neighbouring Countries	Export goods of India	Import goods of India
Nepal	Iron and Steel, cement, sugar, tea, salt, car ‘ and spare parts, cotton, chemical fertilizer, garments, petrochemical goods etc.	Timber, hides and skin, oilseeds, pulses, carpet, raw Jute etc.
Bhutan	Textile goods, coal, cement, medicine, engineering goods, iron, steel, paper, salt, sugar etc.	Different fruits, jam, jelly, cardamom, fur and fur-based garments, timber, hides, wool, Ivory, the tail of yak arid, and wax.
Bangladesh	Wheat, rice,- cotton/ cloth and yarn, coal, machinery, books, medicine, video cassette, music cassettes etc.	Raw jute, fish, hides and skin, tea, paper pulp, books etc.
Myanmar	Coal, iron and steel, cotton textiles, jute goods, medicine, machines, coal, means of transportation etc.	Rice, mineral oil, silver, tin, tungsten, teak, lead, precious stones, rubber, cotton, sandalwood, and pulses.
Srilanka	Textile goods, jute goods, iron and steel, petroleum products, video cassettes, music cassettes etc.	Oil cake, tea, graphite, precious stones, rubber, copper, clove, coconut products hide etc.
Pakistan	Spices, medicines, rubber goods, tobacco, iron and steel, machinery, paper, coal, ‘ sugar, pharmaceuticals etc.	Cotton, hides, wool, rocksalt, textile, goods, dried fruits, wheat, carpets and woollen garments

 

WBBSE Notes For 8 Class Middle School Geography

Chapter 10 South America

Introduction Of South America: The Continent of South America is situated to the south of North America. Once it was connected to North America through the ‘Isthmus of Panama’.

In 1914, South America becomes separated from North America by constructing the Panama Canal cut through the Isthmus of Panama. The continent was unknown to the Europeans for a long period. Therefore, when the continent was discovered by the Europeans, they called it as ‘New World’.

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South America forms a part of Latin America which includes the states of Central America south of the United States and the West Indies. Latin was the ancient language used by Romans in the past. Modern languages of Spanish, Portuguese, Italian, and French are derived from Latin.

“WBBSE Class 8 Geography Chapter 10 notes, South America”

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People from southern Europe speaking these languages settled in this part of the Western Hemisphere. Therefore, this part of the Western Hemisphere is called, ‘Latin America’.

Location: South America is situated between 81°21′ West longitude in the west and 34°50′ West longitude in the east; and 12°28′ North latitude in the north and 56° S latitude in the south. Since nearly. 85% of the continent falls within the southern hemisphere, it is called a ‘Southern Continent’.

The continent is also called the ‘Continent of Western Hemisphere’ as it is entirely located to the west of 0° longitude. South America is a triangular-shaped continent that is wider in the north and gradually tapers to a point in the south. It stretches for 7562 km from north to south and for 5310 km from west to east as its widest part.

Geography Class 8

Boundary: The continent of South America is bounded on the east by the Atlantic Ocean, on the west by the Pacific Ocean, on the north by the Caribbean Sea and the Panama Canal and on the south by the narrow Drake Strait and Antarctic Ocean.

Tierra del Fuego, an igneous island, lies off the southeast coast of South America and is separated from the mainland by the Strait of Magellan. Cape Horn is the southernmost tip of the continent.

Area: South America occupies about 17.8 million square kilometres area. It is the fourth largest continent of the world according to its size and population. Its area is six times greater than India.

Population: The population of South America is about 385 million (385000000).

Geographical Importance: South America is a typical continent exhibiting all kinds of physical and economic features. These are as follows:

Island Continent: South America is bordered on all sides by ocean waters. So it is called an ‘Island Continent’.

Presence of various types of physiography: There are lofty young fold mountains of the Andes; the Great Central Plain covered by the Llanos, the Selves, the Gran Chaco and pampas; the double eastern highlands of Guiana and Brazil and the deeply indented coastline of the southern end.

“Class 8 WBBSE Geography Chapter 10 notes, South America study material”

A continent of contrasts: South America is a continent of contrasts. The hot wet equatorial forests of the Amazon Basin and the Atacama Desert of Peru-the driest of the world, the high barren plateau of Bolivia, the temperate grassland of Argentina and the Mediterranean coast of Chile-all differ widely in climate and vegetation.

Rich in native flora and fauna: The continent is rich in native flora and fauna which are peculiar to other continents. The hevea brazillensis which yields rubber is a native tree of South America. Native animals include the alpaca and vicuna which are prized for their wool and the llama.

Presence of dense forest: The entire northern part of the continent is covered by dense evergreen rain forests, called ‘Selvas’ through which light cannot reach inside. The Selva is also called the ‘Land of Twilight’.

Developed in agriculture: South America has always been mainly an agricultural continent, exporting agricultural products to Europe and North America.

Developed In Industry: Though agriculture is still the chief occupation manufacturing industries have also developed in Argentina, Brazil, Chile and Peru.

Abundance In Raw Materials: There are sufficient raw materials in South America which are needed for different industries, such as:

Minerals like:
(1) Iron ore,
(2) Copper ore,
(3) Bauxite;

Crops like:
(4) Coffee,
(5) Cocoa,
(6) Sugarcane,
(7) Rubber,
(8) Cotton etc.;

Animal-based raw materials like:
(9) Wool,
(10) Meat,

Leather and forest-based raw materials, like:
(11) Timber.

Potential In Power Resource: Though there is a scarcity of power resources there is high potentiality in the generation of hydel power by the turbulent rivers and thermal power.

Prospective continent: With its immense resources awaiting development, South America’s future holds great promise.

Chapter 10 South America Physical Features of South America Physiographically

South America may be divided into five divisions-

1. The Western Mountains,
2. The Northern Plateau,
3. The Eastern and The Central Highlands,
4. The Central Plains and
5. The Coastal Plains

The Western Mountains: The Andes Mountains, also known as the ‘Western Cordilleras’ is the most prominent feature of the continent. The Andes Mountains extend continuously parallel to the west coast for a distance of over 7250 kilometres.

It is the longest mountain in the world. It is broad in the north in Bolivia (about 640 kilometres) and gradually becomes narrow in the south. The mountains contain high peaks such as Mt. Aconcagua (7021 meters), (6277 m) and Cotopaxi Chimborajo (5896 m).

Chimborgo is the highest active volcano in the world. Cotopaxi is the second-highest active volcano in the world. Aconcagua is the highest peak of the Andes. There are many volcanic peaks in the mountain ranges. The high peaks are permanently covered with snow and ice.

The Andes is the world’s longest as well as the second loftiest young fold mountains. The Andes mountains is frequently affected by earthquakes.

The Andes mountains consist of two or three parallel ranges with basins of plateaus between them. Central cordillera runs through the middle of Colombia in a north-south direction.

“WBBSE Class 8 Geography Chapter 10, South America study guide”

The Occidental mountain range lies west of central California and the Oriental mountain range lies east of the central Cordillera. The southern part of the Oriental mountain range is known as the ‘Real mountain’ which stands along the border between Chile and Argentina.

Lake Titicaca located on the Andes along the border between Peru and Bolivia is the highest lake (3800 m) of the world and also the largest lake of America. The Uspallata pass lying to the southwest of Aconcagua is the only break in the continuous chain of the Andes.

The Northern Plateau Region: The region that extends from the Andes in the western part of the continent to the Atlantic coast in the east is called the Northern Plateau Region.

Due to the processes of erosion and denudation by rainfall, river and wind, the plateau has been reduced to a low height. This region covers Venezuela, Guyana, Surinam and Guiana and is also known as Guiana s 48 Highland. In Venezuela the plateau is highest where Merida is the highest mountain and the highest peak is Marta (5105 m).

The Central and Eastern Highlands: There is another highland in South America. In the east of the continent, it is known as ‘Brazilian Highland’ and in the central region of the continent as ‘Mato Grosso’,

Pacific Ocean Plains Ocean Eastern High Land Atlantic which, actually, links the Andes Mountain in the west and the Brazilian Highland in the east. Brazilian Highland slopes very steeply to the Atlantic coast in the east, while it descends gently to merge with the Central Plains in the west. The greater part of the plateau is occupied by the ‘Campos’ grassland.

The Central Plains Or Lowlands: The Central Lowlands or Plains lie between the Eastern Highlands and the Andes. They consist of four areas from north to south. These are as follows:

The Plains Of The Amazon Basin: This is the largest and northernmost part of the plain. This plain is located in the equatorial region. So a major portion of this plain is covered by dense evergreen rain forests called ‘Selvas’. The slope of this region is from west to east.

The Plains Of The Orinoco Basin: The Orinoco river basin in Venezuela and Colombia has formed a narrow plain extended in the southwest to northeast direction. ‘Llanos’, the tropical grassland covers this plain.

The Plains Of The La-Plata Basin: La-Plata, the most important estuary of the Parana -Paraguay and Uruguay river of the southern part of south America has formed another narrow plain extending from the north to the south through the countries of Bolivia, Paraguay, Uruguay and Argentina.

The Pampas Plain: An extensive temperate grassland called ‘Pampas’ lies to the south of the La-Plata in Argentina. In the north the grassland where some deciduous trees are found with scattered presence of scrubs it is known as ‘Granchaco’. The southern part of the Pampas is very dry and has formed the Patagonia, Desert.

The Coastal Plains: There is a very narrow coastal strip bordering the Pacific Ocean coast of Ecuador and Colombia as the Andes rise very steeply from the shore of the Pacific Ocean. The coastline of South America is almost smooth except in the southwest where it is broken. Many fiords have formed by glacial erosion through which the sea water enters the continent.

Many islands are also found in the ocean, such as the Galapagos islands lie off the coast of Ecuador, Juan Fernandez lies off the coast of Chile; Tierra del Fuego and Falkland island lie off the coast of Argentina and Trinidad Tobago, Barbados and Grenada islands lie off the coast of Venezuela.

Chapter 10 South America Drainage System Or Rivers Of South America

Many rivers are found in the continent of South America. Rising in the Equatorial regions most of the rivers of the content supply more water.

The plateau of Mato Grosso, located in the central part of South America, acts as a water divide between the northern and southern parts of the continent. Most of the rivers of the continent have organised either in the Mato Grosso or in the Andes and flow eastward to the Atlantic Ocean.

The characteristic features of the rivers or drainage system of South America are as follows:

1. Most of the rivers of South America are rain-fed and originate from the Equatorial region of the continent.
2. The rivers are perennial as they are fed by snow or equatorial convectional rain. Some of these rivers are suitable for the generation of hydel power.
3. Most of the rivers are long in length and large in volume.
4. Most of the rivers originated from the Mato Gross plateau or the Andes mountains.
5. There are some west-flowing rivers which originate from the Andes mountains are short in length.
6. Except for the Orinoco river, no other river has formed a delta near its mouth.

According to their direction of flow rivers of South America may be grouped into following categories :

1. East flowing rivers,
2. North flowing rivers,
3. South-flowing rivers and
4. West flowing rivers.

Important Rivers Of South America:

Types Of The Rivers	Name of the Rivers
East flowing Rivers.	The Amazon, Orinoco, Sao-Francisco
North flowing Rivers	Madeira, Purus, Tapajos, Xingu, Araguaia, The Magdalena.
South flowing Rivers	Paranaiba, Parana, Paraguay, Uruguay, Rio-de-la Plata, Salado, Colorado,Rio-Negro, Chico, Rio Branco.
West flowing Rivers	Short but turbulent rivers which originated in the Andes and flow into the Pacific Ocean.

 

East Flowing Rivers:

(1) The Amazon River System: The Amazon river, the chief river of South America is the World’s greatest and mightiest river. This is the longest river of South America and the Second longest river of the world (6447 km). In 1541, the great Spanish traveler ‘Orellana’ called this river as ‘Amazons’.

It owes its name to the race of female warriors called the ‘Amazons’ of Greek legend. The river basin is also called the ‘Amazonia’ i.e. ‘the land of the female warriors’. The river basin covers about 7:04 million square kilometres which is the world’s largest river basin.

The source of the river Amazon is considered as a lake which is located on the top of the Andes. Another opinion is that the river Amazon originated from Mt. Mishmi (5597 m) on the Andes in Peru and then flows northward.

Rising as the ‘Maranon’ in the central Peruvian Andes, it is joined by another two headstreams including the ‘Napo’ and the ‘Ucayali’. Then it escapes from the Andes through narrow gorges and flows eastward over the lowlands to meet the Atlantic off north-eastern Brazil.

The river is fed by more than one thousand tributaries flowing down from Peru, Bolivia, Ecuador, Colombia, Venezuela and Brazil. The seven tributaries namely Madeira, Jurua, Purus, Japura, Tocantins, Negro and Xingu are longer than 2000 kilometres.

The Madeira (3350 Km long) is the longest tributary that flows from Bolivia. On the other hand, the Negro (2253 km long) though shorter in length, is the largest tributary of the Amazon.

Rising in the equatorial regions of Colombia, it supplies more water to the Amazon than any of the other tributaries. It is estimated that 20% of all the water that runs off the Earth’s surface is carried by the Amazon.

The width of the river varies from 1.5 km to 14 km and near the mouth it is 80 km. So it is no wonder that the Amazon is called the ‘River Sea’. The large volume of freshwater discharged by the river makes the seawater less salty for more than 160 km from the shore.

“WBBSE Class 8 South America notes, Geography Chapter 10”

The river Amazon is navigable up to 3200 km from its mouth. A large volume of water with great velocity is discharged through the wide mouth of the Amazon river to the Atlantic Ocean.

The mouth of the Amazon river is quite wide and water from the ocean enters the river during high tide. Ocean currents are also very strong in this region. Due to such conditions, no delta has been formed in the mouth of the Amazon river.

The Amazon river is called World’s largest river due to the following causes :

1. The Amazon river is the second longest river (6447 km) of the world (the Nile is the longest, 6671 km).
2. The Amazon basin is the largest river basin of the world (7050000 sq. km)…
3. This basin is located in the Equatorial climatic region. Heavy
4. As the location of the Andes in the way of northeast trade winds, moisture-laden air gets obstructed by the mountain, causing heavy precipitation.
5. The discharge of water per second is 209000 cubic metres.
6. There are about more than 1000 tributaries and innumerable distributaries of the Amazon. They are quite long.

(2) The Orinoco River System: The name ‘Orinoco’ is derived from the American word meaning ‘Place of Paddle’ i.e. navigable place.

This river is flowing in the northern part of South America. After rising from the southwestern Guiana Highlands of Venezuela, the Orinoco flows for some 2736 km to meet the Atlantic where it forms a delta.

After coming down from the highland the river has crossed the dense forests, grasslands, swamps one after another flows north-eastward along the edge of the highland in a giant arc and then finally has drained into the Atlantic Ocean.

Important tributaries of the Orinoco river, that have originated either in the Andes or in the Guiana Highlands are- Meta, Guaviare and Caroni. The Carrao, a tributary to the river Caroni, has formed the highest waterfall of the world- the ‘Angel’ waterfall. It is about 979 metres high (3212 feet).

Casiquiare, another tributary to the river Orinoco has joined river Negro-the tributary to the Amazon river.

“Class 8 WBBSE Geography Chapter 10, South America easy explanation”

(3) Sao-Francises: Sao-Francisco is another important river of South America. This river is about 3200 km long. It originates in South Central Minas Gerais state of Eastern Brazil, flows north, north-east and eastward and falls into the Atlantic Ocean.

It is the main river of eastern Brazil. The river, an entirely Brazilian river, is called the ‘River of National Unity’ by the Brazilians because of its importance in navigation and as a source of hydel power.

North-flowing rivers:

(1) Madeira: Maderia is a river of west Brazil and it is the most important tributary of the river Amazon. It is about 3350 km long and formed by the confluence of Bolivian rivers Mamore and Beni at the Brazilian border. Then it flows north-eastward and falls into the Amazon below Manaus.

(2) Purus: This navigable river is one of the important tributaries of the Amazon river. It is a river of north-west and central of south America. It is about 3402 km long and rises in the Andes mountains in southeast Peru. It flows north-eastward across the Amazonas state, Brazil and falls into the Amazon river above Manaus.

(3) Tapajos: This is a river of North Brazil. It is about 1307 km long and formed by that junction of the Juruena and Teles Pires rivers on the south end of the border between the Amazonas and Para states. It flows northeastward and falls into the Amazon river at Santarem. Important rubber plantations are found along its banks.

(4) Xingu: It is a river of central and northern Brazil. It is about 1993 km long and it rises in several headstreams in the northern part of the plateau of Mato Grosso. It flows northward through northeast of Mato Grosso state and central Para state and falls into the Amazon river near its mouth.

“WBBSE Class 8 Geography Chapter 10 notes, South America PDF”

(5) Araguaia: This is a river of central Brazil. It is about 2113 km long and it rises in the south-central of the Mato Grosso state and flows northward and falls into the Tocantins river.

(6) The Magdalena: The Magdalena river which originates in the Andes mountain flows northward to drain into the Caribbean sea.

South Flowing Rivers:

(1) Paranaiba: Paranaiba is one of the headstreams of the Parana river. It is about 810 km long and rises in west central of Minas Gerais state. It flows westward and south-westward to unite with Rio Grande and form the Parana river.

(2) Parana: The Parana river is one of the chief rivers of South America (Parana is an Amerindian word meaning ‘father of the waters’). It is 4880 km long. The Parana flows mainly across high plateaus before it meets Paraguay. After this, the river flows through a broad floodplain before entering the Plata estuary.

(3) Paraguay: The southward-flowing Paraguay river (2566 km) is the main tributary of the Parana. It flows south through Paraguay before being joined by the Pilcomayo river at Asuncion. Unlike the Parana, Paraguay is a river of plains flowing across a wide stretch of marshes. The river meets the Parana at Corrientes.

(4) Uruguay: Uruguay (1662 km) is another important river. It is the Spanish from of the local Amerindian word meaning ‘the river of painted birds’. After originating from southeast Brazil, Uruguay flows in a curve and joins the Parana to form the Plata river estuary on the Atlantic coast between Uruguay and Argentina.

(5) Rio-de La-Plata: The Rio-de la Plata is a Spanish word which means ‘Silver River’. The name ‘Rio-de La-Plata’ is misleading because it is not a river at all. It is actually an estuary of Parana and Uruguay rivers between Uruguay and Argentina. It is one of the widest estuaries in the world. It is around 225 km across its mouth and is about 270 km long at its longest point.

(6) Salado: There are three south-flowing rivers in Argentina which are called Salado One of these rivers which rises in the Andes mountains and is flowing in the northern part of Argentina. It is more than 1782 km long and flows southeastwards and falls into the Parana river at Santa Fe.

The river which is flowing the western part is about 1377 km long. It flows along the south forming a boundary between Mendoza and San Luis Province turns south-eastward and emties into the Colorado river. The river of the eastern part in Buenos Aires Province is about 648 km long. It flows westward and falls into Samborombon Bay.

(7) Colorado: Originating in the Andes mountains the Colorado river flows into the Atlantic Ocean. This river is about 859 km long and flows along the Mid-Argentina.

(8) Rio-Neogro: This is the river of south-central Argentina. It is about 648 km long and flows eastward and then falls into the Atlantic Ocean.

(9) Chico: This is a river of South Argentina. It flows along the Province of Santacruz. This river is flowing southeastward and falls into the Atlantic Ocean at Santacruz.

(10) Rio-Negro Rio-Negro is a river of the north-western part of South America. It is about 2268 km. long, rises in East Colombia, where it is known as the Guai-nia flows eastward to Venezuela boundary, and then southward forming a section of the Colombia-Venezuela boundary, crosses into Brazil and continues south-eastward into Amazon river at Manaus, is joined also to the Orinoco river through the Casiquire river.

(11) Japura: This is a river of the northwest of South America. It is about 2835 km. long and rises in southwest Colombia, where it is known as the ‘Caqueta’ and flows southeastward across the Brazilian border and falls into the Amazon river.

(12) Rio-Branco/Parima: Rio Branco or Parima is a river of North Brazil. It is about 567 km. long and formed by the confluence of the Uraricoera. Tacutu; the river flows southward falls into the Rio Negro.

West Flowing Rivers: Besides the above rivers there are many streams that originate in the Andes but flow westward and fall into the Pacific Ocean. These rivers are short in length but turbulent. Therefore, these rivers are used in irrigation and the generation of hydel power.

Lakes of South America: There are a few big lakes in South America. These lakes are off two types i.e.

1. Freshwater lake and
2. Saline water lake.

Fresh Water Lakes: These are Lake Titicaca, Lake. Poopo, Lake Chiquita, etc. Lake Titicaca (8287 sq. km) located at a height of 3810 meters on the border of Bolivia and Peru is the highest navigable lake in the world. On this lake big ships ply from port to port. Lake Poopo is about 500 km. to the southeast of Lake Titicaca.

Saline Water Lake: Lake Maracaibo of northwest Venezuela is a saline water lake open to the sea. It is a shallow lake and the thick layers of sedimentary rocks under it are rich in oil deposits. In the eastern region, there are also a few small lakes in Brazil, most of them are saline water lakes.

Chapter 10 South America Climate Of South America

There are great variations in the climate of South America. This continent is called as a ‘Continent of diversified climate’ due to the following causes:

1. The continent is located on both sides of the Equator. The upper part of the continent is located in the northern hemisphere and the lower part is in the southern hemisphere. Hence, exactly opposite seasonal changes are found in the northern and southern hemispheres i.e. when summer exists in the north, winter prevails in the south.
2. Due to the Equatorial location either side of the equator has uniformly hot and humid conditions throughout the year. There is a little difference in temperature betwen summer and winter. There is no dry season.
3. The regions which are located away from the Equator to the north and south, there is greater contrast in temperature between summer and winter.
4. The Brazilian coast gets higher rainfall than the interior.
5. South of the Brazilian Plateau, the Pampas Lowlands are in the temperate zone, winters are cooler and summer are less hot. Rainfall is moderate with maximum summer.
6. Further south, the plateau of Patagonia, east of the Andes gets a low rainfall. This is a rain shadow region of the Andes. This is a temperate desert.
7. West of the Andes, the southern most region of Chile has marine or oceanic type of climate.
8. The Andes mountains region has climatic conditions varying according to height above sea-level.

Factors Affecting The Climate Of South America: There are great contrasts in the climate of South America and this is controlled by the following factors:

Latitudinal Extent: The important lines of latitude that cross the continent are the Equator (0°) in the north which passes through the Amazon estuary and the Tropic of Capricorn (232°S) which passes through the central part of the continent.

Thus the broad northern part of South America lies in the tropical zone and is hot throughout the year. While the narrow, southern part lies in the temperate zone has lower temperatures throughout the year.

Altitudinal Factor: The mountain ranges especially the Andes influence the climate in two ways. Firstly, because of its high altitude, places situated on the mountains are colder than those on the plains lying on the same latitude.

For example, Quito situated on the Equator at a higher altitude has an average temperature of about 14°C while Manaus in the Amazon lowlands, also on the Equator, has an average temperature of about 26°C. Secondly, the Andes lies close to the Pacific coast and extend from north to south.

“WBBSE Class 8 Geography Chapter 10, South America important questions”

In the north, it stands as a barrier to the trade winds which blow in from the Atlantic, and in the south, it prevents the rain-bearing westerlies from crossing over to the east. As a result, most of the Pacific coast is dry but its southern part gets rain throughout the year from the westerlies.

The steel plateau edges of the Brazilian highlands force the trade winds to rise and this results in heavy rain in the Brazilian coast throughout the year.

Prevailing Winds: The northeast and south-east trades blow toward the Equator in the tropical zone and cause rainfall in the eastern margin of the continent.

The Westerlies Rainfall: Role of the Andes blowing from the Pacific Ocean cause rainfall to the southwestern coast and Tierra-del Fuego. Central Chile gets rainfall in winter from the westerlies but remains dry in summer when it comes under the influence of the southeast trades.

Shape Of The Continent: Because of its unique shape, wider in the north and tapered in the south, major portion of the continent lies in the torrid zone.

Distance From The Sea: The moderating influence of the sea is felt in the tapered and Southern part of the continent where it is narrow. In the coastal areas of the broad northern part of the continent is also enjoy a Maritime climate. But the upper part of the continent is wider. So the climate in the interior of the northern part remains unaffected by seas and oceans.

Ocean Currents: The cold Humboldt or Peruvian current flowing along the western coast of Chile and Peru has a cooling and drying influence. So the south west coast of South America remains cool and dry.

The warm Brazilian current flowing along the eastern coast of Brazil warms the winds blowing over the sea. As a result the sea winds pick up moisture and cause heavy rain throughout the year.

Seasonal Conditions Of The Important Elements Of Climate In Different Parts Of South America:

Temperature: In the month of June-July, it is summer in the northern part of the continent where the sun is overhead. So the average temperature becomes 21°C which gradually decreases towards the south where it goes below 5°C (i.e. winter). But in the Andes and in the extreme South at Tierra del Fuego temperatures drop below the freezing point.

In December-January, when the sun is overhead south of the Equator, southern Brazil and northern Argentina being near the Tropic of Capricorn are the hottest parts of the continent with an average temperature of 30°C.

Temperature decreases to about 18°C further south and the extreme south the summer temperature is about 10°C. However, because of high altitude, the temperature varies from 0°C to 16°C. in the Andes ranges.

Air Pressure And Winds: Low pressure prevails, all the year, over the Equatorial region in northern part of the continent. So, the Trade Winds are blowing from the northeast and south-east of the equator to this Equatorial Low-Pressure Belt. North-west westerly wind blows throughout the year over the southern part of the continent.

Rainfall: The saying ‘rain follows the sun’ is true for South America. The Amazon basin over which the sun shines more or less directly throughout the year gets very heavy convectional rain throughout the year.

In summer, most northeast and south-east trade winds blowing from the Atlantic Ocean, being obstructed by the Andes give heavy rainfall of 200 cm. or more which decreases gradually from the Atlantic coast in the east to the Andes Mountains in the west.

But the western side of the Andes becomes South America. The Seasons of Rain. dry as it is a ‘Rain Shadow’ area. So, it is found that the Atacama Desert is located in northern Chile bordering the Pacific Ocean coast.

Again the most northwest westerlies blowing from the Pacific Ocean give heavy rainfall to, the southern parts of the western coast as it is obstructed by the Andes mountains. Therefore, the Patagonia Desert is found in southern Argentina to the east of the Andes mountains where another Rain-shadow region has formed.

Climatic Regions Of South America: Based On The Variations In Temperature, Rainfall, Air pressure And Wind, South America May Be Divided Into The Following Climatic Regions.

1. The Equatorial Climate;
2. Tropical Savanna Climate;
3. Hot Tropical Climate;
4. Hot Tropical Desert Climate;
5. Medi-terranean Climate;
6. Temperate Desert Climate;
7. Warm Temperate Climate;
8. Cold Marine Climate and
9. Mountain Climate.

Climate Region Of South America:

Climatic Type/Region	Location	Climatic Characteristics
(1) The Equatorial Climate	Amazon and Orinoco basin near the Equator side by side in Brazil, Colombia, Venezuela, and southern Surinam.	(1)High Temperature (27’C) and humidity prevail throughout the year. Rainfall occurs about 200 cm/year.(2)Season change does not occur here (3)Convectional rain in the form of thunderstorms occurs more or less every day in the afternoon and there is no dry season at all.
(2) Tropical Savanna	Near the Orinoco river basin, and the Brazilian Highland, the grassland of Guinea.	(1)Summers are hot and Humid.(2)Winters are cool and dry.(3)Most of the rainfall occurs during summer.
(3) Hot Tropical Climate	Eastern Brazil	(1)Rainfall occurs In the summer.(2)Rainfall occurs due to moist trade winds from the east.(3)Summers are hot and humid.(4)Winters are cool and dry.
(4) Hot Tropical Desert	Atacama desert on the western part of the continent, Southern Peru, and northern Chile.	(1) The region is extremely hot and practically rainless. (2)Summers are very hot and winters are quite cold. (3)It is the world’s driest region.
(5) Mediterranean Climate	The southern part of the Atacama desert is located in Central Chile.	(1)Warm dry summers.(2)Mild wet winters. (3)Westerlies bring rain in winter. (4)The trades blowing over the land in summer fail to bring any moisture as well as rain.
(6)Temperate Desert	Desert regions of Patagonia in southern Argentina.	(1) Warm summer, (2) Cold winter,(3)Located in the rainshadow region of the Andes and receives only 13-15 cm. of rain annually. (4)It is called a temperate desert as it lies south of 40 latitudes.
(7)Warm Temperate (grass-land)Climate	South of the Tropical    region In north-eastern Argentina and Uruguay	(1) Moderate climate. (2) Summers are quite hot. (3) Rainfall decreases and so does the temperature.
(8) Cold Marine climate	South Chile and coastal regions of south-east Brazil.	(1) Cool climate.(2) Heavy rainfall throughout the year.(3) Moist wind blowing from the Atlantic ocean.
(9) Mountain Climate	Mountain Climate prevails in the western part of the continent in the Andes mountain region.	(1) As the temperature decreases with increasing altitude, at higher altitudes cold climate prevails.(2) The top of the Andes mountain year. (3) In the foothills warm climate prevails.

Chapter 10 South America Natural Vegetation of South America

As in other parts of the world, climate especially rainfall influences the natural vegetation of South America to a great extent. According to the variation in temperature and rainfall, natural vegetation of South America may be broadly divided into nine vegetation belts.

These are as follows:

Equatorial Rain Forest or Selva: The hot and humid climate has favored the growth of equatorial rain forests in the Amazon Basin and in the coastal regions of Guyana, Venezuela, Guiana, Surinam, etc. which receives heavy rain throughout the year. These forests are known as ‘Selvas’.

The Selvas of the Amazon Basin are the largest and densest expanse of equatorial forests in the world. The trees are hard evergreen and broad-leaved. The trees are 40/50 metres tall forming thick canopy through which sunlight cannot penetrate inside. So the ground is always damp and full of undergrowth.

Creepers are also common including the giant woody creepers called ‘lianas’ hanging from the branches. Thousands of species of trees are scattered all over the forest. As a result, it is difficult to obtain timber or forest products from the selvas. The trees are valuable hardwood varieties, such as Mahogany, Ablus, and Rubber. Brazil nut, Rosewood etc.

Tropical Grasslands or Savanna: This region lies north and south of the Equator. The Plateau of Brazil lying to the south of the Equator and a large part of the Orinoco river valley lying on the north are occupied by Tropical Grassland or Savannas.

Here rainfall is less and there is a distinct dry season that occurs only in summer and can support tall coarse grass and some trees many of which are acacias. These grasslands are locally called ‘Llanos’ in the Orinoco Basin and ‘Campos’ in the Brazillian Highlands.

“Class 8 Geography South America notes, WBBSE syllabus”

Warm Temperate Forests or GranChaco: This type of vegetation region lies south of the Brazilian Highland, i.e. the Parana-Paraguay river basin (the lowlands of northern Argentina and Western Paraguay). This region is locally called the ‘Gran-chaco’, which means ‘Great hunting ground’.

This region has open forests of sub-tropical valuable hardwood deciduous trees and grasslands. The chief trees of this region are the ‘Quebracho’ tree meaning ‘axe breaker’ is an extremely hardwood variety and the ‘Parana pines’, a type of softwood in great demand for building purposes.

The Quebracho, which yields tannic acid which is of great use in the leather industry. The leaves of the ‘Yerba Mate’ bush are brewed to make a tea-like drink.

Temperate Grassland Or Pampas: An extremely temperate grassland locally called ‘Pampas’ is found in Uruguay and around Buenos Aires in the northeast of Argentina. This grassland with soft, short, and juicy grasses is an ideal pasture for rearing cattle and sheep.

Characteristics of the Temperate Grassland or Pampas:

1. The Pampas are vast grasslands.
2. The grasses of this region are shorter than Savanna grassland.
3. The grasses grow luxuriantly.
4. These grasslands provide the basis for the pastoral industry.
5. Parts of the grasslands have been cleared for cultivation.

Desert Vegetation: There are two types of deserts in South America-

1. The thin strip of hot desert in coastal Peru and northern Chile called the Atacama desert and
2. The temperate desert of Patagonia in southern Argentina. The desert of Patagonia in the southern0°Caribbean Seapart of South America is treeless with the scattered presence of the scrubs.

The Atacama desert is almost rainless, is practically 0° devoid of vegetation except for some cacti and prickly pear. Thorny bushes and scrub, however, grow in Patagonia.

Equatorial Rainforest or Selva Tropical Grasslands or Savanna Warm Temperate Forests or Granchaco Temperate Grasslands or Pampas Bushes Mountain Vegetation Mediterranean Vegetation Cool Temperate Forests Scanty Desert Vegetation.

Mediterranean Vegetation: In central Chile with its humid or wet winters and warm dry summers, warm evergreen trees and shrubs occur. The Mediterranean climate supports dwarf vegetation which has long roots, small and thick waxy leaves, and short stems so that water is not lost through transpiration during the summer drought.

Common trees are fig, walnut, chestnut, and acacia. Evergreen Laurel, cork oak. grow in wetter areas, while lavender and rosemary grow in drier areas. Fruits like Olives and grapes also grow well in this region.

Cool Temperate Forests: Mixed forests of temperate deciduous and coniferous trees occur in southern Chile where rain falls throughout the year. Valuable hardwood trees like oak, beech, ash, and elm grow everywhere.

Softwood coniferous trees like pine and fir grow where snowfall is common, Some of the important trees of these forests yield valuable timber.

Mountain Forests: Owing to variations in altitude, the Andes mountains have a variety of natural vegetation. So in the western part of the continent, different types of trees are found.

Evergreen tropical rainforests and grasslands are common at the foothills. A little higher, there is the deciduous forest and then mixed forest which with increasing altitudes passes into the coniferous forests and finally into the Alpine meadows. Above the meadows occurs perpetual snow.

Little or No Vegetation: Atacama desert in northern Chile is treeless and dotted with thorny shrubs and bushes.

Chapter 10 South America The Selvas Evergreen Forest:

The Selvas of the Amazon basin are the largest and densest expanse of evergreen equatorial rainforests in the world. The forest lies on both sides of the equator covering mainly the major portion of the Amazon basin.

It covers Brazil (60%), Peru (13%), Colombia (10%), and parts of Venezuela, Bolivia, Guyana, Surinam, and French Guiana. It covers an area of about 5.5 million square kilometers.

The hot and humid climate has favored the growth of the equatorial rainforest in the Amazon basin which receives heavy rain throughout the year. The annual average temperature varies from 25° 28°C and the annual average rainfall is about 250 300 cm. A few places rainfall exceeds 1000 cm.

Thus the trees are hard, evergreen, and broad-leaved. This region is, therefore, called as “The Equatorial Evergreen Rain Forest’. Though it is a region of bright sunshine the region abounds in dense, lush green and luxuriant vegetation throughout the year. As the trees have grown closely spaced trees form a common canopy or crown.

No wonder the sunrays are often fail to peep through the thick foliage of trees in these forests to reach the ground. It is the trees that have to view with one another to reach out to the sun, and hence they grow very tall (some trees are 40 – 45 meters). So, the region is known as the “Region of twilight”.

Over a small area hundreds of different species of trees grow side by side. Therefore, the trees do not occur in pure stands. These forests are known for valuable hardwoods like mahogany, ebony, rubber, rosewood, ironwood, green heart, ivory wood, Brazil nut, and balsa (a very light wood).

The trees are of different heights. The branches of the taller trees are so thickly intertwined that sunlight cannot pass through the roof or canopy of leaves and branches. Creepers climb up the trees weaving a maze as it were and there is a dense undergrowth. Thousands of species of trees are scattered all over the forest.

As a result, it is difficult to obtain timber or forest products from the Selvas. Apart from the oceans, these forests are our largest source of atmospheric oxygen. It supplies about 20% of the earth’s oxygen and is termed the “lungs of the world”.

These evergreen forests are known for beautiful birds and butterflies. They occur in all sizes and in bright colors of every hue. The region overflows with insects and worms too. There are numerous termites, mosquitoes, spiders, ticks, driver ants, and tsetse flies.

Among the tree animals, there are monkeys, known for their wits and acrobatics. Apes, the closest cousins of human beings, are also found here. Puma and Jaguar of the Amazon valley are tiger-like animals that dwell upon trees. They mostly hunt monkeys for their food. Sloths, flying foxes, (bats), tree lizards, tree frogs, and flying squirrels are the other tree dwellers.

The Anaconda is the longest python that dwells here. It girdles its prey suffocating it to death. The forest rivers are full of a wide variety of fishes along with crocodiles and turtles. In the rivers, there are also found alligators and carnivorous Piranha fish.

Ten percent of the world’s total leaving species is found here. 25 lakh insects and four lakh species of trees exist here.

This region is very thinly populated because the weather is unhealthy. The density of the population in the Amazon basin is about two (2) persons/square kilometer. Primitive economic activity still prevails in a large part of the Amazon basin.

There are some groups of people still living deep inside the jungle. Though there is an amazing variety of valuable trees in the Selvas, lumbering is not well developed.

This is mainly because-

1. Thousands of species of trees are scattered all over the forest. So the same type of trees is hardly found close together. As a result, it is difficult to obtain timber/lumber from the selvas.
2. Most of the trees are very hard and difficult to saw.
3. After sawing, it is difficult to bring down the tree since the upper boughs of other trees are interlaced, and lianas twine round them.
4. The trunk is too heavy to be dragged upto the river over the soft forest floor. In the presence of these difficulties, lumbering is not developed in the Selva region.

Chapter 10 South America The Pampas Region

The grassland of Pampas in Argentina represents one of the great wheatlands and battlefield of the world. This is the most prosperous region of Argentina. The word ‘Pampas’ is derived from the spanish word ‘Pampa’ which means ‘extensive open plain land’.

An extensive grassland surrounding Buenos Aires in a semi-circle or like a crescent moon, to the northeast of Argentina, is called the ‘Pampas’.

Location: The region lies in the La-Plata basin. This region occupies one-fourth of Argentina and most of Uruguay and it also includes a small part of southern Brazil. It extends from 30°S to 40°S latitudes and 54° west to 65° west longitude between the Andes and the Atlantic.

Boundary The Pampas region is bounded on the north by uninhabited Gran Chaco, on the south by the Patagonia desert, on the west by the foothills of the eastern slopes of the Andes, and on the east by the Atlantic.

Physiography: The Pampas is a flat lowland sloping gently towards the Atlantic. It is formed by the silts, sands, clay, and loess soils deposited by the river and wind. Silts are very much fertile and in some places more than 150 meters thick.

There are a few hills because of which the plain appears to be rolling. There are two hills -Sierra del Tandil and De la Ventana (1300 m) in the Province of Buenos Aires. These are actually, the extended parts of the Brazilian Highlands. The region is higher in the western margin (about 450 m.) and it is only 20 meters in the east.

Rivers: The important rivers of the region are Uruguay (1593 km) and the Parana (4880 km). They have joined with each other near the north of Argentina’s capital Buenos Airesas La-plata estuary to fall into the Atlantic Ocean. The tributary of the Parana in this region is the Salado.

“WBBSE Class 8 Chapter 10 Geography, South America solutions”

Two other rivers are Colorado and Negro in the south. Following the slope, they all flow into the Atlantic. The Paraguay river is also a tributary of the Parana river.

Climate: The climate of this region is warm temperate type. Due to the close proximity with the ocean, the climate is comfortable here. The average summer temperature (In January) varies between 20°C to 26°C and in winter (In July) temperature varies between 8°C to 12°C. Annual rainfall varies between 50-100 cm. The rainfall increases from west to east.

Frost is common in winter. In summer, a strong cold wind called the ‘Pampero’ blows one the Pampas from the southwest. This is often welcomed since it not only towers the temperature but also causes rain that refreshes the pastures.

Natural Vegetation: The Pampas is a Typical temperate grassland supporting hardly any tree. The grass, though shorter than the Savanna grass, is softer and juicier. As the rainfall is more in the eastern part of the region the grasses are tall.

The original Pampa grass is now being replaced by other European grasses like Alfalfa. A few trees like Eucalyptus grow on the hills of the east-central part of this region. A few trees are also found mainly along the rivers. At present, most of the grassland has been destroyed for agricultural purposes.

Irrigation: Due to the insufficient river flows over the Pampas, irrigation is needed. So, wells are dug and wind pumps are used to tap underground water for irrigating the agricultural lands.

Agriculture: The western part of the Pampas is a semi-desert. This region called the dry Pampas is thus mostly barren, but the humid Pampas in the east is the chief source of the agricultural wealth of Argentina. It is one of the richest livestock cum crop-producing land of the world. Pampas region is famous for wheat cultivation.

1. Mild cool climate,
2. Rainfall,
3. Rolling plains,
4. Fertile soils favour the cultivation of wheat.

Here Wheat is the leading crop. 60% is exported to other countries. So the Pampas is known as the “Wheat basket of South America”. Maize, flax, cotton, linseed, barley, sugarcane, oats, and soybean are also cultivated. Fruits (apricots, apples, cherries, pears, and peaches) and vegetables are grown especially around the big cities.

Other fodder crops cultivated are rye and other oilseeds. Different types of agricultural products are grown here in abundance. So the Pampas region is called “The Granary of South America”.

Animal Rearing: The Pampas region is the grazing ground for Argentina’s famous cattle. Sheep are also reared here. Cattle are raised on the tall grasses in the east and sheep are raised in the west and southern parts of drier and cool climates. A rench where 20000 cattle and sheep are raised, is locally called ‘Estancia’ each of which covers 4000 acres of land.

They are raised for meat, hides, wool, milk, and milk products (Powdered milk, butter, cheese, cream etc.) which are expected in large quantities to the foreign countries Argentinas beef is prized throughout the world for its superior quality and flavor, Argentina is the largest exporter of beef in the world.

Beef extract, and ground bones are also produced here. Buenos Aires, La Plata is noted for animal products cordoba located on the foothills of the Andes is a famous dairy center. Dairy farming is also practiced around large cities meet the huge daily demands for dairy products in the local markets.

Merino sheep are reared in the drier south and southwest and the English breeds elsewhere. Thus large amounts of mutton and wool are exported to Europe.

Mineral resource: The Pampas region is not rich in mineral resources. Little copper ore and tungsten are available on the hills in the north. A little quantity of gold is also available on the bank of the river Salado.

Transportation: The lowlands of the pampas are well served by a network of roads and railway lines. There is also a transcontinental railway line from Buenos Aires to Valparaiso in chile passing through the Andes mountains. Export-import.

Industry: The pampas region is poor in mineral resources. As a result, no large-scale and metallurgical industries have been developed here. Industrial development has taken place based on agricultural and animal raw materials.

Important industrial activities are-

1. Dairy farming,
2. Meatpacking,
3. Leather,
4. Wool and other consumer goods, manufacturing.Important industrial centers are Buenos Aires, Laplata, Cordoba, and Rosario other industrial activities of these centers,
5. Engineering,
6. Chemical,
7. Cotton textile,
8. Food processing,
9. Oil refinery etc.

Population: Pampas Region is not well populated. The vast grasslands are usually used as pastures and farmlands. Gauchos, the cowboys who are engaged to look after the cattle, are actually pastoral nomads. But the cities are well-populated, Such as,

1. Buenas Aires,
2. Bahia Blanca,
3. La-Plata,
4. Rosario and
5. Cordoba.

“WBBSE Geography Class 8 South America, Chapter 10 key concepts”

Buenos Aires: This is the capital, principal city, and chief port of Argentina. This is a million city (12.05 million in 2001), and the second largest city of South America. It is situated at the estuary of La Plata and an important industrial as well as trading center of Argentina. This is known as the ‘Paris of South America’.

Bahia Blanca: It is situated on the Atlantic Coast and chief seaport of Argentina.

La-Plate: La Plata is a modern city cum industrial center.

Rosario: It is situated on the Parana, a natural link between the Gran Chaco and the Pampas. It is a rail and road hub and on important river port cum industrial center.

Cordobadairy center: Cordoba is also a fast-growing industrial cum tourist center and famous dairy center.

WBBSE Notes For 8 Class Middle School Geography

• Chapter 1 Interior Of The Earth Notes
• Chapter 2 Unstable Earth Notes
• Chapter 3 Rocks Notes
• Chapter 4 Pressure Belts And Winds Notes
• Chapter 5 Cloud And Rain Notes
• Chapter 6 Climatic Regions Notes

• Chapter 7 Human Activities And Environmental Degradation Notes
• Chapter 8 Some Neighbouring Countries Of India Notes
• Chapter 9 North America Notes
• Chapter 10 South America Notes
• Chapter 11 Oceania Notes

Chapter 4 Pressure Belts And Winds

Pressure Belts And Winds

The atmosphere or the sphere of the air envelope the layers of invisible gases that surrounds the earth. It is held to the earth by the force of gravity and rotates with it. It represents the gaseous realm of the earth. It is mobile/ elastic, both compressible and expansible. The atmosphere is a vital part of human existence on earth.

Air Pressure: The atmosphere is composed of air and other particles like water vapour and other materials. Though the air is very light, it has weight. It also exerts pressure on the earth’s surface. The weight of air on the unit area of the earth is called ‘air pressure or atmospheric pressure’.

Read and Learn all WBBSE Notes For 8 Class Middle School Geography

It was Toricelli, a disciple of Galileo, who first practically measured air pressure in 1643. The atmosphere exerts a pressure of more than kg/sq. cm (1-03 kg/cm or 6-68 kg/inch) at sea level or 760 mm/cm or 76 cm or 1013-25 millibars. Air exerts pressure equally on all sides, we are supported by an equal pressure of air on all sides of our body. So, we do not feel this pressure.

“WBBSE Class 8 Geography Chapter 4 notes, Pressure Belts and Winds”

There are two types of air pressure—(1)High pressure and (2) Low pressure.

More air molecules present in a definite volume of air develop high pressure and fewer air molecules present in that airmass form low pressure. So, an air of high pressure is dense and that of the low pressure is thin. More than 1013-25 millibar pressure is called ‘High pressure’ and less than 986 millibar pressure is called ‘tow pressure’.

Variation in Air Pressure: Air pressure is not uniform over the surface of the earth but varies from place to place for the following conditions:

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• Variation of Temperature,
• Altitude from the sea level,
• Rotation of the earth,
• Presence of water vapour,
• Depth of the atmosphere.

1. Variation of Temperature: Warm air is lighter and pressure is less. So, it goes up forming a low-pressure zone. We call this low pressure because the air is less dense, and exerts low pressure. On the other hand, cold air which is heavier and denser exerts more pressure and settles down on the ground forming a high-pressure zone.
2. Altitude from the sea level: Air is highly compressible. So, it is denser in the lower parts of the atmosphere and lighter with an increase of altitude. This air pressure will be higher over a lowland area and lower over a higher mountainous area.
3. Rotation of the earth: The rotation of the earth also causes variation in the air pressure. The air is thin around the sub-polar areas because of the rotation of the earth swings the bulk of the air towards the Equator.
4. Water vapour: Moist air is lighter than the air without it. Dry air is heavier than moist air because it contains more nitrogen and oxygen than humid air. This is why air pressure is low during the rainy season and in winter air pressure is high.
5. Depth: In the lower layer of the atmosphere is denser than at the higher level and therefore the pressure is high but as we go higher up the pressure of the air decreases because fewer air molecules are present in that airmass.

Chapter 4 Pressure Belts And Winds: Air Pressure Belts

 

There exists a definite pattern of alternate high and low-pressure belts over the earth’s surface. A ‘Pressure Belt, is a zone of uniform width, around the earth, extending in an East-West direction parallel to the lines of Latitude. On the earth’s surface, there are in all seven pressure belts. Four belts of high-pressure separate three low-pressure belts.

1. The Equatorial Low-Pressure Belt: The equatorial belt of low pressure extends from the Equator to 5°N and 5°S latitudes. This belt has been formed due to

• Vertical sun rays fall on this region throughout the year as such, air is warm and light all year round. The air expands and becomes lighter, rises upwards as convection currents and finally ascends to form this low-pressure belt,
• Presence of water vapour is more in this region. So water vapour further helps in lowering the air pressure there,
• Due to the rotation of the earth bulk of the air above this region swings towards the north and south, as such, air becomes, thin and formed low pressure.

Equatorial calm or Doldrums: The belt of equatorial low pressure is termed as ‘Doldrurns’-because there is no horizontal movement of air or wind. Air is continuous by ascending from this region. Thus, in the equatorial region, ‘Calm’ conditions prevail and the region is called Equatorial ‘calm or ‘Doldrums’ which means ‘to Stagnate’.

 

2. And 3. Sub-tropical High-Pressure Belts: Two sub-tropical high-pressure belts are formed near the tropics (Tropic of Cancer and Tropic- of Capricorn} and extend between 30° – 35° North and South latitudes.

The causes behind the formation of these two high-pressure belts are:

1. The warm and moist air over the Equator rises, cools and spreads towards the north pole and the south pole. On reaching latitudes 30° North and 30° South the air becomes cool, dense and heavy. Consequently, it descends to form these high-pressure belts. These are regions of calm with light winds and quiet, stable weather conditions,
2. Due to the rotation of the earth, cold air from the polar region swings towards this region.

Sub-tropical calm: Horse Latitude— in sub-tropical high-pressure belts, the air is calm. So, these high-pressure belts are known as the sub-tropical calms’, it is also frequently known as Horse latitudes’, it is explained that, in the colonial days of sailing ships carrying horses used to sail from Europe to the West Indies.

On the way, over these regions, because of the absence of horizontal wind, ships had to unload cargo. So, many horses were thrown into the Atlantic Ocean to make the ships lighter to conserve drinking water. Since then, the region between ^ ~~35° (25°—35°) parallels in both hemispheres are frequently called “Horse Latitudes’.

“Class 8 WBBSE Geography Chapter 4 notes, Pressure Belts and Winds study material”

4. And 5. The Sub-Polar Low-Pressure Belts over the Arctic or Antarctic circle: Two subpolar low-pressure belts are located between 60°—65° North and South latitudes.

In these belts low pressure develops because—

1. The earth’s rotation swings the bulk of the air from these areas towards the Equator
2. Cold winds of the polar highs expand when they reach these two regions and
3. Warm and light westerlies blow above cold and heavy polar winds. So, in the sub-polar region, the density of air is less therefore, pressure is also low.

6. And 7. Polar High-Pressure Belts around North Pole and South Pole: Two high-pressure belts are found around the North Pole and South Pole because—

1. This is a region of permanently low temperature, as such, the pressure of the air is high,
2. Evaporation is less, so water vapour is almost absent and
3. The air that rises above the sub-polar regions swings and descends over these areas.

Pressure cells: Variations in the distribution of land and water cause variations in air temperature and pressure over land and water even in the same latitudes. For this, there is no continuous belt of pressure all over the world.

The discontinuity of these bands of air temperature and pressure over the same latitudes forms isolated small cells of air pressure.

These concentric pressure centres or cell are known as ‘Pressure Cells’. in the northern hemisphere is greater variation due to the location of continents and oceans. Therefore, air pressure cells are seen more often over the northern hemisphere.

Shifting of Pressure Belts and Planetary Winds: The pressure belts of the world are formed mainly because of the heat of the sun. So, the pressure belts shift with the apparent annual movement of the sun.

Owing to the revolution of the earth, there is an apparent movement of the sun from the northern hemisphere to the southern hemisphere with the movement of the sun, the pressure belts shift northward in the summer and southward in winter.

In June when the sub-solar point (vertical position of the sun) lies over the ‘Tropic of Cancer (231/2° North), it is summer in the Northern Hemisphere, as such, the pressure belts are shifted by 5° to 10° north of their normal positions.

“WBBSE Class 8 Geography Chapter 4, Pressure Belts and Winds study guide”

Similarly, in December, when the sun lies over the ‘Tropic of Capricorn (23%° South), it is summer in the Southern Hemisphere and the pressure belts shift by 5° to 10° south of their average positions.

With the shifting of the pressure belts, the wind belts also, shift their position which causes the change of their direction and velocity of flow. The swing of this whole wind system has a great impact on the climate of the region lying between 30° and 45° parallels of latitude in both hemispheres.

These regions come under the ‘Trade winds’ which give rain to the eastern coasts of the southern part of Argentina, and Sudan but do not give any rain in the western margins (e.g. Mediterranean lands, southern chile) as they are off short there.

In winter, these regions come under the influence of the westerlies and receive sufficient rainfall. So, it is rightly said that rain follows the sun as the entire system of pressure belts and planetary winds follow the sun.

 

Chapter 4 Pressure Belts And Winds: Winds

 

The unequal distribution of heat on the earth’s surface causes the formation of high and low-pressure belts over the earth. Lighter air ascends to form the low-pressure belts while heavier air descends to form high-pressure belts.

Air current: The vertical movement of air over the earth’s surface is called ‘air current’.

What is wind: The horizontal movement of air from high-pressure to low-pressure areas along the earth’s surface is called ‘wind’.

 

Centrifugal force: The fictional force that acting, moves or tends to move away from a centre to an outward side is called ‘centrifugal force’.

“WBBSE Class 8 Pressure Belts and Winds notes, Geography Chapter 4”

Coriolis Force: It was named after the French mathematician Gaspard de Coriolis, who first described it inl835. A force resulting from the rotation of the earth deflects moving bodies to the right in the Northern Hemisphere and to the left in the Southern Hemisphere. This affects winds, ocean currents and humans.

Ferrel’s Law: The winds are deflected from their true gradient course due to the earth’s rotation. U.S. meteorologist William Ferrel following Coriolis force formulated a law in 1859 to deduce the direction of winds in the northern and southern hemispheres. It is known as Ferrel’s Law.

According to Ferrel’s law: If we stand with our faces in the direction in which the wind northern hemisphere southern hemisphere is blowing from high pressure to Westerlies are deflected to their right as South-West Westerlies.

“Class 8 WBBSE Geography Chapter 4, Pressure Belts and Winds easy explanation”

In the southern hemisphere, Trade winds are deflected in their left as South-East Trade Winds while westerlies become North-West Westerlies.

 

 

Buys Ballot’s Law: A Dutch meteorologist not only Christoph Buys Ballot postulated a law in 1857 which relates the wind direction to the position of air pressure areas.

According to this law, “If an observer in the northern hemisphere stands with his backs to the wind atmospheric pressure will be lower on his left hand, in the southern hemisphere pressure is lower on his right. This is the result of Coriolis’s force on the earth.

Classification of winds: Winds can be classified into four major types:

1. Planetary winds,
2. Periodical winds,
3. Local winds and
4. Sudden or Irregular winds.

1. Planetary or Permanent Winds: In the surface of the earth, certain winds blow constantly in a particular direction from the high-pressure belt to the low-pressure belt throughout the year. These winds are called ‘Prevailing’ or permanent or Planetary or Constant winds. These winds are of three types—

• Trade winds,
• Westerlies, and
• Polar winds.

 

Air Pressure Belt

• An account of Trade Winds: The winds that blow regularly in a definite direction from the tropical high-pressure belts (30°—35° North and South latitudes) to the equatorial low-pressure belt in the both hemisphere are called ‘Trade Winds’. The name ‘trade’ is derived from the German word ‘trade’ which means ‘Track’. These winds blow in the same direction in a definite track, as such, these winds are called ‘Trade Winds’.

These winds were also helpful to the early traders who depended on the wind when sailing in the seas; hence, the name ‘Trade Winds’. In the northern hemisphere, their direction is north-easterly and in the southern hemisphere, south-easterly. As the trade winds come from the east in both the hemispheres, they are also called the ‘Easterlies’.

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Origin of the Trade Winds: The Trade Winds are originated from a pressure gradient (difference in pressure) of the Sub-Tropical High-Pressure Belt to the Equatorial Belt of Low Pressure.

Types of Trade Winds: Trade Winds are of two types—

• Worth-East Traoe Wind
• South-East Trade Wind.

 

1. Worth-East Trade Wind: In the Northern Hemisphere, winds blowing towards the Equator, are deflected to the right and according to Ferrel’s Law become ‘Worth-East irade Winds.
2. South-East Trade Wind: Southern Hemisphere deflection of the wind is towards the left and the winds become ‘South-East Trade Winds’.

ITCZ or Inter-Tropical Convergence zone: A zone of low atmospheric pressure near and more or less parallel to the equator (5° North and 5° South), where the North-East, and SouthEast. Trade winds meet, being thus associated with the Doldsums is called ‘I.T.C.Z.’

The velocity of Trade Winds: In the Northern Hemisphere as the landmasses are the more, the velocity of the North-East Trade Wind is about 16 km/ hour. While in the Southern Hemisphere, water bodies are more, as such, the velocity of the South-East Trade Wind is a little more, about 22-23 km/hour.

Influence of Trade Winds: Since these Trade Winds blow from the cooler sub-tropical latitudes to the warmer tropics, they have a great capacity for holding moisture. On their way, while crossing the open oceans, they pick up moisture and give heavy rainfall to only the eastern parts of continents within the tropics.

“WBBSE Class 8 Geography Chapter 4, Pressure Belts and Winds important questions”

While reaching the western part of the continents they get dry and give no rain. It is one of the reasons that the world’s great deserts like California, Sahara, Thar (India), Atacama (Peru and Chile in South America), Kalahari (In Africa) and the West Australian Desert have been formed.

2. Westerlies: The Winds that blow from the Sub-tropical High-Pressure belts towards the Subpolar Law Pressure belts in both hemispheres are called ‘Westerlies’. In the Northern Hemisphere, their direction is south-westerly and in the Southern Hemispheres, it is north-westerly. As they blow from the west in both the hemispheres, they are called the ‘Westerlies’.

Origin of the Westerlies: Due to the rotation of the earth low pressure develops over the Arctic and Antarctic Circles, while there is relatively high pressure over the Tropic of Cancer and Tropic of Capricorn. So, winds move from these high to the low-pressure belt as Westerlies.

Types of the Westerlies: The Westerlies are of two types—

1. South-West Westerly and
2. North-West Westerly.

Under the effect of Coriolis Force, westerlies are deflected. Following Ferrel’s Law, they become South-West Westerly in the Northern Hemisphere and North-West Westerly in the Southern Hemisphere.

Roaring Forties: In the southern hemisphere between 35° to 60° South latitudes westerlies are best developed due to the vast expanse of oceans and the absence of extensive landmasses. Westerlies of this zone are/therefore blow uninterruptedly with much greater force. It is called ‘Brave Westerlies’. When brave westerlies blow along 40° South depending on violent sounds made by these brave westerlies are called ‘Roaring Forties’.

Furious Fifties: When the brave westerlies blow along 50° South parallels of latitude then it is called ‘Furious Fifties’.

Screeching/Shrieking Sixties: When the brave westerlies blow along the 60° South parallels of latitude, then it is called ‘Screeching or Shrieking Sixties’.

Influence of Westerlies:

1. These winds are on-shore winds on the western coasts of continents and bring much precipitation. But the eastern parts remain comparatively dry.
   These winds are variable in strength and direction. Cyclones and anticyclones produce uncertain weather. The weather is changing due to clouds, fog, gales and snowfall.
2. The westerlies blow uninterruptedly with much greater force and regularly throughout the year. These are best developed in the southern hemisphere due to the large expanse of oceans, and the absence of extensive landmasses. Here these are termed as “brave westerlies” or “brave Westwinds”.The latitudes in which westerlies blow are called, “Roaring Forties, “Furious Fifties”, and “Shrieking Sixties”. These stormy violent winds are dangerous for shipping.
3. Westerlies bring winter rainfall in many parts of the Mediterranean region. It is to be noted that westerlies bring rainfall to the western coasts of the continent of temperate lands.

3. Polar Winds: Polar winds blow from Polar Highs of the Arctic and Antarctic to the sub-polar lows of the Arctic circle and Antarctic circle respectively. As these winds originate from the poles, they are known as ‘polar winds’.

The velocity of Polar Wind: Polar winds are very much weak, especially, in the northern hemisphere. In the southern hemisphere, it is relatively strong.

The latitudinal extent of Polar Winds: Blowing between 60° to 85° Parallels of latitudes.

Effects of Polar Winds:

1. Polar winds are very cold and dry as they blow from the poles and from the coldest parts to a warmer region.
2. They are extremely cold and are responsible for a bitterly cold climate.
3. They blow in high velocity and bring about cyclones, and blizzards.
   In the South Pole these stormy winds have greater velocity and intensity of force Sometimes, a situation of anticyclones prevails there.

 

Chapter 4 Pressure Belts And Winds: Periodic Winds

 

The winds which blow from time to time or in a certain period (season) of a year, are called. ‘Periodical winds’ viz.

1. Sea Breeze,
2. Land Breeze,
3. Monsoon-Land and sea breezes are a periodic type of winds and consist of a conventional system of winds.

These are caused by the differential heating of land and sea. These affect a narrow strip along the coast. These are also known as “monsoons on a smaller scale”.

1. Sea Breeze: During the daytime, the land gets rapidly heated up than the sea. The warm air rises to form a low pressure locally on land.

The sea being cooler develops a high pressure. So, a cool sea breeze blows from the sea to land. Thus, the winds complete a convection cycle.

Effects:

1. It brings cool and fresh air from the sea.
2.  Sea Breeze moderates the temperature of the coastal areas resulting in an equitable or maritime climate,
3. Its influence does not exceed 30 km from the coast.

2. Land Breeze: During the night the land becomes cooler than the sea. The cold and heavy air produces a local high pressure on land. The sea remains comparatively warmer with a low pressure. Therefore, a land breeze blows from land to sea. These are effective under calm, cloudless sky.

Effects:

1. The fishermen take advantage of the outgoing land breeze and sail out within the morning. They return with the incoming sea breeze in the evening.
2. The return current of warm air from the sea has a moderating effect on the temperature.

 

 

3. Monsoon Winds: The term ‘Monsoon’ is derived from an Arabic word meaning ‘season’. The winds that blow with the change of seasons is called ‘monsoon winds’. Thus monsoon winds are seasonal winds.

The term was first used for the monsoon winds blowing over the Arabian sea. In this wind system, there is a reversal of wind direction according to seasons. In summer, monsoons blow from sea to land and in winter monsoons blow from land to sea.

Origin: Monsoons are land and sea breezes on a large scale. These winds have a thermal origin. These are caused by the differentia! heating and cooling of land and water. The chain of events is from temperature through pressure and winds to rainfall.

“Class 8 Geography Pressure Belts and Winds notes, WBBSE syllabus”

In summer, the land gets more heated than the sea resulting in a low pressure on the land masses and a high pressure overseas. The winds blow from sea to land. Land breeze and sea breeze follow a daily rhythm over a small coastal areas.

Necessary conditions: The monsoons are developed under the following conditions.

1. The pressure of a large landmass (Continent).
2. The presence of a large ocean.
3. Long coastline.
4. Seasonal extremes of the temperature of land and water.

Areas: Monsoon winds mostly blow in tropical areas. The Himalayas separate these areas into two parts.

1. East Asian Monsoons blowing over China, Japan and Indo-China.
2. Indian Monsoons of India, Pakistan, Bangladesh and Myanmar.

Pressure Belt On Earth

Summer Monsoons: In summer the central, the central parts of landmasses like Asia get more heated than the seas and oceans around them. Therefore, low pressure develops over the land. As a result winds blow from the seas to land in summer. These winds are called the summer monsoons’. They bring heavy rain as they come from the seas.

Winter Monsoons: During winter, high pressure develops over the land masses and low pressure over the seas and oceans. Therefore, the winds start blowing from the landmasses towards the seas and oceans. These winds are called ‘winter monsoons’. These are dry winds for central part of Asia, particularly for most of India.

 

Periodical Local Winds:

Anabatic and Catabatic Wind: These are local slope winds. These winds are periodic winds which blow along the valley slopes. These are also diurnal in character. Mountain winds blow down the slopes at night while the valley winds ascend the slopes during the day.

Anabatic or Valley Wind: A local wind that blows upslope during the day in mountain areas is called ‘anabatic’ or ‘valley wind’. The air above the valley slopes is heated to a greater extent than air at the same height above the centre of the valley.

“WBBSE Class 8 Chapter 4 Geography, Pressure Belts and Winds solutions”

Air thus rises up from the slopes and feeds an upper return current. As the winds rise, these are condensed and give heavy rain. These winds tend to moderate the temperature.

Catabatic or Mountain Wind: A cold downslope wind caused by the gravitational movement of cold dense air near the Earth’s surface is called ‘Catabatic’ ‘mountain wind’ ‘canyon wind’, or ‘gravity wind’.

During the night the winds at the mountain tops become cold and dense due to rapid radiation. This cold air, under, the influence of gravity, descends down the valley slopes. It is also known as ‘nir drainage’. Due to these, the front occurs in the lower parts of the valleys. Therefore, ‘citrus orchards’ in California and coffee ‘agendas’ in Brazil are grown on mountain or hill slopes.

 

Chapter 4 Pressure Belts And Winds: Local Winds

Due to local differences in heating and cooling on account of the configuration of land or distribution of land and water, certain winds are caused which are to be found even in the generalised wind belts of the world. These are called ‘Local Winds’. Most of the local winds are developed by local depression.

They affect only limited areas and blow for a short period. Some of the local winds are as follows:

1. Loo: Loo is a hot dry and dusty wind. It blows in the northwestern part of India. It desiccates and dries up surface moisture. It blows in the month of May and June over the northern plains, especially in U.P. in India.
2. Andhi: During summer months very dry sand storms are very frequent in the northwestern part (Rajasthan) of India. These dust storms are locally known as ‘Andlll’ because it overcasts the sky with dust and cloud.
3. Nor’wester’s (Kalbaishakhi): During the afternoon of summer months (Chaitra- BaishakK) life” thunderstorms along with rainfall mainly occur in West Bengal, it is known as ‘Kalbaishakhi’ 0ne Rainshadow region of India is the Deccan plateau or the northern part of the Meghalaya Plateau (Leeward side of the slope).
4. Chinook: Chinook winds are experienced on the leeward eastern slope of the Rockies and Prairies in the U.S.A. and Canada. It causes snow to melt and disappear very quickly for which Is known ns Snow-eater’, It thus makes pasture available. This raises the temperature of the area by 15C to 20C. In a couple of hours.
5. Fohn: Fohn Is a warm dry wind blowing across the Alps down the valley in Switzerland in spring.

Effects of Fohn:

1. It melts snow rapidly and hastens the growth of crops,
2. These winds make the winters mild.
3. These help animal grazing by removing snow from pastures.
4. The winds help in. the early ripening of grapes.

6. Bora: It is a cold and dry wind. It blows during winter along the Adriatic coast of northern Italy. It is a northern or north-easterly wind. It occurs when the atmosphere remains high over central Europe and low pressure over the Mediterranean. It pr generally cold and dry weather. But, sometimes, cause heavy cloud, rain and snow.

7. Mistral: A cold dry and usually strong northernly or north-westerly wind expo in South France, especially in the Rhone delta area is called ‘mistral’. It occurs when high pressure over France and low pressure over the Mediterranean (i.e. mainly in It is a forceful wind with a speed of 60 to 130 km./hour. It brings down temperature freezing point.

8. Simoom/Simoon: Simoon is a hot, dry and painful wind of summer in the Arabian and Saharan deserts. It carries many sand particles and thus reduces visibility and often resulting in localized dust storms or sandstorms.

9. Sirocco: A southernly wind that blov/s from North Africa across the Mediterranean sea to Sicily and south Italy, proceeding a depression moving eastward through the Mediterranean basin is called ‘Sirocco’, it is very dry and hot on the North African coast as a result of bavin blown off the desert, but after crossing the sea and picking up moisture it is often very hum! and enervating When it reaches Sicily and Italy.

10. Khamsin: A hot dry southernly wind that blov/s across Egypt and the South-East Mediterranean area from the Sahara is known as ‘Khamsin’ in Egypt. It proceeds depression moving eastwards through the Mediterranean Basin and occurs for a period of about 50 days between April and June, (the name Khamsin being the Arabic v/ord for fifty). Dust storms are frequent, but in areas where the wind has not crossed a stretch of ocean, the air may be quite humid.

11. Harmattan: Harmattan is a strong, hot, very dry and dusty wind blowing from a north-easterly or sometimes easterly direction over north-west Africa, from the Sahara to the north-west African coast, the southern limit averaging 5°N in January (mid-winter) and 12 N in July. Heavily dust-laden and parching in the interior, it helps to evaporate the high humidity of the Guinea coast, and thus seems a relatively cool and healthy wind in that area, hence its local name there ‘the Doctor.

12. Pampero: A type of cold wave or polar outbreak that occurs in parts of Argentina and Uruguay when very cold dry air is drawn in from the south or southwest behind an eastward moving depression. It commonly resembles a line squall with very dark clouds often augmented by dust blown up off fie- Pampas, and sometimes with rain, thunder and lightning.

 

Chapter 4 Pressure Belts And Winds: Variable Sudden Or Irregular Winds

 

Intense heating and cooling of land surface or water bodies, sometimes, develop severe low-pressure centre, depression or trough or centre of high pressure. On a place where the air pressure suddenly falls or rises within a short time. If causes strong winds to blow a great speed and changes or breaks in the wind system. Their direction, shape, extent and scope is uncertain.

These are known as ‘variable winds’ Their sudden movement and irregular nature cause them to he called ‘Sudden’ or irregular winds. Cyclones and anticyclones are examples of this type of wind.

“WBBSE Geography Class 8 Pressure Belts and Winds, Chapter 4 key concepts”

Cyclones: When the stormy whirlwind comes is spirally moving in towards a low pressure centre, it is some of the characteristics of the cyclone,

1. Cyclone develops due to the formation of an intense low-pressure centre.
2. A cyclone has a low pressure at the centre and high pressure on the surrounding sides.
3. The wind movement in a cyclone is anti-clockwise in the northern hemisphere and clockwise in the southern hemisphere.
4. It blows towards the centre of low pressure from all sides,
5. On reaching the centre of low pressure it moves upwards. short time.
6. In the structure of a cyclone, isobars from an oval or circular shape.
7. Rain falls at the centre of the cyclone.

 

Classification of Cyclones: Cyclones are divided into two types according to their formation and difference in their location.

1. Cyclones formed in the Tropical zone are called ‘Tropical Cyclones’ and
2. In the Temperate zone, the ‘Temperate Cyclones’.

Tropical Cyclone: Tropical cyclones are developed in the western margins of ocean and seas in the tropical region between 8° and 20* north and south latitudes.

The cyclones of the Tropics are thermal In origin and develop due to the local convection currents acquiring a whirling motion on account of the rotation of the earth. These develop at special seasons over the sea within the Tropics. The conditions most suited to their origin and development are

• Quiet air
• Highly saturated atmosphere and
• Great heat.

 

The following are some of the characteristics to the track of a tropical cyclone:

 

1. Between the Equator and 15° latitude, these storms turn towards the west with the trades.
2. Between 15° and 30° latitude the path is very uncertain. But these travel towards the north in the northern hemisphere and towards the south in the southern hemisphere.
3. As these cross 30° latitude they turn towards the east and their terrific energy declines.
4. tropical cyclones are usually small in size and they have a diameter of 100 to 500 km.
5. These strong winds exceeding 100 or 150 km/hour are common. Sometimes the velocity increases to 250 or 300 km/hour.
6. The centre of this cyclone has the lowest air pressure and it is called the ‘Eye of the cyclone’.
7. They are violent and very much destructive in nature. These cause heavy floods and huge destruction of life and property. Trees are uprooted, houses collapse, rail lines, roads and telecommunication lines are disrupted, the coastal parts are submerged.
8. Tropical cyclones are associated with dark cumulonimbus clouds and torrential rain accompanied by thunders and lightning.
   Parts of the East coast in India are badly affected by tropical cyclones in every year during late summer or autumn.

“WBBSE Class 8 Geography Chapter 4, Pressure Belts and Winds summary”

The chief areas of activity for tropical cyclones are the following:

1. West Indies and the coast of Florida. In that region, these are known as ‘Hurricanes’.
2. Philippine Islands, the coasts of China and Japan. These are known as ‘Typhoons’.
3. Bay of Bengal and the Arabian Sea, where these are known as ‘cyclones’.
4. Madagascar (Malagasy) and the coastal regions of East Africa.
5. North-east and North-western coasts of Australia.

Temperate cyclones: Temperate cyclones are common in the sub-polar low-pressure belt. They are found in the temperate region between 35 and 65 latitudes. These are most dominant over the North Atlantic Ocean and especially during the winter season. These cyclones are frontal in origin. They develop due to the meeting of warm tropical and cold polar airmass.

Characteristics Of Temperature Cyclones:

1. These Temperate cyclones are of frontal origin. There are six stages in the development of a temperate cyclone.
2. Temperate cyclones are much larger in size than of tropical cyclone and these have a diameter of 1000 to 2000 km.
   These are oval-shaped.
3. Wind velocity is comparatively moderate and in average it ranges between 30 and 50 km/hour.
4. These mostly originate in winter.
5. These are weaker than tropical cyclones.
6. Temperate cyclones are less destructive and less violent.
7. They bring rain and cloudy weather and last for a long period.

In India, temperate cyclones are experienced during January and February. They originate in the Mediterranean region and approach north-western part of India through Iraq, Iran and Pakistan. Punjab, Haryana, Uttar Pradesh and Uttarakhand receive rainfall and Jammu and Kashmir and Himachal Pradesh receive snowfall from these cyclones or depressions. The rainfall received in northwest India by temperate cyclones is very beneficial for the rabi crops.

“WBBSE Class 8 Geography Chapter 4 Pressure Belts and Winds, definitions and examples”

Pressure Belts And Planetary Winds

Anticyclones: An anticyclone is just the reverse of a cyclone. It is a wind blowing spirally outward from a high pressure centre. The general characteristics of an anti-cyclone and its structures are as follows:

1. An anti-cyclone lies between two cyclones and it has no definite direction,
2. The isobars are far apart more especially towards the centre. Variations of temperatures are also noticed.
3. The winds are light and slow. They never grow violent and at the centre there is calm with variable winds. Anticyclones at Northern and Southern hemisphere.
4. Often cold and heat waves accompany the anti-cyclones.
5. Within an anti-cyclone there are local rains,
6. It is extensive and its velocity ranges from 30 to 45 km/ hour.
7. Winds in an anti-cyclone circulate in clockwise direction in the northern hemisphere. While it is anti-clockwise in the southern hemisphere.
8.  Anti-cyclonic conditions present calm and clear weather with sunny conditions.

 

 

Difference between Cyclones and Anti-cyclones:

Cyclones	Anti-cyclones
(1) Cyclone has low pressure at the centre.	(1) Anti-cyclone has high pressure at the centre.
(2) It blows toward; the centre of low pressure from all sides.	(2) It blows in all directions from the centre.
(3)In the northern hemisphere it moves anti-clockwise, and in the southern hemisphere, it clockwise.	(3)In the northern hemisphere it blows clockwise, and in the southern hemisphere, it is anti-clockwise.
(4) On reaching the centre of low pressure it moves upwards.	(4)It moves downwards.
(5) It is strong and lasts for a short time.	(5)It Is not very strong and generally continues for a long time.
(6) Bain falls at the centre of cyclones.	(6)It does not produce rain, rather, it brings fair weather.
(7) Winds arc warm and ascending.	(7)Winds arc cold and descending.
(8)l here present rough and cloudy weather accompanied by thunder, lightning and heavy rain or snow.	(8)Antl-cyclonic conditions present calm and dear weather with sunny conditions.

 

 

 

 

 

WBBSE Notes For 8 Class Middle School Geography

Chapter 2 Unstable Earth

Unstable Earth:

1. Though the Earth apparently seems stable, it does not follow that it is fully stable. The earth’s crust has been undergoing changes for millions of years. The earth is unstable because it is regularly facing natural events like violent volcanic eruptions, earthquake tremors, shifting of plates, landslides, avalanches etc.
2. Though we cannot always feel this movement of the land on the surface of the earth, but the face of the earth is constantly shaped by these natural forces active above the surface of the earth and beneath it.

Read and Learn all WBBSE Notes For 8 Class Middle School Geography

• According to the ‘Continental Drift Theory’ of Alfred Wegner—about 300 million years ago, all the present-day continents of the world were united as an aggregated supercontinent called ‘Pangaea’, during the Carboniferous period.
• Later on, it began to break apart and the pieces drifted in two directions, e.g., (1) equatorward movement and (2) Westward movement. Actually, the continental crust (Sial) was floating over the oceanic crust (Sima). But this theory could not fully explain the causes of earthquakes or the formation of most of the continents, oceans, mountains and volcanism etc.
• In the 1960s, an elegant and exciting theory emerged that provided an elegant unifying explanation for all geological processes past and present. This theory is called ‘Plate Tectonics’ and it is a great scientific achievement of the decade of 1960s.

“WBBSE Class 8 Geography Chapter 2 notes, Unstable Earth”

Definition of the plates and Plate-tectonics: The rigid lithospheric slabs or rigid and solid crustal layers are called ‘Plates’. The whole mechanism of the evolution, nature and motion of Plates and resultant reactions is called ‘Plate Tectonics’, in other words, the whole process of plate motions is referred to as ‘Plate Tectonics’.

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It may be mentioned that the term ‘Plate’ was first used by Canadian geophysicist J. T. Wilson in 1965. Makenzie and Parker discussed in detail the mechanism of plate motion in 1967. W. J. Morgan and Le Pichon elaborated on the various aspects of Plate Tectonics in 1968. Now Continental Drift and displacement are considered a reality on the basis of Plate Tectonics.

The theory of Plate Tectonics comprises only four basic concepts:

1. The outer portion of the earth—its crust and uppermost segment of the mantle (i.e., lithosphere) is composed of large rigid units called Plates.
2. The plates move in response to the flow of the heat-softened ‘asthenosphere’ beneath them.
3. Most of the World’s large-scale geological activity, such as volcanic eruptions, and earthquakes, occurs at near plate boundaries.
4. The interiors of plates are relatively quiet geologically, with far fewer and milder earthquakes than occur at plate boundaries and little volcanic activity.

There are six large (major) and twenty small (minor) plates. The six major plates are the

1. Eurasian plate,
2. Indo-Australian plate,
3. American plate,
4. Pacific plate,
5. African Plate and
6. Antarctic plate.

Movements of the Plate and Geological History: The earth’s plates move relative to each other in several ways, and plate boundaries are categorized according to which type of movement they demonstrate. Here instead of a whole continent portion of the ocean is also attached to the plate. Here the North American continent plate moves westward away from Europe along with the western half of the Atlantic ocean.

“Class 8 WBBSE Geography Chapter 2 notes, Unstable Earth study material”

There are three major types of boundaries:

1. Divergent or constructive plate boundary, where plates move apart,
2. Convergent or destructive plate boundary, where p|ates move together, and
3. Neutral or transform plate boundary, where plates move past one another in opposite directions.
4. Divergent or constructive plate boundary: When two plates diverge or follow different directions, the narrow space between the two is called a ‘rift’. The magma then fills this space. The such a plate boundary is called ‘divergent’ or ‘constructive plate boundary’.
5. Throughout the period of divergence, ocean basins continue to expand as molten rock erupts, creating new oceanic lithosphere that builds up to form the mid-ocean ridge. The process of plate growth at the mid-ocean ridge is known as ‘sea-floor spreading’. Japan and its adjacent islands along the western coast of the Pacific Ocean have been formed in this way.
6. Convergent or destructive plate boundary: When two plates converge or move towards the same point, they may either collide against each other or push the third plate with their combined force. The boundary of such plates is also called a ‘convergent or destructive ‘ plate boundary. The Himalayas were formed in this way from the sediments of the Tethys sea between the European and Indian plates.
7. Neutral or Transform plate boundary: Where two plates slide past or grind past one another along transform faults and thus crust is neither created nor destroyed, this is known as ‘Neutral or transform plate boundary’.Such is the case with San Francisco and Los Angeles, which are located within the San Andreas transform zone between the North American and Pacific plates.

“WBBSE Class 8 Geography Chapter 2, Unstable Earth study guide”

Chapter 2 Unstable Earth Earth Volcanism

 

Volcanism: The process responsible for the upward movements of molten rock or magma through the Earth’s crust is called ‘volcanism’.

Volcano: The word ‘Volcano’ is derived from the greek term ‘Vulcan’ meaning the god of the underground.

A volcano is a vent or opening in the Earth’s crust through which magma and other materials erupt from the interior of the earth. Volcanoes usually consist of a conical hill or mountain formed from molten rock or lava, ashes and rock fragments ejected through the volcanic vent.

Parts of a Volcano:

1. Vent—The vent is the hole through which the volcanic materials come out.
2. Volcanic Pipe—Volcanic pipe is the narrow opening which connects the vent with the interior.
3. Crater—Crater is the funnel-shaped hollow at the core of the volcano.

Different types of volcanic eruptions: When solid, liquid and gaseous materials are thrown out of the interior of the earth, it is known as a ‘volcanic eruption’. There are two main modes of eruption-

• Central Eruption and
• Fissure Eruption:

1. Central Eruption: When lava erupts through a vent, violent explosion takes place. It results in the formation of the volcanic cone; such as Vesuvius and Fujiyama. A crater is formed at the summit. Most of the volcanoes are of cone and crater type. A chain of such volcanoes forms a volcanic mountain range.
2. Fissure Eruption: When there is a quiet upwelling of lava through fissures over a large area, it is known as a ‘fissure eruption’. It gives rise to extensive lava plains or plateaus. The Decan Trap of Peninsular India is an example of this type. It covers an area of 5 lahks sq. km with a thickness of lava sheets exceeding 1000 metres. Fissure eruption has taken place in Ireland and Iceland also.

Classifications of Volcanoes: Based on the frequency and nature of eruptions volcanoes are classified into three major types. These are as follows :

• Active volcanoes: The volcanoes that erupt frequently or are always emitting lava are called ‘active volcanoes’. Mouna Loa in Hawaiian islands is the largest active volcano of the world, other important active volcanoes are the ‘Vesuvius’ of Italy, ‘The Stromboli’ of Lipari island, ‘Etna’ of Sicily, ‘Erebus’ of Antarctica and ‘Barren’ island of India.

Active Volcanoes are of two types: (1) Incessant and (2) Intermittent volcanoes.

1. The volcano that erupts incessantly is known as an ‘incessant volcano’, e.g. Mt. Erebus of Antarctica,
2. The volcano that emits with intervals, is known as an ‘intermittent volcano’, e.g. Vesuvius of Italy.

2. Dormant Volcanoes: Dormant volcanoes are also called sleeping volcanoes’. These volcanoes have been active in the past and have stopped ejecting lave now, but can erupt again in any time, e.g. Mt Fujiyama of Japan.

“WBBSE Class 8 Unstable Earth notes, Geography Chapter 2”

3. Extinct Volcanoes: The volcanoes which have never erupted in human history are’ called ‘extinct’ or ‘dead volcanoes’, e.g. Mt. Kilimanjaro in Africa, Mt. Popa in Myanmar, Mt. Cotopaxi in Ecuador.

‘Aa’: A type of dense, viscous volcanic lava with a rough blocky structure is known as ‘Aa’, in the Hawaiian language.

‘Pa hoe hoe’: A type of highly fluid lava that spread out in sheets over vast areas from the volcanoes of the Hawaiian island is called ‘Pa hoe hoe’ in the Hawaiian language. The upper surface of this type of lava cools very quickly and looks like a twisted rope.

The constructive Effects of volcanoes:

1. volcanic eruptions increase the fertility of the soil.
2. The water of hot springs, Geysers is considered very useful for people.
3. The volcanoes result in the formation of precious stones, minerals, such as diamonds are due to volcanic eruptions.
4. The volcanoes provide us with crater lakes and depressions caused by the volcanoes.

Disadvantages of volcanoes:

• Volcanoes are highly destructive.
• They cause much loss of life and property.
• Many towns are buried under Lava.
• Crops are destroyed in large areas.
• Eruptions in the sea kill millions of fish.
• In the 1883 Krakatoa eruption 36000 persons were killed due to high tidal waves.
• Volcanic ash pollutes the atmosphere.
• Many poisonous gases kill animals in some areas.

Earthquake: Earthquakes are sudden, rapid and detectable vibrations, tremors or shaking caused in the earth’s crust by tectonic movements or volcanic eruptions.

 

Chapter 2 Unstable Earth: Causes Of Earthquakes

 

Major causes of Earthquakes: Earthquakes occur frequently in unstable portions (subduction zones) of the earth’s crust. The two major endogenetic causes of earthquakes are volcanic eruptions and tectonic forces.

Minor causes of earth tremors include landslides or avalanches. Artificial or man—induced earthquakes or anthropogenic earthquakes are caused by human activities. So, there are two types of earthquakes, i.e. Natural earthquakes, and Artificial (anthropogenic) earthquakes.

Natural causes of Earthquakes:

1. The tectonic earthquakes are caused due to:

1. The dislocation of rock blocks during faulting activity,
2. Drifting of the continents and plates of the earth,
3. Mountain building movements (orogenic process) etc.

2. Volcanic earthquakes are caused due to:

1. Volcanic eruptions or explosions of the volcanoes and
2. Movements of molten rock (magma/lava) below, or within the crust.

3. Isostatic earthquakes are caused due to imbalance in the geological processes generally, the earthquakes of active zones of mountain building are included in this category.

4. Plutonic earthquakes occur at greater depths when heat is radiated from the earth’s interior the earth’s crust may contract giving rise to earthquakes.

5. Heavy rainfall in mountain regions often causes landslides that may cause earthquakes.
6. Avalanches in high mountain regions may also cause earthquakes.

“Class 8 WBBSE Geography Chapter 2, Unstable Earth easy explanation”

Artificial or Anthropogenic (Man-induced) Earthquakes: Besides the natural causes of earthquakes, human activity also causes artificial earthquakes. These anthropogenic earthquakes are caused by the pumping of water and mineral oil reserves from underground aquifers and oil reserves respectively, deep underground mining, blasting of rocks by dynamites for constructional purposes (e.g. for the construction of roads, dams, reservoirs etc.), nuclear explosion, storage of huge volume of water in big reservoirs (Koyna earthquake in Maharashtra, India of 1967 due to Koyna reservoir) etc.

Focus or Centre of the Earthquake: The place of origin of an earthquake inside the earth is called the ‘centre’ or ‘focus of the earthquake’. Observations have shown that most of the centre or focus of the earthquakes lie within 16 kilometres from the surface of the earth.

It may be at a depth from 50 to 100 km and only a single earthquake occurs at still greater depths. The shock waves travel in all directions from the focus.

1. Epicentre: The point on the earth’s surface just vertically above the centre or focus of the earthquake which experiences the greatest intensity is called ‘Epicentre’. Being nearest, the intensity of vibration is maximum at the epicentre.

So, an earthquake is the strongest and most destructive near the epicentre. Also, it is worth remembering that the effects of an earthquake are felt on a much wider area if its focus lies deep below the earth’s surface.

Speed of the earthquake waves: On the earth’s surface the speed of earthquake waves varies between 5 to 8 km per second, with the speed increasing inside the earth’s crust.

“WBBSE Class 8 Geography Chapter 2 notes, Unstable Earth PDF”

Seismic waves and their types: A shock wave generated by an earthquake is called a seismic wave’. Seismic waves are of three basic types: P-wave, S-wave and L-wave. The study of the waves is also important for understanding how earthquakes cause destruction to things in their path.

1. Primary wave or Push waves (P-wave): This is the fastest seismic wave (6 to 8 km/ Sec.) and reaches the earth’s surface before point of happening or focus by the displacement of surrounding particles. They are transmitted through solids, liquids and gases.
2. Secondary waves or Shake waves (S-wave): They travel through solids only under the crust. It reaches the earth’s surface immediately after the Primary (P) wave (3-5 km/Sec) The speed of secondary (S) waves is about 3/5 as fast as primary waves.
3. Surface waves/Long Waves(L- waves): They travel on earth’s surface. L (surface)-waves travel at around 3 km/sec. The waves cause vibrations inside the earth. These waves spread out from the epicentre of the earthquake. These waves are responsible for most of the damage caused by earthquakes.

“WBBSE Class 8 Geography Chapter 2, Unstable Earth important questions”

Measurement of Earthquakes: Earthquakes are studied by a special subject known as ‘seismology’ or the science of earthquakes (from the greek word ‘seismic’ meaning earthquakes). That is why the instrument recording the shock waves is called the ‘Seismograph’.

This instrument helps in determining the source of the earthquake, the movements of the earthquake, waves etc. The function of a seismograph is to measure the intensity of the earthquake shocks. It can record and calculate the distance of vibrations thousands of kilometres away including the focus and the epicentre.

 

Seismogram: During an earthquake, the oscillation of the marker of a seismograph marks the paper to create a graph is called a ‘seismogram’.

Richter Scale: The intensity or severity of an earthquake is measured with reference to a scale called the ‘Richter Scale’. Prof.Charles F. Richter of California University created this scale, in 1935, which is named after him. This scale is placed on the seismograph.

It is a logarithmic scale and uses a system of rating. This scale ranges from 0 to 9, but in practice, there is no upper limit. Every increase or one number of magnitude means the motion is 10 times greater. Earthquakes of 7 and above intensity of the Richter scale are highly destructive.

Modified Mercalli Scale: The effect of an earthquake at a given spot is measured using an intensity scale—the Modified Mercalli Scale. The intensity varies with distance from the epicentre. It uses subjective analysis like the type of rock, earth, dwelling units etc. The scale has 12 divisions or degrees ranging from low to high intensity.

“Class 8 Geography Unstable Earth notes, WBBSE syllabus”

Earthquake Prone Regions of the World: Earthquakes are more common along fault lines running through the weakness zones of the earth. Earthquakes can also take place where there is a Hot Spot on a plate.

Convergent, divergent and transform (neutral) plate margins have earthquakes occurring along them. But earthquakes are frequent along the convergent plate margins because there is more intensity. Earthquakes occur in almost every part of the world, but they are frequent in the following well-defined belts.

1. The Circum-Pacific Belt: About 68% of all earthquakes are observed in the vast region of the Pacific Ocean as ‘the Pacific Ring of Fire’ or ‘Fiery Ring of the Pacific’ or ‘Fiery Girdle of the Pacific’. It is closely linked with the region of crustal dislocations and volcanic phenomena. Chile, California, Alaska, Japan, Phillippines, New Zealand and the Mid-ocean areas have many minors and major earthquakes in this belt.
2. The Mid-World Mountain Belt: About ZlS^qarthquakes of the world originate in this belt. It extends along the fold mountains of Europe and Asia. It runs through the Alps, the Caucasus and the Himalayas. This belt has folded mountains, large depressions and active volcanoes.
3. Other Areas: The remaining 11% of earthquakes of the world originate in other areas such as the Mid-Atlantic, Rift valley of East Africa, Central Siberia, Red Sea and the Dead Sea zone.

Earthquake-prone Regions of India: Our country India is an earthquake-prone land. About .two-third of this country is prone to earthquakes. On the basis of vulnerability to earthquakes, India can be divided into five seismic zones.

The earthquakes in India are at present mainly confined to the Himalayan region and its foothills. They are also felt in the Ganges-Brahmaputra Valley.

“WBBSE Class 8 Chapter 2 Geography, Unstable Earth solutions”

But the earthquakes in the Koyna Dam region in 1968 and Latur in 1993 in the Deccan Tableland (Plateau) came as surprise because it was considered a earthquake-free region.

Scientists believe that while in the former case reservoir caused cracks in the rocks, in the latter case the movement of the Indian Plate might have been the cause.

 

Effects of Earthquakes: The change brought by earthquakes on the surface of the earth:

1. The earthquakes sometimes cause landslides and give to rise to the formation of block mountains and rift valleys.
2. The earthquake block the flow of rivers and causes lake formation.
3. The earthquakes sometimes changed the courses of rivers due to landslides causing severe floods.
4. Depression-causing lakes are formed.
5. Many springs and waterfalls are formed.
6. They can cause vertical and lateral displacement of parts of the crust and raise or lowering of parts of the sea floor.

Destructive Effects:

1. There is loss of life and property due to violent earthquakes.
2. Fractures and cracks are formed, and railway lines are twisted.
3. The earthquake causes tsunamis or tidal waves which destroy houses, buildings and also the life of man and animals.
4. Dislocate electric wire and cause a fire.
5. The earthquakes cause landslides and disturb the isostatic equilibrium.
6. Many towns are destroyed. The communication system is disturbed due to the destruction of roads, bridges etc.

Constructive Effects: Earthquakes have some advantages also—

1. Sometimes earthquakes cause the emergence of the coast and bring fertile shores out of the water to give a chance to develop crop production.
2. The rift valleys are converted into lakes which become a source of water.
3. Sometimes earthquakes cause the formation of hot springs which are very useful to people.
4. Many minerals, gems and precious stones come out of the interior of the earth.
5. Bays are formed along the coast to provide new harbours.
6. Earthquakes provide knowledge about the interior of the earth.
7. Sometimes the earthquake waves help in the formation of fold mountains which are very good from a climatic point of view.
8. The earthquakes sometimes cause submergence in coastal lands and result in the formation of inlets, bays, and gulfs which make the site favourable for the development of fishing and shipping etc.

Tsunami: Tsunami is a Japanese word, that means waves of harbour’ (Tsu = harbour, nami – Wave) or, it also means ferocious oceanic quake’ (Tsu = ferocious, ‘na’ = oceanic; mi = quake). It is known as destructive sea waves.

“WBBSE Geography Class 8 Unstable Earth, Chapter 2 key concepts”

When a severe earthquake takes place below the ocean bed, its tremors give rise to huge wall-like sea waves rushing to the coastal areas. These sea waves are often as high as 27 metres, and as long as 160 kilometres travelling at a jet speed of 800 km/hour. Quite common along the coast of Japan and certain regions of the Pacific Ocean, Tsunamis can be more destructive.

About 3 lakh lives were lost and enormous damage was caused over eleven countries in Southeast Asia, including India, by a tsunami resulting from an earthquake of 8-9 magnitude under the Indian Ocean on 26th December 2004.

Prevention of Earthquake: Forecast and Essential Planning—Man is unable to prevent earthquakes, all he can do is to take steps for safety. Though earthquakes can not be predicted, but some preventive measures and planning can save many lives.

Sometimes our own observations, like sudden changes in atmospheric conditions and abnormal behaviour of animals, can help us to forecast the arrival of an earthquake. The suitable earthquake-proof building structures need to be encouraged. Disaster management infrastructures are also needed.

“WBBSE Class 8 Geography Chapter 2, Unstable Earth summary”

Disaster Management:

1. Identifying the risk factors in a building.
2. Planning to fight hazards.
3. To keep essential materials to the case of an emergency handy.
4. To repair the weak and dilapidated parts of a house.
5. To take shelter under stout furniture during an earthquake.
6. Appraising the injuries and damages when the tremors stop.
7. Disaster management and executing the pre-planned steps.

What to do when an earthquake occurs:

1. Come out of the house or school building quickly and stay in the open field.
2. Quickly go under a table.
3. Close the door and windows and stay indoors.
4. Pack essentials before leaving the house.
5. Disconnect electricity.

WBBSE Notes For 8 Class Middle School Geography