PHYSIOGRAPHIC DIVISION OF INDIA
India has a variety of physical features ranging from small islands to one of the highest peaks of the world. Physiographically, India can be divided into three major physiographic units-the mountain, the peninsular plateaus, and the plains. To these may be added the fourth, namely, the coasts and islands.
MOUNTAINS The Peninsular Mountains The mountains of peninsular India can be classified as follows:
The Western Ghats (The Sahyadri) About 1,600 km long and with an average elevation of 1,000-1,300 m, they run along the west coast from the south of the Tapti river valley to Kanyakumari. The Deccan Trap constitutes the northern portion of the Ghats. The southern part of the Ghats is composed of Archaean gneisses, schists and charnockites.
The Eastern Ghats These irregular hill ranges stretch from northern Orissa to the Nilgiris in Kerala and Tamil Nadu across coastal Andhra. They are mainly ranges of garnetiferous sillimanite gneisses or khondalite and charnockites. The highest peak is at 1,680 m in Vishakhapatnam district of Andhra Pradesh.
The meeting point of the Western and Eastern Ghats in the Nilgiri Hills has the highest point at Doda Betta peak.
The Vindhya Range Running from Sasaram (Bihar) in the east to Jobat (Gujarat) in the west, the Vindhya range separates northern India from the southern mainland. Mostly composed of sandstones and quartzites, it is lavaridden in the west.
The Satpura Ra,zge Covered with lava, the range extends from the Narmada valley in the north to the Tapti valley in the south. Its northern and southern borders are composed of sandstone, while the eastern section has Gondwana and Archaen gneisses. The average elevation is 1,030 m above sea level, with the highest point at Dhupgarh (1,350 m) near Pachmarhi (Madhya Pradesh).
The Aravallis M~de of the rocks of quartzites, gneisses and schists belonging to the Pre-Cambrian age, the Aravalli ranges constitute one of the most ancient fold mountain ranges of the world. Stretching 800 km from the north-east to south-west of India, they separate the semi-desert and fertile regions of Rajasthan. The Gurusikhar peak (1,722 m) of the Abu Hills is the highest point of the range.
Showing posts with label Continents. Show all posts
Showing posts with label Continents. Show all posts
Wednesday, October 28, 2009
Australia
Australia is the smallest continent. It is also the only country that is also a continent. It covers 7,682,300 sq km, or about 5 per cent of the earth's land area. Mainland Australia extends from 12°S to 38°S latitudes (12°S to 44"S if we include Tasmania) and 114° E to 154° E longitudes. Australia lies entirely in the Southern Hemisphere.
Australia can be divided into three major physical divisions-from west to east, the Western Plateau, the Central Lowlands, and the Eastern Highlands. The Western Plateau covers the western two-thirds of Australia. Most of the land is flat and covered with small shrubs, though at places isolated mountain ranges rise above the general level. A vast, dry, treeless plateau called the Nullarbor Plain extends along the southern edge of the Western Plateau.
The Central lowlands have the lowest elevations in Australia. Lake Eyre, the lowest point in Australia (16 metres ,below sea level), lies in the Central Lowlands. The Lowlands extend from the Gulf of Carpentaria in the north, across the continent to the southern shores. The region receives scanty rains, except in areas along the north and south coasts imd near the Eastern Highlands. The Eastern Highlands run almost parallel to the east coast of Australia, extending from Cape York Peninsula in the north to Tasmania in the south.
The region includes the highest elevations in Australia. Along the Pacific Coast lies a low plain bordered by sandy beaches and rocky cliffs. The Eastern Highlands are known as the Great Dividing Range because their slopes divide the flow of the rivers in the region. Those flowing down the eastern slopes drain into the ocean. Those rurming down the western slopes flow to the Central Lowlands. The Eastern Highlands are broad and low in the north and narrow and high in the south.
Australia's highest mountains rise in the Australian Alps in the extreme southern part of Eastern Highlands. Mount Kosciusky (2,228 m), in the Snowy Range of. the Alps, is the highest peak in Australia. The highlands drop steeply in the east towards the Pacific Ocean and more gently in the west towards the Central Lowlands. The Highlands are not a single range; they consist mainly of high plateaus that are broken in many places by gorges, hills, and low mountain ranges.
Most of the rivers of Australia go dry in some parts of the year and fill with water only during the rainy season. River Murray, originating from the Snowy Mountains in the Alps and flowing westward, is the continent's longest permanently flowing river. During the dry season in southern Australia, the Murray is fed by River Darling, Austalia's longest river. River Darling begins in the central part of the Eastern Highlands and flows southwestwards.
Deserts cover about a third of Australia. The four major deserts are the Simpson (western edge of the Central Lowlands), the Gibson, the Great Sandy and Great Victoria (central part of the Western Plateau) Off the north-east coast of Australia exists the Great Barrier Reef-the world's largest coral reef, extending more than 1900 km in length.
Australia lies south of the equator and so its seasons are opposite those in the Northern Hemisphere. Northern Australia lies in the tropics and so experiences warm season throughout the year. The wet season lasts from November through April and the dry season lasts from May through October. Southern Australia has four seasons-winter (June through August) is the coolest and wettest season and summer (December through February) is the hottest and driest season.
Australia can be divided into three major physical divisions-from west to east, the Western Plateau, the Central Lowlands, and the Eastern Highlands. The Western Plateau covers the western two-thirds of Australia. Most of the land is flat and covered with small shrubs, though at places isolated mountain ranges rise above the general level. A vast, dry, treeless plateau called the Nullarbor Plain extends along the southern edge of the Western Plateau.
The Central lowlands have the lowest elevations in Australia. Lake Eyre, the lowest point in Australia (16 metres ,below sea level), lies in the Central Lowlands. The Lowlands extend from the Gulf of Carpentaria in the north, across the continent to the southern shores. The region receives scanty rains, except in areas along the north and south coasts imd near the Eastern Highlands. The Eastern Highlands run almost parallel to the east coast of Australia, extending from Cape York Peninsula in the north to Tasmania in the south.
The region includes the highest elevations in Australia. Along the Pacific Coast lies a low plain bordered by sandy beaches and rocky cliffs. The Eastern Highlands are known as the Great Dividing Range because their slopes divide the flow of the rivers in the region. Those flowing down the eastern slopes drain into the ocean. Those rurming down the western slopes flow to the Central Lowlands. The Eastern Highlands are broad and low in the north and narrow and high in the south.
Australia's highest mountains rise in the Australian Alps in the extreme southern part of Eastern Highlands. Mount Kosciusky (2,228 m), in the Snowy Range of. the Alps, is the highest peak in Australia. The highlands drop steeply in the east towards the Pacific Ocean and more gently in the west towards the Central Lowlands. The Highlands are not a single range; they consist mainly of high plateaus that are broken in many places by gorges, hills, and low mountain ranges.
Most of the rivers of Australia go dry in some parts of the year and fill with water only during the rainy season. River Murray, originating from the Snowy Mountains in the Alps and flowing westward, is the continent's longest permanently flowing river. During the dry season in southern Australia, the Murray is fed by River Darling, Austalia's longest river. River Darling begins in the central part of the Eastern Highlands and flows southwestwards.
Deserts cover about a third of Australia. The four major deserts are the Simpson (western edge of the Central Lowlands), the Gibson, the Great Sandy and Great Victoria (central part of the Western Plateau) Off the north-east coast of Australia exists the Great Barrier Reef-the world's largest coral reef, extending more than 1900 km in length.
Australia lies south of the equator and so its seasons are opposite those in the Northern Hemisphere. Northern Australia lies in the tropics and so experiences warm season throughout the year. The wet season lasts from November through April and the dry season lasts from May through October. Southern Australia has four seasons-winter (June through August) is the coolest and wettest season and summer (December through February) is the hottest and driest season.
Europe
Europe ranks sixth in terms of area of continents. It covers 10,521,100 sq km or about one-fifteenth of the world's land area. It extends between 25° Wand 65° E longitudes and 35° Nand 73° N latitudes-from the Arctic Ocean in the north to the Mediterranean Sea, the Black Sea and the Caucasus Mountains in the south, and from the Atlantic Ocean in the west to the western part of Russia in the east. Europe is a westward extension from northwestern Asia. Asia and Europe are not separated completely, and the two regions are sometimes regarded as one continent-Eurasia. However, because of its certain distinctive characteristics, Europe is considered to be a continent by itself.
Europe is divided into four major physical divisionsthe Northwest Mountains, the North European Plains, the Central Uplands and the Alpine System. The Northwest Mountains extend from Finland through Sweden, Norway and the British Isles to Iceland, and include some of the oldest rock formations on earth. The mountains have worn down over the years and the average elevation is not very high. The area is rich in metallic minerals such as iron and copper.
The North European Plains extend from the Urals in the east to the Atlantic coast in the west. The region also includes part of south-eastern England. The plains are broadest in the eastern part and narrow down towards the west. To the north of the North European Plains lie the Northwest Mountains, the White Sea and the Baltic Sea, and to the south lie the Central Uplands. The plains comprise flat and rolling land and some hills. They constitute some of the world's most fertile farmlands. In some places beneath the plains lie deposits of high-grade fossil fuels such as coal, oil and natural gas.
The Central Uplands region is constituted of a variety of low mountains, hills and plateaus that run through the central part of Europe. The uplands include the Meseta in Spain and Portugal, the Massif Central and Juna mountains in France, the Black Forest in Germany and .several low ranges in the Czech and Slovak republics. Most of the land is rocky and has poor soil for farming, but some river valleys in the region are suitable to agriculture. Parts of the region are rich in mineral deposits.
The Alpine Mountain System comprises chains of high mountains stretching from the Atlantic Ocean in the west to the Caspian Sea in the east. Important mountain ranges include the Alps (covering part of south-eastern France and northern Italy, most of Switzerland, and parts of southern Germany, Austria and northern Yugoslavia), the Apennines (covering much of Italy), the Alpines (including the Dinaric Alps of Yugoslavia and Greece; the Balkans of Bulgaria; and the Carpathians; and the Caucasus).
The highest mountain peak of Europe is Mount Elbrus (5,633 m) in the Caucasus.
Europe has an irregular and a long coastline of about 60,957 km. Large portions of sea have penetrated deep into the land, with the result that most of Europe (except the heart of Russia) are within about 480 km of a seacoast. The land curves in and out in a series of large and small peninsulas-the Scandinavian peninsula (Norway and Sweden), Jutland (Denmark), the Iberian peninsula (Portugal and Spain), the Apennine peninsula (Italy) and the Balkan peninsula (Albania, Bulgaria, Greece, and parts of Turkey and Yugoslavia).
Thousands of islands lie off the coast of Europe. The largest and most important of these is Great Britain, one of the British Isles.
The Volga is Europe's longest river, flowing 3,531 km through Russia to the Caspian Sea. River Rhine flows through the Alps through western Germany and the Netherlands to the North Sea. The Danube, Europe's second longest river, flows from southern Germany through Austria, Czechoslavakia, Hungary, Yugoslavia, Bulgaria and Romania to the Black Sea.
The salt water Caspian Sea, which lies partly in Europe and partly in Asia, is also the world's largest lake. Its northern shore, lying 28 metres below sea level, is Europe's lowest point. Europe's largest freshwater lake is the Ladoga in Russia. Finland has about 60,000 lakes-the country is known as the 'land of thousand lakes'.
Most of Europe experiences mild weather. Northern Europe has longer, colder winters and shorter cooler summers than southern Europe. Eastern Europe experiences longer and colder winters and shorter and hotter summers than western Europe.
Europe is divided into four major physical divisionsthe Northwest Mountains, the North European Plains, the Central Uplands and the Alpine System. The Northwest Mountains extend from Finland through Sweden, Norway and the British Isles to Iceland, and include some of the oldest rock formations on earth. The mountains have worn down over the years and the average elevation is not very high. The area is rich in metallic minerals such as iron and copper.
The North European Plains extend from the Urals in the east to the Atlantic coast in the west. The region also includes part of south-eastern England. The plains are broadest in the eastern part and narrow down towards the west. To the north of the North European Plains lie the Northwest Mountains, the White Sea and the Baltic Sea, and to the south lie the Central Uplands. The plains comprise flat and rolling land and some hills. They constitute some of the world's most fertile farmlands. In some places beneath the plains lie deposits of high-grade fossil fuels such as coal, oil and natural gas.
The Central Uplands region is constituted of a variety of low mountains, hills and plateaus that run through the central part of Europe. The uplands include the Meseta in Spain and Portugal, the Massif Central and Juna mountains in France, the Black Forest in Germany and .several low ranges in the Czech and Slovak republics. Most of the land is rocky and has poor soil for farming, but some river valleys in the region are suitable to agriculture. Parts of the region are rich in mineral deposits.
The Alpine Mountain System comprises chains of high mountains stretching from the Atlantic Ocean in the west to the Caspian Sea in the east. Important mountain ranges include the Alps (covering part of south-eastern France and northern Italy, most of Switzerland, and parts of southern Germany, Austria and northern Yugoslavia), the Apennines (covering much of Italy), the Alpines (including the Dinaric Alps of Yugoslavia and Greece; the Balkans of Bulgaria; and the Carpathians; and the Caucasus).
The highest mountain peak of Europe is Mount Elbrus (5,633 m) in the Caucasus.
Europe has an irregular and a long coastline of about 60,957 km. Large portions of sea have penetrated deep into the land, with the result that most of Europe (except the heart of Russia) are within about 480 km of a seacoast. The land curves in and out in a series of large and small peninsulas-the Scandinavian peninsula (Norway and Sweden), Jutland (Denmark), the Iberian peninsula (Portugal and Spain), the Apennine peninsula (Italy) and the Balkan peninsula (Albania, Bulgaria, Greece, and parts of Turkey and Yugoslavia).
Thousands of islands lie off the coast of Europe. The largest and most important of these is Great Britain, one of the British Isles.
The Volga is Europe's longest river, flowing 3,531 km through Russia to the Caspian Sea. River Rhine flows through the Alps through western Germany and the Netherlands to the North Sea. The Danube, Europe's second longest river, flows from southern Germany through Austria, Czechoslavakia, Hungary, Yugoslavia, Bulgaria and Romania to the Black Sea.
The salt water Caspian Sea, which lies partly in Europe and partly in Asia, is also the world's largest lake. Its northern shore, lying 28 metres below sea level, is Europe's lowest point. Europe's largest freshwater lake is the Ladoga in Russia. Finland has about 60,000 lakes-the country is known as the 'land of thousand lakes'.
Most of Europe experiences mild weather. Northern Europe has longer, colder winters and shorter cooler summers than southern Europe. Eastern Europe experiences longer and colder winters and shorter and hotter summers than western Europe.
Antarctica
Antarctica, with an area of 14,000,000 sq km, surrounds and covers the South Pole. The continent is the coldest and iciest region on earth. The Antarctic icecap, which has been formed from layers of snow pressed together over millions of years, buries 98 per cent of the continent and forms the largest body of fresh water or ice in the world. The average thickness of ice on this continent is approximately two to five kilometres. Underneath the ice, Antarctica has mountains, lowlands and valleys.
The Transantarctic Mountains, made up of several ranges, cross the entire continent and divide it into two natural land regions-East Antarctica and West Antarctica. East Antarctica faces the Atlantic and Indian Oceans and covers more than half the continent. The region consists of rocks that are more than 570 million years old. The central part of East Antarctica is a plateau about 3000 metres above the sea level. The South Pole, the southern-most point on the earth, lies on this plateau. The south magnetic pole, the southern part indicated by compass needles, is also located in East Antarctica.
West Antarctica faces the Pacific Ocean. Much of the region lies below sea level and does not contain the old rock of East Antarctica. West Antarctica developed later as part of the Ring of Fire, a string of volcanoes encircling the Pacific Ocean. West Antarctica includes several mountain ranges and volcanoes. The Antarctic Peninsula is a mountainous strip of land pointing towards South America. The peninsula is said to be a continuation of the Andes mountain chain of South America. Near the peninsula are several islands; the South Shetland Islands include the Deception Island, an active volcano. Vinson Massif, the highest point in Antarctic (5,140 m), is part of the Ellsworth Mountains near the peninsula. Mount Erebus, Antarctica's most active volcano, lies on the Ross Island.
The Ross Sea and the Weddell Sea are gulfs that cut into Antarctica from opposite ends of the Transantarctic Mountains. There are smaller bays indenting the coastline.
Temperatures in Antarctica rarely reach above O°c. At the South Pole, temperatures as low as -95°C have been recorded during winters. The Antarctic winter lasts from May until August. Summer lasts from December until February. Extremely cold dry conditions exist on the inland plateau. The plateau has one of the driest climates on earth; it receives no rain and little new snow each year. Relatively mild and moist conditions mark the coastal regions.
The Transantarctic Mountains, made up of several ranges, cross the entire continent and divide it into two natural land regions-East Antarctica and West Antarctica. East Antarctica faces the Atlantic and Indian Oceans and covers more than half the continent. The region consists of rocks that are more than 570 million years old. The central part of East Antarctica is a plateau about 3000 metres above the sea level. The South Pole, the southern-most point on the earth, lies on this plateau. The south magnetic pole, the southern part indicated by compass needles, is also located in East Antarctica.
West Antarctica faces the Pacific Ocean. Much of the region lies below sea level and does not contain the old rock of East Antarctica. West Antarctica developed later as part of the Ring of Fire, a string of volcanoes encircling the Pacific Ocean. West Antarctica includes several mountain ranges and volcanoes. The Antarctic Peninsula is a mountainous strip of land pointing towards South America. The peninsula is said to be a continuation of the Andes mountain chain of South America. Near the peninsula are several islands; the South Shetland Islands include the Deception Island, an active volcano. Vinson Massif, the highest point in Antarctic (5,140 m), is part of the Ellsworth Mountains near the peninsula. Mount Erebus, Antarctica's most active volcano, lies on the Ross Island.
The Ross Sea and the Weddell Sea are gulfs that cut into Antarctica from opposite ends of the Transantarctic Mountains. There are smaller bays indenting the coastline.
Temperatures in Antarctica rarely reach above O°c. At the South Pole, temperatures as low as -95°C have been recorded during winters. The Antarctic winter lasts from May until August. Summer lasts from December until February. Extremely cold dry conditions exist on the inland plateau. The plateau has one of the driest climates on earth; it receives no rain and little new snow each year. Relatively mild and moist conditions mark the coastal regions.
South America
South America is the fourth largest continent in terms of area. It covers 17,806,000 sq km or about 12 per cent of the world's land area. It extends from 12° N to 55° S latitudes and 34° W to 81° W longitudes. It is almost completely surrounded by water-the Caribbean Sea on the north, the Atlantic Ocean on the northeast and east, the Pacific Ocean on the west and the Drake Passage on the south. The continent is connected to Central America by a narrow strip of land-the Isthmus of Panama.
The major physical divisions of South America are 'the Western Coastal Strip, the Western Mountains, the Central Plains and the Eastern Highlands. The Western Costal Strip is a narrow. strip of lowland along the Pacific Coast in the western part of South America. The Western Mountains, called the Andes Mountains, stretch for about 7200 kilometres from Venezuela in the north to Tierra del Fuego in the south. The Andes, which are young fold mountains, are the second highest mountain systems in the world, next only to the Himalayas. Mt Aconcagua (6,959 m) in Argentina is the tallest mountain in the entire western hemisphere. The Andes are also the world's longest mountain ranges above sea level. (The longest range is the Mid-Atlantic Ridge which rises from the bottom of the Atlantic Ocean.) Between the ranges of the Andes are some high plateaus. Lake Titicac~, one of the largest lakes of South America, is located in the Bolivian Plateau. The Andes also have several volcanic peaks, some active, others dormant or extinct. Cotopaxi in Ecuador is the highest active volcano in the world.
The Central Plains, covering about three-fifths of South America, lie between the Andes and the Eastern highlands. They are made up of the Llamos, rolling grasslands in the Orinico river basin of Colombia and Venezuela; the Selva, tropical rain forest of the Amazon river basin in Bolivia, Brazil and Peru; the Gran Chaco, hardwood serial forest in north-central Argentina, western Paraguay and southern Bolivia; the Pampas, vast grasslands in Argentina.
The Eastern Highlands consist of the Guyana Highlands and the Brazilian Highlands separated by the Amazon basin. Mountains of the Eastern Highlands are lower and older than the Andes.
The Amazon, the Rio de Ie Plata, the Magdalena-Cauca the Orinoco and the Sao Francisco are the major rive systems of South America. The Amazon is the world' second longest river, but has the largest drainage basin Lake Maracaibo in Venezuela is the continent's largest lake The Angel Falls in South-eastern Venezuela is the highes water fall in the world.
There is a broad zone of desert running southward: from coastal Eucador along the coasts of Peru and Chill and through southern Argentina.
South America has a long coastline-32,000 km. Then are several major island groups- Tierra del Fuego grouF (the largest); the Juan Fernandez Islands; the Falklanc Islands; and the Galapagos Islands.
The continent experiences a variety of climates-from dry desert conditions of northern Chile to the heavy raim along the south-western coast.
The major physical divisions of South America are 'the Western Coastal Strip, the Western Mountains, the Central Plains and the Eastern Highlands. The Western Costal Strip is a narrow. strip of lowland along the Pacific Coast in the western part of South America. The Western Mountains, called the Andes Mountains, stretch for about 7200 kilometres from Venezuela in the north to Tierra del Fuego in the south. The Andes, which are young fold mountains, are the second highest mountain systems in the world, next only to the Himalayas. Mt Aconcagua (6,959 m) in Argentina is the tallest mountain in the entire western hemisphere. The Andes are also the world's longest mountain ranges above sea level. (The longest range is the Mid-Atlantic Ridge which rises from the bottom of the Atlantic Ocean.) Between the ranges of the Andes are some high plateaus. Lake Titicac~, one of the largest lakes of South America, is located in the Bolivian Plateau. The Andes also have several volcanic peaks, some active, others dormant or extinct. Cotopaxi in Ecuador is the highest active volcano in the world.
The Central Plains, covering about three-fifths of South America, lie between the Andes and the Eastern highlands. They are made up of the Llamos, rolling grasslands in the Orinico river basin of Colombia and Venezuela; the Selva, tropical rain forest of the Amazon river basin in Bolivia, Brazil and Peru; the Gran Chaco, hardwood serial forest in north-central Argentina, western Paraguay and southern Bolivia; the Pampas, vast grasslands in Argentina.
The Eastern Highlands consist of the Guyana Highlands and the Brazilian Highlands separated by the Amazon basin. Mountains of the Eastern Highlands are lower and older than the Andes.
The Amazon, the Rio de Ie Plata, the Magdalena-Cauca the Orinoco and the Sao Francisco are the major rive systems of South America. The Amazon is the world' second longest river, but has the largest drainage basin Lake Maracaibo in Venezuela is the continent's largest lake The Angel Falls in South-eastern Venezuela is the highes water fall in the world.
There is a broad zone of desert running southward: from coastal Eucador along the coasts of Peru and Chill and through southern Argentina.
South America has a long coastline-32,000 km. Then are several major island groups- Tierra del Fuego grouF (the largest); the Juan Fernandez Islands; the Falklanc Islands; and the Galapagos Islands.
The continent experiences a variety of climates-from dry desert conditions of northern Chile to the heavy raim along the south-western coast.
North America
North America is the third largest continent, extending from the Arctic Ocean in the north to South America in the south. It covers about 24,249,000 sq km or about a'sixth 6f the world's land area, and extends between (approximately) 84° N to 7° N latitudes and 180° W to 20° W longitudes.
The continent has four major physical divisions-the Canadian Shield, the Appalachian Mountains or Eastern Highlands, the Central Plains, and the Western Cordilleras. The Canadian Shield, a huge area of ancient rocks, covers most of Canada.
It is a reservoir of valuable mineral resources like gold, silver, nickel, iron, copper, platinum, radium, cobalt and uranium. A large part of the shield is made up of swamps and a number of lakes such as the Great Bear, Winnipeg and the Great Lakes (Lakes Superior, Michigan, Huron, Erie and Ontario). The famous Niagara Falls is located between Lake Erie and Lake Ontario.
The Appalachian Mountains, located in the north-east, are constituted of low rounded mountains, plateaus and valleys. A number of minerals are found here.
The Central Plains cover central Canada, mid-western United States and the coastal plains in Texas. The mid and southern parts are a vast low and flat river basin of the Missouri-Mississippi.
The Western Cordilleras are a mountainous region along the north to south of the western part of the continent. There are several parallel ranges. The Rocky mountains are North America's largest mountain range. The Alaska Range, the Coastal Range, the Sierra Nevada, the Cascade Range, etc., are the other ranges. Mt McKinley (6,194 m) in the Alaska Range is North America's highest mountain. Fertile valleys between the mountain ranges are major agricultural centres. The ranges also enclose intermontane plateaus-the Great Basin is the largest in termontane plateau ot the continent. Most of the rivers of North America rise in the Western Cordilleras. There are many acttve volcanoes in the Western Cordilleras, especially in Alaska and Mexico.
The Mississippi-Missouri-Ohio is the continent's longest river system. The Grand Canyon of River Colorado is the largest of its kind in the world. Lake Superior is the largest freshwater lake in the world. Great Salt Lake in Utah is even saltier than the ocean. Most North American deserts lie in the southwestern United States and northern Mexico.
North America's coastline-about 300,000 km-is longer than that of any other continent. A number of countries lie off the coasts of the continent-Greenland (part of the North American continent, but governed as a province of Denmark), Newfoundland, Vancouver, the Aleutian Islands, and the West Indies.
North America experiences the most varied range of climate-from extremely dry cold of the Arctic type to the hot tropic.
The continent has four major physical divisions-the Canadian Shield, the Appalachian Mountains or Eastern Highlands, the Central Plains, and the Western Cordilleras. The Canadian Shield, a huge area of ancient rocks, covers most of Canada.
It is a reservoir of valuable mineral resources like gold, silver, nickel, iron, copper, platinum, radium, cobalt and uranium. A large part of the shield is made up of swamps and a number of lakes such as the Great Bear, Winnipeg and the Great Lakes (Lakes Superior, Michigan, Huron, Erie and Ontario). The famous Niagara Falls is located between Lake Erie and Lake Ontario.
The Appalachian Mountains, located in the north-east, are constituted of low rounded mountains, plateaus and valleys. A number of minerals are found here.
The Central Plains cover central Canada, mid-western United States and the coastal plains in Texas. The mid and southern parts are a vast low and flat river basin of the Missouri-Mississippi.
The Western Cordilleras are a mountainous region along the north to south of the western part of the continent. There are several parallel ranges. The Rocky mountains are North America's largest mountain range. The Alaska Range, the Coastal Range, the Sierra Nevada, the Cascade Range, etc., are the other ranges. Mt McKinley (6,194 m) in the Alaska Range is North America's highest mountain. Fertile valleys between the mountain ranges are major agricultural centres. The ranges also enclose intermontane plateaus-the Great Basin is the largest in termontane plateau ot the continent. Most of the rivers of North America rise in the Western Cordilleras. There are many acttve volcanoes in the Western Cordilleras, especially in Alaska and Mexico.
The Mississippi-Missouri-Ohio is the continent's longest river system. The Grand Canyon of River Colorado is the largest of its kind in the world. Lake Superior is the largest freshwater lake in the world. Great Salt Lake in Utah is even saltier than the ocean. Most North American deserts lie in the southwestern United States and northern Mexico.
North America's coastline-about 300,000 km-is longer than that of any other continent. A number of countries lie off the coasts of the continent-Greenland (part of the North American continent, but governed as a province of Denmark), Newfoundland, Vancouver, the Aleutian Islands, and the West Indies.
North America experiences the most varied range of climate-from extremely dry cold of the Arctic type to the hot tropic.
African Continent
Africa is the second largest continent in terms of size, covering about one-fifth of the land area of the earth. Spread over 30,330,000 sq km, Africa is located between 35° 5 and 37° N latitudes and 50° E and 17° W longitudes. The African continent is separated from Europe by the Mediterranean Sea and from Asia by the Red Sea. The Strait of Gibralter in the north-west, the Suez Canal in the northeast and the Strait of Bab-el Mandeb connect Africa to Eurasia.
Africa is an enormous plateau,. most of which is covered by deserts, forests and grasslands. The continent can be divided into two major land regions-Low Africa and High Africa. Low Africa, consisting of northern, western and central Africa, is further subdivided into the Coastal Lowlands, the Northern Highlands, the Saharan Plateau, the Western Plateau, the Nile Basin and the Congo (Zaire) Basin. High Africa covers eastern and southern Africa and may be further subdivided into the Rift System, the Eastern Highlands, the Southern Plateau, the Coastal Lowlands and Madagascar. The Rift System, a spetial physical feature of Africa, consists of the Great Rift Valley, which is a series of parallel cracks in the earth that form deep, steep-sided valleys. Many of these valleys house lakes. There are several large lakes in High Africa. Lake Victoria is the largest lake in Africa and is the source of River Nile, the longest river in the world. Other large rift lakes include the Tanganyika, Nyasa, Albert and Turkana. The Rift System extends from Ethiopia in the east to Mozambique in the south-east. It is rich in volcanic soil and has some of Africa's best farmlands.
Deserts cover about two-fifths of Africa. The Sahara, the world's largest desert, stretches across northern Africa from the Atlantic Sea to the Red Sea. Other deserts include the Namib desert and the Kalahari desert in southern Africa. Grasslands cover more than two-fifths of Africa. Forests cover less than a fifth of the continent.
Other major African rivers include the Congo (Zaire)which carries the greatest volume of water among all the rivers of Africa-and the Niger, which discharge into the Atlantic, and the Limpopo and the Zambezi which drain into the Indian Ocean. The Nile flows northward from eastcentral Africa to the Mediterranean Sea.
Most of Africa's highest mountains have been created by volcanic activity. Mt Kilimanjaro (5895 m) in Tanzania and Mt Kenye (5199) in Kenya are extinct volcanoes. The Atlas mountain range, extending from Morocco to Tunisia, forms Africa's longest mountain chain and is of nonvolcanic nature.
About 90 per cent of the African continent lies within the tropics-Africa has the largest tropical area in the world.
Africa is an enormous plateau,. most of which is covered by deserts, forests and grasslands. The continent can be divided into two major land regions-Low Africa and High Africa. Low Africa, consisting of northern, western and central Africa, is further subdivided into the Coastal Lowlands, the Northern Highlands, the Saharan Plateau, the Western Plateau, the Nile Basin and the Congo (Zaire) Basin. High Africa covers eastern and southern Africa and may be further subdivided into the Rift System, the Eastern Highlands, the Southern Plateau, the Coastal Lowlands and Madagascar. The Rift System, a spetial physical feature of Africa, consists of the Great Rift Valley, which is a series of parallel cracks in the earth that form deep, steep-sided valleys. Many of these valleys house lakes. There are several large lakes in High Africa. Lake Victoria is the largest lake in Africa and is the source of River Nile, the longest river in the world. Other large rift lakes include the Tanganyika, Nyasa, Albert and Turkana. The Rift System extends from Ethiopia in the east to Mozambique in the south-east. It is rich in volcanic soil and has some of Africa's best farmlands.
Deserts cover about two-fifths of Africa. The Sahara, the world's largest desert, stretches across northern Africa from the Atlantic Sea to the Red Sea. Other deserts include the Namib desert and the Kalahari desert in southern Africa. Grasslands cover more than two-fifths of Africa. Forests cover less than a fifth of the continent.
Other major African rivers include the Congo (Zaire)which carries the greatest volume of water among all the rivers of Africa-and the Niger, which discharge into the Atlantic, and the Limpopo and the Zambezi which drain into the Indian Ocean. The Nile flows northward from eastcentral Africa to the Mediterranean Sea.
Most of Africa's highest mountains have been created by volcanic activity. Mt Kilimanjaro (5895 m) in Tanzania and Mt Kenye (5199) in Kenya are extinct volcanoes. The Atlas mountain range, extending from Morocco to Tunisia, forms Africa's longest mountain chain and is of nonvolcanic nature.
About 90 per cent of the African continent lies within the tropics-Africa has the largest tropical area in the world.
Asian Continent
Asia is the largest contine] covering almost a third of the world's land area. Asia, wi an area of 43,947,000 square kilometres, extends betwel 80° Nand 10° S latitudes, and 25°E and 170° W longitudE The entire Asian mainland lies north of the equator, b the islands associated with Asia extend into the southel
hemisphere. Most of Asia lies in the eastern hemispher and only a part of it extends to the western hemispher Asia extends from the Arabian peninsula, Turkey and Ur mountains eastward to the Pacific Ocean. From the Aret Ocean, it reaches south to the Indian Ocean.
Asia is home to a variety of natural features, rangin from the hot deserts of the south-west, the cold deser1 in the interior and the frozen north; and from barre un9ultivable regions to the fertile river valleys, coast" pl,ins and delta regions. The highest and lowest places OJ thr earth are in Asia. Mount Everest, the highest, rises 8,84: metres above sea level along the Nepal-Tibet border. Th,
Dead Sea shore, the world's lowest land, lies about 39' metres below sea level on the border between Jordan and Israel.
The five major physical divisions of Asia are the Northern Lowlands, the Central Mountains, the Southerr Plateaus, the Great River Valleys and the Island Groups The Northern Lowlands comprise the Siberian plain whid extends between the Ural mountains in the west and River Lena in the east.
Lake Baikal in Siberia is the deepest lakE in the world. The interior heartland of Asia is surrounded by mountains and deserts. The Central Mountains, comprising fold mountains and plateaus, lie south of the Northern Lowlands. Asia has more mountains than any other continent. The major Asian mountain systems meet to form a large group of rugged peaks and deep valleys, called the Pamir Knot. Sometimes referred to as the 'roof of the world', the Pamir Knot lies where Afghanistan, China, Pakistan and the Central Asian republics meet. From the Pamir Knot, the Hindukush range extends to the west, the Tian Shan to the north-east, the Kunlun to the east and the Karakoram and the Himalayas to the south-east. The Karakoram and the Himalayan ranges contain some of the highest peaks of the world. Some of the largest glaciers of the world are also found in the Karakoram range. Between the Karakoram and the Himalayas in the south and the Kunlun in the north lies the Tibetan plateau. Between the Kunlun and the Tien Shan in the further north lies the Tarim basin. In between the Tien Shan in the west and the mountain chains of north-east Siberia lie the ancient fold mountain ranges-the Altai, the Yablonoi and the Stanovoi-which house the Tarim basin and the vast cold desert of Gobi.
The Southern Plateaus lie to the south of the Central Mountains. Formed of very old rocks, the Southern Plateaus (comprising the plateau of Arabia, the Deccan plateau and the plateau of Yunnan) constitute the major part of the peninsulas projecting southward from mainland Asia. The Great River Valleys lie in-between the mountains and plateaus. Some of these river systems-the Tigris-Euphrates, the Indus, the Ganga-Brahmaputra, the Ayeyarwaddy, the Mekong, the Sikiang, the Chang Jiang (Yangtze-Kiang) and the Huang He-are very old. The Yangtze is Asia's longest river.
Three major island groups are located to the southeast and east of Asia-Indonesia, the Philippines and Japan. Most of these islands have a mountainous core surrounded by narrow coastal plains. Some islands still have active volcanoes.
Asia's coastline measures about 129,077 km.
Because of its tremendous size and varied physical
features, Asia experiences a variety of climates-the bitter cold of the polar north; the hot, dry desert environment of the centre and the southwest; and the hot, humid conditions of the tropical south.
hemisphere. Most of Asia lies in the eastern hemispher and only a part of it extends to the western hemispher Asia extends from the Arabian peninsula, Turkey and Ur mountains eastward to the Pacific Ocean. From the Aret Ocean, it reaches south to the Indian Ocean.
Asia is home to a variety of natural features, rangin from the hot deserts of the south-west, the cold deser1 in the interior and the frozen north; and from barre un9ultivable regions to the fertile river valleys, coast" pl,ins and delta regions. The highest and lowest places OJ thr earth are in Asia. Mount Everest, the highest, rises 8,84: metres above sea level along the Nepal-Tibet border. Th,
Dead Sea shore, the world's lowest land, lies about 39' metres below sea level on the border between Jordan and Israel.
The five major physical divisions of Asia are the Northern Lowlands, the Central Mountains, the Southerr Plateaus, the Great River Valleys and the Island Groups The Northern Lowlands comprise the Siberian plain whid extends between the Ural mountains in the west and River Lena in the east.
Lake Baikal in Siberia is the deepest lakE in the world. The interior heartland of Asia is surrounded by mountains and deserts. The Central Mountains, comprising fold mountains and plateaus, lie south of the Northern Lowlands. Asia has more mountains than any other continent. The major Asian mountain systems meet to form a large group of rugged peaks and deep valleys, called the Pamir Knot. Sometimes referred to as the 'roof of the world', the Pamir Knot lies where Afghanistan, China, Pakistan and the Central Asian republics meet. From the Pamir Knot, the Hindukush range extends to the west, the Tian Shan to the north-east, the Kunlun to the east and the Karakoram and the Himalayas to the south-east. The Karakoram and the Himalayan ranges contain some of the highest peaks of the world. Some of the largest glaciers of the world are also found in the Karakoram range. Between the Karakoram and the Himalayas in the south and the Kunlun in the north lies the Tibetan plateau. Between the Kunlun and the Tien Shan in the further north lies the Tarim basin. In between the Tien Shan in the west and the mountain chains of north-east Siberia lie the ancient fold mountain ranges-the Altai, the Yablonoi and the Stanovoi-which house the Tarim basin and the vast cold desert of Gobi.
The Southern Plateaus lie to the south of the Central Mountains. Formed of very old rocks, the Southern Plateaus (comprising the plateau of Arabia, the Deccan plateau and the plateau of Yunnan) constitute the major part of the peninsulas projecting southward from mainland Asia. The Great River Valleys lie in-between the mountains and plateaus. Some of these river systems-the Tigris-Euphrates, the Indus, the Ganga-Brahmaputra, the Ayeyarwaddy, the Mekong, the Sikiang, the Chang Jiang (Yangtze-Kiang) and the Huang He-are very old. The Yangtze is Asia's longest river.
Three major island groups are located to the southeast and east of Asia-Indonesia, the Philippines and Japan. Most of these islands have a mountainous core surrounded by narrow coastal plains. Some islands still have active volcanoes.
Asia's coastline measures about 129,077 km.
Because of its tremendous size and varied physical
features, Asia experiences a variety of climates-the bitter cold of the polar north; the hot, dry desert environment of the centre and the southwest; and the hot, humid conditions of the tropical south.
Distribution of Continents and Oceans
About 71 per cent of the globe is water and about 29 per cent is land surface. The continents into which the land surface is broadly divided are: Asia, Africa, North America, South America, Europe, Australia, and Antarctica. If the seas were to drain away, it appears that broad areas lying close to continental shores are actually covered by shallow water less than 180 m deep. Disregarding the earth's curvature, the continents can be visualised as platform-like masses; the oceans as broad, flat-floored basins. Most of the land surface of the continents is less than 1 km above sea-level, while a predominant part of the ocean floor lies between 3 and 6 km below sea level.
Relief features of continents are being discussed here, while those of oceans will be dealt with in a separate chapter Ocean and Oceanography.
RELIEF FEATURES OF CONTINENTS
The continents consist of two fundamental kinds of geological units: (i) the shields, and (ii) the mountain belts or orogenic belts.
The shields are extensive, rigid and permanent part of the earth's crust, composed of Precambrian rocks (more than 590 million years old). These are the oldest rocks on the earth's surface. The mountains of earlier periods were eroded to their roots. The shields today are, therefore, largely plains and low plateaus and are highly stable parts of the earth's continental crust. Crustal movement of
1. Laurentian Shield 2. Brazilian Shield 3. Baltic Shield
4. African Shield
5. Arabian Shield
6. Siberian Shield 7. Deccan Shield
8. China Shield
9. Austra.lian Shield
shields in the later geologic time have been epeirogenic movements, i.e., rise and fall of the crust over broad areas without breaking or bending the rocks. Negative epeirogenic movement resulted in submerging of shields, shallow seas and continental shelves. Later, positive epeirogenic movement brought the sedimentary cover that had gathered over time above sea level where it has been carved up by streams into hills and plateaus. The Canadian Shield in North America and the Russian-Baltic Shield of Europe are well-known shields of the northern hemisphere. Similar shield areas occupy parts of Australia, Africa, South America, India and Antarctica. Rocks in these areas date back to the oldest geological time from one to three billion years ago.
Mountain belts of continents are along narrow a genic zones in which crust has been compressed and fon to buckle into tight folds and at the same time to
strongly elevated. The older, inactive mountain ranges he usually been reduced to hill belts. In some places, they i still moderately elevated possessing a rugged relief. 1 young ranges are still active zones of crustal deformati and volcanic activity in some areas. They rise as speetacu alpine mountains.
Relief features of continents are being discussed here, while those of oceans will be dealt with in a separate chapter Ocean and Oceanography.
RELIEF FEATURES OF CONTINENTS
The continents consist of two fundamental kinds of geological units: (i) the shields, and (ii) the mountain belts or orogenic belts.
The shields are extensive, rigid and permanent part of the earth's crust, composed of Precambrian rocks (more than 590 million years old). These are the oldest rocks on the earth's surface. The mountains of earlier periods were eroded to their roots. The shields today are, therefore, largely plains and low plateaus and are highly stable parts of the earth's continental crust. Crustal movement of
1. Laurentian Shield 2. Brazilian Shield 3. Baltic Shield
4. African Shield
5. Arabian Shield
6. Siberian Shield 7. Deccan Shield
8. China Shield
9. Austra.lian Shield
shields in the later geologic time have been epeirogenic movements, i.e., rise and fall of the crust over broad areas without breaking or bending the rocks. Negative epeirogenic movement resulted in submerging of shields, shallow seas and continental shelves. Later, positive epeirogenic movement brought the sedimentary cover that had gathered over time above sea level where it has been carved up by streams into hills and plateaus. The Canadian Shield in North America and the Russian-Baltic Shield of Europe are well-known shields of the northern hemisphere. Similar shield areas occupy parts of Australia, Africa, South America, India and Antarctica. Rocks in these areas date back to the oldest geological time from one to three billion years ago.
Mountain belts of continents are along narrow a genic zones in which crust has been compressed and fon to buckle into tight folds and at the same time to
strongly elevated. The older, inactive mountain ranges he usually been reduced to hill belts. In some places, they i still moderately elevated possessing a rugged relief. 1 young ranges are still active zones of crustal deformati and volcanic activity in some areas. They rise as speetacu alpine mountains.
Distribution of Continents and Oceans
About 71 per cent of the globe is water and about 29 per cent is land surface. The continents into which the land surface is broadly divided are: Asia, Africa, North America, South America, Europe, Australia, and Antarctica. If the seas were to drain away, it appears that broad areas lying close to continental shores are actually covered by shallow water less than 180 m deep. Disregarding the earth's curvature, the continents can be visualised as platform-like masses; the oceans as broad, flat-floored basins. Most of the land surface of the continents is less than 1 km above sea-level, while a predominant part of the ocean floor lies between 3 and 6 km below sea level.
Relief features of continents are being discussed here, while those of oceans will be dealt with in a separate chapter Ocean and Oceanography.
RELIEF FEATURES OF CONTINENTS
The continents consist of two fundamental kinds of geological units: (i) the shields, and (ii) the mountain belts or orogenic belts.
The shields are extensive, rigid and permanent part of the earth's crust, composed of Precambrian rocks (more than 590 million years old). These are the oldest rocks on the earth's surface. The mountains of earlier periods were eroded to their roots. The shields today are, therefore, largely plains and low plateaus and are highly stable parts of the earth's continental crust. Crustal movement of
1. Laurentian Shield 2. Brazilian Shield 3. Baltic Shield
4. African Shield
5. Arabian Shield
6. Siberian Shield 7. Deccan Shield
8. China Shield
9. Austra.lian Shield
shields in the later geologic time have been epeirogenic movements, i.e., rise and fall of the crust over broad areas without breaking or bending the rocks. Negative epeirogenic movement resulted in submerging of shields, shallow seas and continental shelves. Later, positive epeirogenic movement brought the sedimentary cover that had gathered over time above sea level where it has been carved up by streams into hills and plateaus. The Canadian Shield in North America and the Russian-Baltic Shield of Europe are well-known shields of the northern hemisphere. Similar shield areas occupy parts of Australia, Africa, South America, India and Antarctica. Rocks in these areas date back to the oldest geological time from one to three billion years ago.
Mountain belts of continents are along narrow a genic zones in which crust has been compressed and fon to buckle into tight folds and at the same time to
strongly elevated. The older, inactive mountain ranges he usually been reduced to hill belts. In some places, they i still moderately elevated possessing a rugged relief. 1 young ranges are still active zones of crustal deformati and volcanic activity in some areas. They rise as speetacu alpine mountains.
Relief features of continents are being discussed here, while those of oceans will be dealt with in a separate chapter Ocean and Oceanography.
RELIEF FEATURES OF CONTINENTS
The continents consist of two fundamental kinds of geological units: (i) the shields, and (ii) the mountain belts or orogenic belts.
The shields are extensive, rigid and permanent part of the earth's crust, composed of Precambrian rocks (more than 590 million years old). These are the oldest rocks on the earth's surface. The mountains of earlier periods were eroded to their roots. The shields today are, therefore, largely plains and low plateaus and are highly stable parts of the earth's continental crust. Crustal movement of
1. Laurentian Shield 2. Brazilian Shield 3. Baltic Shield
4. African Shield
5. Arabian Shield
6. Siberian Shield 7. Deccan Shield
8. China Shield
9. Austra.lian Shield
shields in the later geologic time have been epeirogenic movements, i.e., rise and fall of the crust over broad areas without breaking or bending the rocks. Negative epeirogenic movement resulted in submerging of shields, shallow seas and continental shelves. Later, positive epeirogenic movement brought the sedimentary cover that had gathered over time above sea level where it has been carved up by streams into hills and plateaus. The Canadian Shield in North America and the Russian-Baltic Shield of Europe are well-known shields of the northern hemisphere. Similar shield areas occupy parts of Australia, Africa, South America, India and Antarctica. Rocks in these areas date back to the oldest geological time from one to three billion years ago.
Mountain belts of continents are along narrow a genic zones in which crust has been compressed and fon to buckle into tight folds and at the same time to
strongly elevated. The older, inactive mountain ranges he usually been reduced to hill belts. In some places, they i still moderately elevated possessing a rugged relief. 1 young ranges are still active zones of crustal deformati and volcanic activity in some areas. They rise as speetacu alpine mountains.
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