Landform and Ocean Concepts

(Mountains, Plains and Plateaus are important landforms but the world below the ocean contain a large variety of landforms as well)

Mountains or hills

Himalayan Mountains

Mountains or hills are highly elevated lands, which rise above the surrounding region. When such high hills form a long chain, they are called a mountain range. They may stretch continuously and may occur in a series of parallel ranges, for example, The Great Himalayas. Mountains may be called young or old according to their age. The Alps or the Himalayas are young mountains while the Aravallis or the Appalachian mountains are old mountains. Due to erosion over the years these old mountains have become rounded and low in height. Now they are mere stumps. From the Pamir knot in Central Asia, mountain ranges spread out in different directions. Human habitation is not very dense in high hills because it is difficult to construct communication lines in such mountainous areas.

Plateaus

Tibetan Plateaus

Plateaus are moderately elevated flat-topped lands. They often resemble a table and are also called Tableland. Plateaus rise abruptly from the surrounding areas. They may stretch over thousands of square km. In other words, Plateaus are flat uplands with steep slopes. Laddakh and Deccan are two examples of plateaus. Large parts of Africa, Asia, Australia and North America consist of plateaus. Plateau of Tibet is the highest plateau in the world. Therefore it is called ‘the roof of the world’. Plateaus are moderately populated regions. Transport is not so difficult here as it is in the mountains.

Plains 

North Indian plain

Plains are low-lying and relatively flat stretches of land. They are not very high above the sea level. Rivers, emerging from the mountains carry huge amount of silt, mud, and sand. Rivers carry these materials down to the sea and deposit them along the seacoast or along their banks. The largest plains are found along the river valleys in all the continents, except in Antarctica. Deposits made by rivers consist of sand, silt, and clay. Thus the plains become very fertile. Agriculture all over the world flourishes on such plains, for example the north Indian plain. Construction of transport network is easy. Thus, these plains are very thickly populated regions of the world.

Continents

Extensive masses of land rising above the sea level are called continents. They are generally separated from one another by huge bodies of water. Most of the land area lies in the northern hemisphere. There are seven continents on the earth. They are:

Continents

• Asia
• Africa
• North America
• South America
• Europe
• Australia
• Antarctica

Asia

Asia is the largest continent lies in the northern hemisphere. Our country India situated in this continent. The cold Gobi desert and the Himalayan Mountains are situated in this continent.

Africa 

The second largest continent is Africa. The equator runs almost half way through this continent but does not divide it into equal halves. River Nile, the longest river in the world and the Sahara, the largest desert in the world are situated in this continent. This continent is filled with dense forests and rich in mineral resources.

North America

North America lies entirely in the Northern Hemisphere. It is surrounded by the Atlantic ocean, Arctic ocean and Pacific Ocean. On its west-coast, Rocky mountain, a long chain of mountains is situated.

South America

The major part of South America lies in the southern hemisphere, as little part lies in the northern hemisphere also. River Amazon, world’s largest river and the Andes, longest mountain range of the world situated in this continent. The continent of North America and South America are linked by narrow stretch of land across Panama. 

Europe 

Europe lies to the west of Asia. The Alps mountain range lies in this continent. Europe and Asia are continuous single landmasses. These two continents are separated by the Ural Mountains and the Ural River. These two continents are referred to as Eurasia.

Australia 

Australia is a continent situated in the southern hemisphere. Being the small continent it is often referred to as the ‘Island continent’ as it is surrounded by oceans from all sides. It consists of many islands like New Zealand and Fiji. Fiji Islands and Papua and New Guinea are called Oceanic islands. The Great Barrier Reef is situated the off the east coast of Australia. 

Antarctica

Antarctica is the southernmost continent. The South Pole lies at the Centre of this continent. In size, Antarctica is bigger than Australia and Europe taken together. But, because it is situated in the Antarctic Circle, it remains covered by deep snow throughout the year. Penguins, Seals and other living creatures live in Antarctica. Our country India has set up scientific research stations at Antarctica in the name of Dakshin Gangotri and Maitri. A new research station named Bharati has recently been established.

Oceans

Oceans are vast stretches of water covering a huge area. Unlike the continents oceans are all inter-connected. Therefore, the level of sea water remains same everywhere. This level of water is called sea level. There are four major oceans on the earth. They are pacific ocean, Atlantic Ocean, Arctic Ocean and Indian ocean. The oceans account for about 71 % of the earth’s surface. The average height of the continents is only about 700 meters above sea level whereas the average depth of the oceans is about 4000 meters below sea level. For the matter of convenience, countries divided the vast oceans into seas. For example the sea lies east to India is known as Bay of Bengal and the sea lies west to India is known as Arabian sea.

Oceans

Pacific Ocean

The Pacific Ocean is the largest as well as the deepest ocean. Earth’s deepest part is the Mariana Trench (11022 m deep) and it is situated in the Pacific Ocean. The Pacific Ocean is bounded by Asia and Australia on the one hand and North and South Americas on the other. The volcanic mountains which surrounded the Pacific Ocean are called the Pacific ring of Fire.

Atlantic Ocean

The Atlantic Ocean is the second largest ocean in the world and looks like the letter ‘S’. It is bordered by North and South Americas on the west and Europe and Africa on the east. Hurricanes are very common in this ocean. Its coastline is very much indented. The coastline may be straight or indented in nature. Indented coastlines facilitate the developments of harbors or ports, So Atlantic Ocean is the busiest ocean from the point of view of commerce. 

Indian Ocean 

The Indian Ocean is the third largest ocean in the world, bordered by the continents of Africa in the west, Asia in the north and Australia in the east. India receives rainfall due to the monsoon which originate within this ocean.

Arctic Ocean 

The Arctic Ocean is the smallest ocean in the world. It has North Pole at the Center of the ocean. For most part of the year the ocean remains frozen. This ocean has many icebergs. It is actually a northward extension of the Atlantic Ocean. Arctic Ocean is connected with the Pacific Ocean by a narrow stretch of shallow water known as the Bering Strait. It is bounded by the northern coasts of North America and Eurasia.

Ocean which surround the Antarctica is known as Southern ocean. Actually, this the culmination of South Pacific Ocean, South Atlantic ocean and Indian ocean. Apart from the oceans and seas, there are rivers, lakes, ponds and tanks.

Islands, Archipelago, Peninsula, Strait, Lagoon, Gulf, Bay & Isthmus

• A piece of land surrounded by water on all sides is called an Island. Sri Lanka is an Island country situated south of India. 

  

  Relief features

• A group of islands is termed as Archipelago. Andaman and Nicobar Islands belong to India is a group of islands, hence Archipelago.
• Peninsula is a piece of land that is surrounded by water on three sides. India is also a peninsular country.
• A strait is a narrow stretch of water that separates two large land masses. Palk Strait is a strait between India and Sri Lanka.
• A gulf is a hollow carved out in the sea coast which lets the water reach deep inland. For example the Persian Gulf.
• A lagoon is a shallow body of water separated from a larger body of water by barrier islands or reefs. Lagoons are commonly divided into coastal lagoons and atoll lagoons.
• A Bay is an inlet of the sea with a wider opening than a gulf. For example the Bay of Bengal and the Persian Gulf.
• An Isthmus is a narrow strip of land separating two large water bodies. For example the Isthmus of Panama connects North America with South America.