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General Awareness play a vital role in all Examination. we can expect Questions from different Topics.In Banking and other competitive exams like RRB, CDS, LIC AO, RBI, SSC, UPSC, FCI, UIIC, OICL, SBI Clerks and PO the questions on CONTINENTS AND OCEANS are being asked. Here we have given Geography study notes on” CONTINENTS AND OCEANS “ for SSC CGL Examinations 2019-20 & other examination. Candidates those who are all preparing for the Examination can use this study material.
The surface of the earth is a complex zone in which three main components of the environment meet, overlap and interact. The solid portion of the earth on which we live is called the Lithosphere. The gaseous layers that surround the earth, is the Atmosphere, where oxygen, nitrogen, carbondioxide and other gases are found.
Water covers a very big area of the earth’s surface and this area is called the Hydrosphere. The Hydrosphere comprises water in all its forms, that is, ice, water and water vapour.
The Biosphere is the narrow zone where we find land, water and air together, which contains all forms of life.
LITHOSPHERE
The solid portion of the earth is called the Lithosphere. It comprises the rocks of the earth’s crust and the thin layers of soil that contain nutrient elements which sustain organisms.
There are two main divisions of the earth’s surface. The large landmasses are known as the continents and the huge water bodies are called the ocean basins. All the oceans of the world are connected with one another.
OCEAN BASINS
Our earth is the only planet in the solar system which has water in abundance, hence, it is often called a ‘watery Planet’. About 71 % of the earth’s surface is covered by water.
Oceans form a single, large, continuous body of water encircling all the landmass of the earth. They account for four- fifth of the Southern Hemisphere and three fifth of the Northern Hemisphere. They contain 97.2 percent of the
world’s total water.
There are four principal oceans in the world which are separated largely on the basis of their geographical locations. These are the Pacific Ocean, the Indian ocean, the Atlantic Ocean and the Arctic Ocean. All the other seas, inland seas or the arms of the oceans, are counted within these four main oceans.
THE RELIEF OF THE OCEAN BASINS
The ocean water conceals a considerable variety of landscape very similar to its counterpart on the continents. There are mountains, basins, plateaus, ridges, canyons and trenches beneath the ocean water too. These relief features found on the ocean floor are called submarine relief. The Ocean basins are broadly divided into four major sub-divisions. They are:
(a) Continental shelf;
(b) Continental slope;
(c) Abyssal plains and
(d) The ocean deeps.
MOVEMENTS OF OCEAN WATERS
The waters of oceans are never still. The oceans actually exhibit three major types of movements – waves, tides and currents.
(I) WAVES
Waves are oscillatory movements that result in the rise and fall of water surface. Infact, the movement of each water particle in a wave is circular. The movement of the waves is just like the wind blowing across a wheat
field and causing wave like ripples to roll across its surface. The wheat stalk returns to its original position after the passage of each wave of wind. Similarly water also returns to its original position after transmitting a wave. A wave has two major parts. The raised part is called the crest. Between the two crests are low areas called troughs. The vertical distance between trough and crest is called wave height. The horizontal distance between two crests
or two troughs is called wave length. The time it takes for two crests to pass a given point is called wave period.
(II) TIDES
Along a coast all over the world, we observe the sea water moving both upwards and downwards at rates varying from place to place. Such a variation in sea level occurs from hour to hour and from day to day.
(III) CURRENTS
The ocean current are horizontal flow of a mass of waters in a fairly defined direction over great distances. They are like stream of water flowing through the main body of the ocean in a regular pattern. The average speed of current
is between 3.2 km to 10 kms per hour. Ocean currents with higher speed are called stream and currents with lower speed are called drift.
Continents
There are seven major continents. These are separated by large water bodies. These continents are – Asia, Europe, Africa, North America, South America, Australia and Antarctica.
Asia is the largest continent. It covers about onethird of the total land area of the earth. The continent lies in the Eastern Hemisphere. The Tropic of Cancer passes through this continent. Asia is separated from Europe by the Ural mountains on the west The combined landmass of Europe and Asia is called the Eurasia (Europe + Asia).
Europe is much smaller than Asia. The continent lies to the west of Asia. The Arctic Circle passes through
it. It is bound by water bodies on three sides.
Africa is the second largest continent after Asia. The Equator or 00 latitude runs almost through the middle of the continent. A large part of Africa lies in the Northern Hemisphere.
The Sahara Desert, the world’s largest hot desert, is located in Africa. The continent is bound on all sides
by oceans and seas.
North America is the third largest continent of the world. It is linked to South America by a very narrow strip of land called the Isthmus of Panama. The continent lies completely in the Northern and Western Hemisphere.
South America lies mostly in the Southern Hemisphere. South America has the world’s largest river, the Amazon. Australia is the smallest continent that lies entirely in the Southern Hemisphere. It is surrounded on all sides by the oceans and seas. It is called an island continent.
Antarctica, completely in the Southern Hemisphere, is a huge continent. The South Pole lies almost at the centre of this continent. As it is located in the South Polar Region, it is permanently covered with thick ice sheets. There are no permanent human settlements. Many countries have research stations in Antarctica. India also has research stations there. These are named as Maitri and Dakshin Gangotri.
