Composition of the earth
According to science, the earth was a ball of burning gases billions of years ago. Gradually, it cooled down and rocky land and water were formed.
The earth is made up of three layers-crust, mantle and core. Crust is the first layer of the earth. Mantle is made up of very hot rocks. It is so hot the rocks melt into liquid. Sometimes, this very liquid comes out from the cracks in the crust. This hot liquid rock is called lava.
Below the mantel is the `core’. The core is the innermost part of the earth. It mostly made up of iron. The inner part of the core is solid while the outer part is liquid.
The earth spins like a top from west to east. It spins on it’s the earth. This line joins the poles of the earth; the spinning of the earth is called rotation. The earth takes 24 hours to complete on rotation. Day and night are caused due to the rotation of the earth. Do you know how? The earth is rotating all the time. When half of its part is lit by the sun, the other half remain away from the sun. The part which receives the sunlight has day, while the one whish is way from the sun and is in the dark, has night. Due to the rotation of the earth, each part experience day and night, in runs.
The earth also revolves round the sun in its orbit. This movement is called revolution. The earth completes its one revolution in 365 -1/4 days. The revolution causes seasons. The earth has been divided into two equal halves by an imaginary line.
The earth is made up ¾ of water. Water is an important natural resource. Just as we need air to breathe, no living thing-animals or plant can survive for long with out water. We require for drinking and other domestic purposes, for irrigation and for various industrial purpose.
Our India
Total land
The total land area under India is divided into 30% mountainous region, 27% plateau region and 43% plain region. Plains are most suitable for agriculture. The mountains and plateaus are rich in minerals as well as vegetation. Thus there is a difference in the economic activities of the people of different region. This has resulted in varying economic developments. Population is also the thickest in the river valleys and Plains Indian’s originals forest cover has been drastically depleted. Although efforts have brought about a slight increase, we are still far behind the recommended norm of 33%. Indian has only 22% of its total land area under forests.
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