Online Notes Our Environment From Chapter 1 Social Science of Class 7
Natural Environment
The natural environment consists of 4 layers-lithosphere, atmosphere, hydrosphere, and biosphere.
- The lithosphere-the lithosphere is the outermost layer of the earth. It is also called crust. The earth crust is made up of different types of rocks. The crustal blocks are of two types-Continental and oceanic blocks. The continental crust lies below the landmass varying 40 km to 100 km in thickness. The oceanic crust lies below the ocean and it is only about 6 km thick.
- Atmosphere-The atmosphere is the layer of air that surrounds the earth. Air is the mixture of gases like nitrogen 78%, oxygen 21% and rest 1% comprises of carbon dioxide and other gases. The layer is thicker at the land surface and thinner at higher levels. The atmosphere helps life to survive on the earth.
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