Our Changing Earth
The surface of earth is not uniform. We can see a lot of different features around ourselves. We find mountain ranges, deep gorges, plateaus, plains, etc., on the surface of earth. These variations are due to the natural forces acting inside the earth.
The topmost layer of the crust of the earth lithosphere is broken into a number of plates known as the lithospheric plates. The movement of lithospheric plates causes changes on the surface of earth. The main characteristics of lithospheric plates are:
There are currently eight major and many minor plates.
These move around very slowly.
Their movement is circular.
This movement is in turn caused because of the movement of the molten magma inside the earth.
It causes changes on the surface of the earth.
The earth movements are divided on the basis of the forces, which cause them. These forces are of two types:
1. Endogenic Forces - The forces which act in the interior of the earth are the endogenic forces. Endogenic forces are further sub-divided into:
Sudden Forces – These forces act suddenly and change the surface of the earth. Ex – Earthquake, volcanic eruption, etc.
Diastrophic Forces – These forces are very slow and take a long time to change the surface of the earth. Ex – Mountain building, etc.
2. Exogenic Forces - The forces which work on the surface of the earth are the exogenic forces.
The surface of earth is continuously changing by two processes, which are weathering and erosion. These two processes are carried out by the agents like water, wind, ice and sea waves.