Mountains and Oceans on the Earth

The crust of the earth is its outer most surface layer which is about 6- 35 km thick. It is not an even surface but forms hollows that are full of water. These are called and ridges and wrinkles that are the great mountain chains. This outer surface of the Earth moves constantly producing the oceans and mountains.

Mountains also keep growing or eroding. But these are very slow processes that take several million years to occur. The vast Himalayan mountain range in Asia began to grow 50 million years ago, but it is so young that it is still being formed. The Aravalli range, in the south west of Delhi and in Rajasthan, is believed to be the oldest mountain range in the world. It is eroding and degenerating.