The formation of mountains is not a sudden process, but the mountains are formed as a result of a long process. This formation of mountains occurred in various mountain – building periods.
There are four periods of mountain – building on the earth’s surface:
1. Archean Mountain Period: This mountain – building movement occurred about 40 million years ago in Cambrian period.
2. Caledonian Mountain Period: This, movement occurred about 32 million years ago.
3. Hercynian Mountain Period: This movement occurred about 22 million years ago.
4. Alpine Mountain Period: This movement occurred about 3 million years ago.
