Depending on their type of formation, mountains are of four types. First, the folded mountains, which are made up of rock layers, squeezed by great pressure into large folds. Examples of this kind are the Appalachian and the Alps Mountains.
Second, Dome Mountains where the rock layers were forced up by lava coming with great pressure from below the Earth’s surface. Examples of these are the Black Hills of South Dakota.
Third are the Block Mountains, which are formed as a result of breaks or faults in the Earth’s crust. Examples of such are the Sierra Nevada Range of California.
The last are Volcanic Mountains, which are made up of lava, ash and cinders poured out from within the Earth. The examples include Mount Ranier in the United States, and Fujiyama in Japan.
At the same time, Rocky Mountains were formed through all the above processes.
Below Mountains info from Wikipedia (Read More):-
A mountain is a large landform that stretches above the surrounding land in a limited area usually in the form of a peak. A mountain is generally steeper than a hill. The adjective montane is used to describe mountainous areas and things associated with them. The study of mountains is Orology. The 50 tallest mountains in the world are in Asia.
http://en.wikipedia.org/wiki/Mountains
