One way mountains form is when the tectonic plates of the earth collide, causing the folding up of the earth's crust. there are other ways for mountains to form. another way mountains may form is by

The other ways that mountains may form are through:

a. Magma movement, where the tectonic plate is pushed beneath another that causes magma to be forced upwards or to the surface. This type generally creates volcanic mountains.

b. Rifting, where faults in the crust move past each other, i.e. one side of the fault rises higher than the other side. This type generally creates block mountains. 

c. Erosion, which generally happens during and after an uplift. The newly formed mountain becomes exposed to gravity, water, wind, and depending on the location, ice.