1. Reverse faults: These faults occur when rocks are pushed together (compression), causing the hanging wall to move upwards relative to the footwall. This upward movement creates mountains. The Himalayas are a prime example of mountains formed by reverse faults.

2. Thrust faults: These are a special type of reverse fault where the angle of the fault plane is very low (less than 45 degrees). This shallow angle causes the hanging wall to slide over the footwall, often resulting in large-scale overthrusting. The Appalachian Mountains in the eastern United States are a good example of mountains formed by thrust faults.

These are just two types of faults that can lead to mountain formation. Other processes, such as volcanic activity, can also contribute to the formation of mountains.