Fault-block mountains are formed when deep areas of bedrock are broken into faults leaving steep vertical displacements in the Earth's crust.
The vertical motion of dropped blocks and lifted blocks, often accompanied by tilting, creates high, sheer cliffs. These blocks are formed when the Earth's crust is stretched and pulled apart by tectonic forces. There are two types of block mountains: lifted and tilted. Look at the diagrams and click on the tabs below to learn more.
Tilted Block Mountains
Lifted Block Mountains
The tilted block mountains have a gentle slope on one side and a steep slope (scarp) on the other side, such as the Grand Tetons. The tilted faults in the Grand Tetons were caused when swelling underneath the rock broke the rock layers into perpendicular faults.
The lifted block mountains have two steep sides (scarps) and are caused by rock layers being stretched in different directions forming lifted blocks called horsts and dropped blocks called grabens.
