MOUNTAINS

There are four main types of mountains.

Each type forms in a different way and produces mountains that vary greatly in size.

FAULT-BLOCK MOUNTAINS

The Sierra Nevada Mountains in California

The Teton Range in Wyoming

These are sharp, jagged mountains

They form because of pulling forces (tension)

Huge, tilted blocks of rock are separated from surrounding rock by faults to form these mountains.

FOLDED MOUNTAINS

The Appalachian Mountains in North America

They form because of colliding forces (compression).

Rock layers are pushed together and fold over to form these mountains.

UPWARPED MOUNTAINS

The Adirondack Mountains in New York

The Rocky Mountains in Colorado

The Black Hills in South Dakota

They form when forces inside Earth push up on the crust

VOLCANIC MOUNTAINS

Mount St. Helens in Washington

Mount Popocateptl in Mexico

They form when magma is forced upward and flows onto Earth’s surface

They can form underwater or on land

ISOSTASY

Isostasy is the principle that states that Earth’s crust and lithosphere float on the upper part of the mantle.

This is believed to be the force that keeps mountains elevated above the surrounding land.