The Rocky Mountains. This part of the chain is in Canada. Towards the left of the picture, running in a north-northwest direction out of the frame, is the Columbia River.

Ranges are formed by folding, faulting and warping of the Earth's crust, and by volcanic activity. The most impressive mountain chains are created near the margins of tectonic plates. The Himalayas, which of course have many of the highest peaks on the planet, are produced by the Indo-European Plate (which incorporates India) pushing into the Eurasian Plate (Asia). As it does so the Eurasian Plate is compressed and is pushed upward. The Swiss Alps were raised by a similar crumpling effect as the African Plate pushed northward against the southwest edge of the Eurasian Plate.

Some of the world's longest chains are formed at destructive plate margins. One of the best examples is where the edge of the Pacific Plate disappears underneath the South American plate along the Peruvian and Chilean coast. The descending plate forms a deep trench (the Peru-Chile Trench) and when it enters the Earth's molten asthenosphere itself is melted. The thickening crust here forms the Andes mountain chain.

At some destructive margins along the west coast of North America and the East coast of Japan, magma from the melted subducted plate rises through the crust to form a range of volcanic mountains parallel with the edge of the plate. These mountains feature steep sided volcanic cones.

Ranges can also be formed when fractured crustal blocks are tilted, or when the Earth's crust is updomed, bent upwards without fracturing, forming dome mountains like the Black Hills of South Dakota.