Mountains and Mountain Building

About this topic

Mountains are landforms rising high above their surroundings, and they form through powerful forces inside Earth. Fold mountains form where plates collide and crumple rock layers (Himalayas, Alps, Andes); fault-block mountains where crust is lifted along faults (Sierra Nevada); volcanic mountains where magma erupts (Mount Fuji, Mount Kilimanjaro); and dome mountains where magma pushes up the crust.

A vivid illustration is the Himalayas: India, carried north on its plate, has been pushing into Asia for about 50 million years. Neither plate sinks easily because both are continental, so the crust crumples and thickens, and Everest still rises a few millimetres each year while erosion works to wear it down. Mountains rise through uplift and are lowered by weathering, glaciers and rivers, so their shape tells a story of competing forces.

Mountains affect climate, creating rain shadows, with wet windward and dry leeward slopes. Climate changes with altitude, so ecosystems form zones, from forest to alpine meadow to bare rock and snow. They store water as snow and ice, which feeds major rivers, provide minerals, and attract tourism, though they pose hazards like avalanches and landslides. A common misconception is that mountains are permanent and unchanging; in reality they are always being built and eroded, just very slowly.