Mountains Geology

Mountains — elevated landforms rising steeply from surrounding terrain — form through tectonic plate collisions (fold mountains like Himalayas, Alps, Andes), volcanic activity (Cascades, Andes volcanic arc), or erosion of elevated plateaus (Appalachians, Urals). The Himalayas — still rising 5mm/year as India collides with Eurasia at 5cm/year — contain 10 of the world's 14 peaks over 8,000m ('eight-thousanders'). The Andes (7,000km, longest continental mountain range) hosts Aconcagua (6,961m, highest outside Asia). Mountain ecology: altitude zones produce temperature decrease of 6.5°C per 1,000m, creating a vertical sequence from lowland ecosystems to alpine tundra to permanent snow, equivalent to moving from tropics to polar regions. The rain shadow effect (mountains forcing air upward, causing precipitation on windward side and desert conditions on leeward side — e.g., Atacama Desert in Andes rain shadow, Death Valley in Sierra Nevada rain shadow) creates dramatic ecological contrasts within short distances. Mountains contain 25% of Earth's terrestrial biodiversity and provide water to 1.9 billion people (mountain glaciers as water towers). Mountain cultures (Tibetans, Andean peoples, Swiss, Berbers) have developed specific physiological and cultural adaptations to altitude.