Andes — the mountain range of western South America

Geology and formation

The Andes were built primarily by the ongoing subduction of the oceanic Nazca Plate beneath the continental South American Plate. This convergent tectonic activity has produced uplift, folding and thickening of the crust along with widespread volcanic activity. Volcanism and earthquakes remain common features of the chain; many high peaks are volcanic in origin. The range includes both ancient metamorphic cores and younger volcanic edifices, reflecting a complex tectonic history that continues today.

Peaks and hydrology

The highest summit in the Andes is Aconcagua, which rises to about 6,962 m above sea level. Other prominent Andean summits include volcanoes and non-volcanic massifs across the belt. The eastern slopes of the mountains feed major river systems: many tributaries that become the Amazon have their headwaters in Andean highlands, and Andean glaciers and wetlands are crucial freshwater sources for downstream ecosystems and cities.

Ecology and highland environments

Because the range runs through many latitudes and rises from sea level to high peaks, the Andes display pronounced altitudinal zonation. Vegetation changes with elevation from coastal deserts and lowland forests to cloud forests, montane woodlands, and high-elevation grasslands such as puna and páramo. These varied habitats support distinctive wildlife, including camelids (llama, alpaca, vicuña) and the Andean condor, and host numerous endemic plant and animal species adapted to steep climatic gradients.

Human history and economy

Human societies have occupied Andean environments for millennia. Complex pre-Columbian civilizations, most notably the Inca empire, engineered terraces, irrigation and road systems adapted to steep slopes. Today the Andes remain densely inhabited in many regions and are economically important for mining, agriculture (potatoes, quinoa and highland tubers), hydropower and tourism. High-altitude archaeological sites and mountain treks attract international visitors while many communities maintain traditional livelihoods and cultural practices.

Notable facts

• The Ecuadorian peak Mount Chimborazo is an eroded volcano whose summit is the point on Earth farthest from the planet's center because of the equatorial bulge; it is classified as an inactive volcano.
• Andean glaciers, though smaller than those in polar regions, are key water reserves and have been sensitive to climate variations.
• The Andes influence continental climate patterns, acting as a barrier to moisture and shaping rainfall distribution on both their windward and leeward sides.

For readers seeking maps, geological overviews or cultural histories, consult specialized atlases and regional studies that treat individual Andean countries and ecosystems in greater detail. Additional resources and databases provide updated information on seismicity, glacier change and biodiversity inventories for Andean regions.