| Age | Billions of years old |
| Type | |
| Impact | Shaping the modern world in various ways |
| Features | Diverse geological structures, unique ecosystems |
| Formation | Tectonic, volcanic, and erosional processes |
| Importance | Influence on cultures, economies, and civilizations • Providers of natural resources • Centers of biodiversity • Barriers to travel |
Mountains are large natural elevations of the Earth's surface rising abruptly from the surrounding level. Formed through complex geological processes over billions of years, mountains display a remarkable diversity of shapes, heights, and compositions across the planet. These imposing landforms have had a profound influence on the development of human civilization, serving as barriers, resources, and centers of unique cultures and environments.
The world's mountains arose through a variety of tectonic and volcanic processes operating over immense stretches of geologic time. In this timeline, mountain building began far earlier than in our own, with the first major uplifts occurring over 3 billion years ago as continental drift and plate tectonics began to shape the Earth's surface.
Some of the oldest mountain ranges, such as the Barberton Greenstone Belt in Africa and the Pilbara Craton in Australia, formed in the Archean eon and feature dramatic, jagged peaks sculpted by intense volcanic and metamorphic activity. Other mountain belts like the Ural Mountains of Eurasia and the Appalachian Mountains of North America arose later in the Proterozoic and Paleozoic eras as the continental landmasses collided and rifted apart.
Volcanic mountain chains like the Cascade Range of North America, the Andes Mountains of South America, and the Japanese Alps were formed more recently, during the Mesozoic and Cenozoic eras, by the subduction of tectonic plates and the upwelling of molten magma. These ranges are characterized by towering, often snow-capped peaks and steep, craggy slopes.
Erosion by wind, water, and glacial ice has also played a major role in sculpting mountain landscapes over time, carving valleys, cirques, and other dramatic features. The resulting diversity of geological formations - from volcanic plugs to glacial moraines - provides habitats for a wide array of plant and animal life.
The Earth's surface is dominated by several major mountain ranges, each with its own distinct geological origins, climates, and ecosystems:
The Himalayan Mountains of Asia, including peaks like Mount Everest, formed by the collision of the Indian Plate and the Eurasian Plate. This young, seismically active range features some of the world's tallest mountains.
The Andes Mountains of South America, running the length of the continent's western coast, arose from the subduction of the Nazca Plate under the South American Plate. Their diverse environments range from tropical rainforests to barren, windswept peaks.
The Rocky Mountains of North America, formed by the uplift and faulting of the continental interior, encompass a wide variety of landscapes from the boreal forests of Canada to the deserts of the American Southwest.
The Atlas Mountains of North Africa, shaped by the collision of the African Plate and the Eurasian Plate, feature a unique blend of Mediterranean and Saharan ecosystems.
The Great Dividing Range of Australia, the country's principal mountain system, was formed by the rifting of the Australian Plate from Antarctica and the Pacific Plate. It supports a variety of endemic plant and animal species.
Due to factors like altitude, latitude, precipitation, and geology, mountain environments harbor some of the most diverse and unique ecosystems on the planet. High-altitude zones are typically dominated by hardy, low-growing vegetation like alpine meadows, cushion plants, and krummholz forests. Lower mountain slopes and valleys often support dense temperate or tropical forests.
Mountain wildlife also displays remarkable adaptations, from the thick fur of snow leopards and Himalayan brown bears to the efficient respiratory systems of Andean condors and alpine ibex. Glacial meltwater flowing from mountaintops provides a vital source of freshwater for downstream communities and ecosystems.
Mountains have also played a crucial role in the development of human civilization, serving as barriers, trade routes, and cultural centers. Many of the world's oldest settlements and empires arose in mountainous regions, and distinct mountain-dwelling cultures have flourished for millennia. Mountains have also been a focus of religious, artistic, and recreational significance throughout history.
Today, mountain environments face a number of existential threats, from deforestation and mineral extraction to the impacts of climate change on glaciers and wildlife. Protecting these unique and vital landscapes remains an important challenge for the global community.
