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How do colliding tectonic plates form mountain ranges?
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mountain
Mount Sir Donald in the Selkirk Mountains, British Columbia,
looms
above
a segment of the Trans-Canada Highway.
Mountain ranges are primarily formed at convergent plate boundaries, where the movement of lithospheric plates leads to intense crustal deformation and uplift. This process, known as orogeny, occurs through several mechanisms:12
- Continent-Continent Collision: When two continents collide, the buoyant continental crust cannot be easily subducted. Instead, the leading edges are scraped off, stacked, and thrust upward, creating high mountain belts like the Himalayas and the Alps. This process often involves ramp overthrusts, where slices of deep crystalline rock are pushed onto the surface of the continent.13
- Subduction-Related Orogeny: At boundaries where an oceanic plate sinks beneath a continent, mountains form through the subduction process itself, often accompanied by volcanic activity and the accretion of crustal fragments (terranes). The Andes serve as a primary example of this type.145
- Terrane Accretion: Small crustal fragments, such as island chains or oceanic ridges, are added to the continental margin as plates converge, contributing to the growth of mountain belts like those found in the North American Cordillera.14
These events are typically characterized by significant folding and faulting of rock strata.4