Geology of the Himalayas

The geology of the Himalayas concerns the rocks, structures, and processes produced by the collision of the Indian and Eurasian plates, which continues to raise and reshape the range.

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Indian Plate: A tectonic plate carrying the Indian subcontinent and adjoining oceanic crust. Its northward motion drives the ongoing collision that builds the Himalayas.
Lesser Himalaya: A tectonic zone of mostly metamorphic and sedimentary rocks between the Sub-Himalaya and Greater Himalaya. Its rocks and thrust boundaries form a major part of the range’s internal structure.
Tethys Ocean: An ancient ocean that lay between the Indian and Eurasian landmasses before their collision. Its closure preceded the suturing of India to Eurasia.
Himalayan seismic hazard: The risk of damaging earthquakes arising from active faults and accumulated strain in the Himalayas. Fault geometry and convergence rates inform estimates of earthquake potential.
Channel flow model: A model in which weak, partially molten middle crust flows outward beneath an orogenic belt. It explains some high Himalayan structures through crustal flow rather than thrusting alone.
Main Himalayan Thrust: A major, largely buried fault system along which the Indian plate underthrusts the Himalayas. It accommodates much of the convergence beneath the range.
Greater Himalaya: The high Himalayan zone, dominated by deeply buried and metamorphosed continental rocks. Its crystalline rocks record burial and heating during Himalayan crustal thickening.
India–Asia collision: The tectonic convergence and eventual contact of the Indian and Eurasian continental plates. This collision initiated the principal phase of Himalayan mountain building.
Himalayan landslides: Downslope movements of rock, soil, or debris common in the steep Himalayan terrain. Rock structure, earthquakes, rainfall, and road cuts shape landslide susceptibility.
Critical taper theory: A mechanical model describing how a wedge of deforming material maintains a stable surface slope and basal dip. It offers a wedge-thrust explanation for Himalayan fold-and-thrust structures.