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How does subduction create mountains along continental margins?

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A car drives along the Trans-Canada Highway with Mount Sir Donald's sharp, snow-capped peak rising above forested slopes in the Selkirk Mountains, British Columbia. — mountain Mount Sir Donald in the Selkirk Mountains, British Columbia, looms above a segment of the Trans-Canada Highway.

Mountain building at continental margins occurs primarily through the subduction of an oceanic plate beneath a continental plate, a process that creates mountains through several mechanisms.12

As the subducting slab descends, it reaches depths where heat and pressure drive off volatile components, triggering partial melting in the overlying mantle wedge. This generates magma that rises through the continental crust, forming a volcanic arc inland. This magmatism warms and weakens the crust, making it susceptible to deformation.31

Uplift often occurs in discrete episodes, frequently driven by intervals of stronger plate convergence that squeeze this thermally weakened crust upward. Additionally, mountain belts at these margins are often built by the accretion of terranes—small crustal fragments, island chains, or oceanic ridges—that are scraped off the subducting plate and added to the continental edge. Over time, these processes can create massive mountain ranges, such as the Andes or the Cordilleran belt, which are further supported by the buoyancy of thickened crustal roots.124