Oceanic subduction

From GeoClasses

Unlike the India-Eurasia collision, while South America is moving westward away from Africa it is not colliding with another continent. Instead it is running into oceanic crust from the Pacific ocean.

This continent-oceanic crust collision also creates a mountain range, the Andes, but it also creates the deep trench that runs along the coast of South America.

Because oceanic crust is denser that continental crust, South America is overriding the oceanic crust, and the Oceanic crust is being subducted beneath the continent. The trench is created where the oceanic crust is being bent down beneath the continental crust.

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