A

David

Darling

ocean trench

oceanic spreading

How ocean trenches and mid-ocean ridges are formed
Credit: U.S. Geological Survey.


An ocean trench is a long, narrow, linear depression of the sea floor caused by the subduction of one plate under another. Ocean trenches have a V-shaped cross-section and run, typically, roughly parallel to continental coastal mountain ranges or volcanic island arcs. See also mid-ocean ridge.