sentence: Subduction is believed to work by density.
sentences_before: Found at the base of some continental slopes, 'ocean trenches' have relatively steepsides falling dramatically to the ocean floor. In geology, subduction is the theoretical process whereby one oceanic plate slides under another crustal plate.
sentences_after: As the heavy plate descends steeply into the earth, the lighter, or less dense, the two plates rides over the edge of the heavier plate.
concept_name: subduction
headings: Oceanic trench
categories: Landforms Oceanography