The answer is subduction. In locations around the world, ocean crust subducts, or slides under, other pieces of Earth's crust. The boundary where the two plates meet is called a convergent boundary.

The Cascadia subduction zone, where the oceanic Juan de Fuca plate ... Figure 4: Schematic cross-section of the northern Cascadia convergent margin at southern Vancouver Island. The plate boundary ...

For more on divergent boundary, go to The Sea Floor Spread. Also known as subduction boundary, a convergent boundary occurs where one plate slides under another as the two are pushed together.

In regions of convergence, one plate can sink under another in a subduction zone, or two colliding plates can form a mountain belt. At divergent boundaries, plates move away from each other and ...