Most active divergent plate boundaries occur between oceanic plates and exist as mid-oceanic ridges.

When these two plates meet, one of them (usually the oceanic plate) goes under the continental plate.

The oceanic plate is saturated with water, and volatiles such as water drastically lower the melting point of the mantle.

This means that an oceanic plate started to dive beneath the North American plate.

Eventually it returns to the air as oceanic plates subduct in plate tectonics.

The location where the two oceanic plates actually meet become deeper and deeper creating trenches with each successive action.

After listening to separate talks from Fred on plate tectonics, looking at the thermal structure of oceanic plates as they formed and cooled.

This large oceanic plate was consumed at subduction zones.

They are formed when one oceanic plate under Japan subducts beneath another ocean plate.

The western edge of the North American continent was later pushed against the oceanic plate under the adjacent ocean.