heavier oceanic plate will dive under the lighter plate at a subduction zone. It will travel downward, like a runaway elevator crashing through a concrete floor, carrying crustal material back into the mantle, where it dissolves. As the descending plate drills into the mantle, it will generate so much friction and heat that it can melt the crust above it, splitting it and punching up new volcanic mountain chains. This is how the Andes formed, as the Pacific plate burrowed beneath the plate carrying the west coast of South America. Finally, there are transform margins. Here, plates grind their
...more
