Subduction zones occur where one tectonic plate slides under another, usually around the Ring of Fire. Convection currents in the mantle cause rocks to rise and fall, powering plate tectonics at the Asthenosphere. Continental drift is when tectonic plate movements cause continents to shift positions over time, an idea first proposed by Alfred Wegener based on matching coastlines, shared rock types, and fossil evidence between continents that were once joined together in the supercontinent Pangaea.