When Continents Collide

摘要

Geologists mapping seismic activity and underwater topography off the coast of Portugal say the tectonic forces that once split and spread the ancient supercontinent Pangea across the surface of the globe appear to be shifting into reverse, setting our existing continents on an eventual collision course. While constructing a new tectonic map of the area, Monash University geologist Joao Duarte observed an inkling of a fracture in the normally intact and inactive plate that underlies the Atlantic Ocean. Such a fracture, says Duarte, is evidence of an "embryonic subduction zone," where a new edge is formed, then forced under the remainder of the plate, into the Earth's molten mantle.