In 1915 the German scientist Alfred Wegener, who had noted a similarity between the geographical shapes of South America and Africa, proposed that all the land masses had at one time been joined into one huge supercontinent. He called this supercontinent Pangea. ---- Wegener did not know of any mechanism that could have caused continental drift. So his idea, although debated initially, was largely ignored.
A) He further suggested that Pangea had subsequently broken apart and that various land masses had separated in a process known as continental drift.
B) Earths crust is composed of seven large plates, plus a few smaller ones, that float on the mantle which is the solid layer of Earth lying beneath the crust and above the core.
C) As the plates move, the continents change their relative positions, and this movement of the crustal plates is termed plate tectonics.
D) When two plates grind together, one of them is sometimes buried under the other in a process known as subduction.
E) As the continents began to drift apart, populations became geographically isolated in different environmental conditions and began to diverge along separate evolutionary pathways.