From the animation at the left, we can see that the
modern ocean basins formed as a result of the breakup of Pangea and
subsequent drift of the continents. This was the one place where Wegener
was wrong -- he believed that the crust forming the continents plowed through the crust below the
oceans, much like a boat plowing through water.......even in the first half of the 20th century, scientists knew was not possible
-- since the rocks under the seafloor are much
stronger than the rocks that compose the continents (i.e. it would be like
pushing a marshmallow through a block of wood).
As we will see, as the
continents drift apart, new crust is formed beneath the sea to fill the
growing space and to fill the void.
However, Wegener, and others before him, did recognize that there was an
inescapable match between the coastlines across ocean basins - and by cutting
a map into pieces - they could fit the continents back into single