The greatest shortcoming, at least in the eyes of American geologists, was the lack of an
adequate mechanism for moving the continents. Wegener proposed that the Earth's spin
caused the continents to move, plowing through the oceanic plate and producing mountains
on their leading edges. Geologists at that time understood enough about the strength of
rocks to know that this was highly unlikely. Wegener's work was largely unaccepted in the
northern hemisphere. In the southern hemisphere, where geologists were familiar with
the rocks that Wegener used to support his hypothesis, continental drift was generally accepted.