Problems with Wegener's Model of Continental Drift
Wegener's model was not accepted by all geologists. Some thought
that dispersion by winds or ocean currents could explain the distribution
of fossil species. Other geologists thought the poles might wander and
continents remain stationary. Many geologists thought Wegener's evidence
was insufficient.
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.
A mechanism to move continents was proposed by Arthur Holmes,
Scottish geologist in 1928. He believed heat trapped in the Earth caused
convection currents, areas where fluids beneath the Earth's crust rise,
flow laterally, and then fall. The currents would rise beneath
continents, spread laterally, then plunge beneath the oceans.
(Geologists now know that solid rock, not fluids, convect in the
mantle). Unfortunately, Wegener died in 1930 while exploring the
Greenland ice cap. He never had the opportunity to adapt Holmes' ideas
to his views of continental drift.
