prize9-3, Exercise 1: Why Wegener was rejected and then vindicated

Model answer (check the details):

Rejected because: his evidence (fit of coasts, matching fossils, rocks and ancient glaciers) was suggestive, but his proposed cause, continents ploughing through ocean floor driven by tides and rotation, was shown to be far too weak. Without a plausible mechanism, many geologists preferred other explanations such as land bridges.

What changed: surveys of the ocean floor in the 1950s and 60s found mid-ocean ridges, very young ocean crust and, with Hess's seafloor spreading idea, a mechanism that moves the sea floor and the continents with it.

Two strongest pieces of evidence: the mirror-image magnetic stripes on either side of ridges (Vine, Matthews and Morley, 1963), and the pattern of earthquakes outlining plates and sinking slabs. Later GPS measurements confirmed movement directly.

Care: say he was right about drift and wrong about the mechanism.