Because it appeared to fit the facts as far as they could be ascertained (as with any theory).
No, it was not because they thought that he is an idiot.
When German meteorologist Alfred Wegener first published his theory on Pangea (super continent) he was widely ridiculed for it. Some of the reaction to his theory on continental shift and a super continent was actually quite hostile. The idea was first put forward in 1912 but it wasn't until the 1950's that his idea was really rethought. By then evidence of continental drift was starting to support his ideas.
Alfred Wegener was the German scientist who proposed the theory of the supercontinent known as Pangaea.
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When German meteorologist Alfred Wegener first published his theory on Pangea (super continent) he was widely ridiculed for it. Some of the reaction to his theory on continental shift and a super continent was actually quite hostile. The idea was first put forward in 1912 but it wasn't until the 1950's that his idea was really rethought. By then evidence of continental drift was starting to support his ideas.
Alfred Wegener
pangea
Alfred Wegner
It is known as the continental drift theory
Supercontinent was first proposed in 1912 by the German meteorologist Alfred Wegener as a part of his theory of continental drift.
Pangaea .
Continental drift theory