What were the two choices wegener saw concerning climate zones of the past?

Alfred Wegener was a German meteorologist who was the founding father of the theory of continental drift.  As far as climate was concerned, Wegener found glacial deposits, the remains of drifts of debris compiled by glacial action in tropical areas of the earth, where it was much too warm for glaciers to exist.  Likewise, he found the remains of tropical plants and animals that were located in areas much too cold to foster such life forms.  Wegener correctly postulated the continents must have been in different climatic environments at one time.  Then, they drifted, largely by the rotational spin of the earth to their present locations in totally different climates.  Wegener's idea of continental drift had a hard time gaining acceptance among the scientific community, as he had a weak mechanism explaining what could cause large land masses, such as the continents, to drift across large bodies of oceanic water to totally different climatic conditions.

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Argon, carbon-14, and carbon-12