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Laurasia(lôrāzh`ə): see continental driftcontinental drift,
geological theory that the relative positions of the continents on the earth's surface have changed considerably through geologic time. Though first proposed by American geologist Frank Bursley Taylor in a lecture in 1908, the first detailed theory of
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(from “Laurentian Shield,” the former name of the Canadian Shield, and “Asia”), the ancient continent that included the North American, Eastern European, and Siberian platforms, and possibly the Chinese-Korean and South Chinese platforms as well as the Caledonian and Hercynian folded structures located between them. The unification of the North American and Eastern European platforms into a single land mass occurred at the beginning of the Devonian across the area now occupied by the northern part of the Atlantic Ocean. The other parts of Laurasia became joined together by the end of the Paleozoic. The breakup of Laurasia and the formation of the basin of the North Atlantic began in the middle of the Mesozoic.