Continental Drift (SG-01)
Landmasses are not stable. Continents have moved during much of recent geologic time.

All continents we know today were joined in a landmass called Pangaea. In the east the great Ocean of Tethys divided Pangaea into two main sections: the northern, Laurasia; the southern, Gondwanaland. Today the Mediterranean Sea is all that remains of that vast ocean.

About 160 million years ago, the great landmass began to break apart. North America drifted away first. Africa and South America remained in one mass, but Antarctica and Australasia broke away and India began its northward drifting toward Asia. Europe was still joined to North America but was separated from Asia by a shallow sea. Seventy million years ago, the continents were in a modern pattern, although distances be- tween them continued to change. In 1910 Frank B. Taylor, of the U.S. Geological Survey, proposed reconsideration of the continental-d rift theory suggested by Francis Bacon in 1620 and Antonio Snider in 1855. In 1912 German geologist Alfred Wegener presented his continental-drift theory. He became noted for his hypothesis; Taylor did not. Although continental drift was rejected by most scientists for many years, it was greatly enhanced by the concept of sea-floor spreading by Hess of Princeton University in 1960 and plate tectonics by the Frenchman LePichon in 1968.

Our Hoosier State Beneath Us: Structural Geology


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