The distant past

The present geography of the Arctic is just a brief snapshot of geologic time (Figure ). In 1912, Alfred Wegener proposed that the Earth's continents were once part of a single supercontinent that he named Pangea (meaning "all lands"). Modern theory explaining continental drift, termed plate tectonics, was developed during the 1960s. The Earth's crust is divided into a number of continental and oceanic plates. Due to convection currents in the mantle, which is heated through radioactive decay, the ocean floors are continually moving, sinking at the edges, spreading from the

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PALEOCENE

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