Jan 19, 2013

Restless Earth

On a world map, the east coastline of South America bears an uncanny likeness to the shape of the west coast of Africa. Look at the edges of the continental shelves of these two continents, a couple of hundred metres under the sea's surface, and the resemblance is even more striking. The two would fit together like pieces of a giant jigsaw. In fact, they once did. The idea of continental drift, once dismissed out of hand, is now well established in science. The major land masses or continents have changed less through time than the Earth's crust under the oceans. The oceanic crust has continually formed new patches from molten rocks welling up from below, while other patches melt back into the depths again. The continents have been carried around like giant rafts on these changing shapes of oceanic crust.

-- Part of the evidence

Evidence for continental drift comes from many areas, including fossils. Remains of the reptile Lystrosaurus have been found in South Africa, Antarctica, India and China, suggesting these lands were joined many years ago.

-- First to propose

The idea of continental drift has been around for centuries. First to propose a scientific explanation was German weather expert Alfred Wegener (1880-1930), in 1912. But political problems, world wars and Wegener’s background in meteorology meant his suggestions were not taken seriously until 1960s. (Adapted from 'World of Science')