Continental drift
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Continental drift

One of the major scientific discoveries of the 20th century was made by Alfred Wegener (1880–1930), a meteorologist who began to formulate the theory of continental drift 100 years ago (starting in 1912). This theory posits that the earth’s crust is divided into plates, a little like the broken shell of an egg, and that these plates drift on masses of rock in the earth’s hot mantle that slowly move through convection.

One of the major scientific discoveries of the 20th century was made by Alfred Wegener (1880–1930), a meteorologist who began to formulate the theory of continental drift 100 years ago (starting in 1912). This theory posits that the earth’s crust is divided into plates, a little like the broken shell of an egg, and that these plates drift on masses of rock in the earth’s hot mantle that slowly move through convection. These plates are distinct from the continents themselves, and their edges are more often than not under the oceans. The current shapes of the continents are signs of their arrangement long in the past, with the most famous example being the interlocking of eastern South America with western Africa.

Wegener’s ideas were poorly received at the time, and it wasn’t until the 1960s that his theory became widely accepted in the scientific community, in particular thanks to the work of Canadian geologist John Tuzo Wilson (1908–1993). Wilson discovered a coherent mechanism (hotspots) to explain the formation of the Hawaiian-Emperor seamount chain, of which the Hawaiian Islands are a part. He also contributed to an understanding of the expansion of the ocean floor near mid-ocean ridges. Finally, Wilson described the three broad categories of tectonic plate boundaries: convergent, divergent, and transform.

The study of the earth’s geography and the changes it has undergone is essential to understand and appreciate the scope of the biosphere we have today. We now know that every 200 or 300 million years, the landmasses (continents) come together to form a “supercontinent.” This is known as the “Wilson Cycle.”

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