explain the theory of continental drift
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The theory of continental drift
Wegener thought all the continents were once joined together in an "Urkontinent" before breaking up and drifting to their current positions. But geologists soundly denounced Wegener's theory of continental drift after he published the details in a 1915 book called "The Origin of Continents and Oceans." Part of the opposition was because Wegener didn't have a good model to explain how the continents moved apart.
Though most of Wegener's observations about fossils and rocks were correct, he was outlandishly wrong on a couple of key points. For instance, Wegener thought the continents might have plowed through the ocean crust like icebreakers smashing through ice.
"There's an irony that the key objection to continent drift was that there is no mechanism, and plate tectonics was accepted without a mechanism," to move the continents, said Henry Frankel, an emeritus professor at the University of Missouri-Kansas City and author of the four volume "The Continental Drift Controversy" (Cambridge University Press, 2012).
Although Wegener's "continental drift" theory was discarded, it did introduce the idea of moving continents to geoscience. And decades later, scientists would confirm some of Wegener's ideas, such as the past existence of a supercontinent joining all the world's landmasses as one. Pangaea was a supercontinent that formed roughly 200 to 250 million years ago, according to the U.S. Geological Survey (USGS) and was responsible for the fossil and rock clues that led Wegener to his theory. [Have There Always Been Continents?]
Answer:
Alfred Wegener 1880-1930 a German meteorologist and geologist, was the first person to propose the theory of continental drift. In his book, Origin of Continents and Oceans, he calculated that 200 million years ago the continents were originally joined together, forming large supercontinent. He named this supercontinent Pangaea, meaning All-earth.
The Earth's crust is not a single continuous layer. It is made up of a number of gigantic pieces like a huge jigsaw puzzle.
Each piece is called a crustal plate. Currents of molten rock rise up through the mantle like boiling water in a saucepan.
These form convection cells that drive the movement of the plates so that they are continuously moving away or towards each other. Geologically, the most important things happen at the plate boundaries, including most of the earthquakes, volcanoes, igneous rocks, major metamorphism, and mountain building processes.