CONTINENTAL DRIFT

The article...

CONTINENTAL DRIFT


The theory of continental drift explains that the continents are constantly changing position relative to one another. Continental drift is part of a larger theory known as plate tectonics, which describes the processes that result in many of the major geological features on Earth.


Geologists Alfred Wegener and Frank Taylor first proposed the theory of continental drift in 1912. They believed that all of the continents had been joined together in a massive super continent called Pangaea approximately 200 million years ago. They suggested that pieces of Pangaea slowly broke apart and moved into the positions that the continents occupy today.


Wegener and Taylor used several different lines of evidence to support the idea of continental drift. The first involves the simple observation that the modern continents can be assembled so that they fit together like pieces of a puzzle. This idea was actually first mentioned by Sir Francis Bacon more than 300 years earlier. He noticed that the bulge of Africa can fit into a notch in the North American continent and that the bulge in South America where Brazil is located fits in a notch in the continent of Africa.


Wegener also noticed that identical fossil species are found on South America and on Africa. He reasoned that it would be very difficult for many of these plant and animal species to have traveled the great distance across the ocean and that the species must have existed on the same continent at one point in time. In addition, Wegener reasoned that the coal deposits [coal is formed by slow, continual pressure on dead plants] on Antarctica represented fossil plants that must have grown when the continent was located in a more tropical latitude. Finally, Wegener pointed out that the locations of large grooves, called striations, in rocks made by glaciers in South America and Africa are best explained if one assumes that the Atlantic Ocean did not separate the continents.


"Piecing Continents Together." Environmental Issues: Essential Primary Sources. Ed. Brenda Wilmoth Lerner and K. Lee Lerner. Detroit: Gale, 2006. 88-90. Opposing Viewpoints In Context. Web. 14 May 2013.

According to the article above, geologists Alfred Wegener and Frank Taylor used four pieces of evidence to support the theory of continental drift.

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650 Million Years in 1 Min and 20 Sec