Continental Drift

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by simpson17018
Last updated 7 years ago

Discipline:
Science
Subject:
Geostudies
Grade:
9

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Continental Drift

CONTINENTAL DRIFT

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What is Continental Drift?

Geologist’s current understanding of Continental drift is similar to Wegener’s theory with minor changes to improve accuracy. The Vine-Matthews-Morley hypothesis confirmed Hess’s seafloor-spreading hypothesis, and also helped to confirm Wegener’s continental-drift theory. Text 8 states, “Vine-Matthews-Morley hypothesis made predictions about magnetic field orientations in ocean-floor rocks based on the idea that Earth’s magnetic field flipped its orientation through time.” This in turn helped to support Wegener’s hypothesis, meaning it was accepted as fact in the modern world. Fred Vine (Text 9) states that “the post-war investment in marine geology and geophysics paid off in the form of providing compelling evidence for seafloor spreading and hence continental drift. By the late 1960s the vast majority of geologists and geophysicists were convinced that continental drift was a reality.” This demonstrates how overtime society has come to accept the Continental Drift theory as fact through extensive investigation. These investigations helped to provide a better understanding of plate tectonics and the movement of the continents.

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The German scientist Alfred Wegener (1880-1930) suggested in his Continental Drift theory that perhaps all landmasses had once been joined together. Wegener implied that over time this landmass divided and continents floated on the ocean floor to the positions they are in today. As the primary source of Wegener’s writings demonstrates he directly suggests that “the continents must have shifted. South America must have lain alongside Africa and formed a unified block which was split in two”. Wegener’s hypothesis was mostly based on matching coastlines of continents, and the similarity of fossils and rock types on continents that are separated by oceans. In his research, he lacked explanation of the mechanism that allowed Continental Drift to occur. Frankel in 1988 in his secondary source (Text 7) detailed how sea floor spreading benefited and supported Wegner’s theory. ‘It came from marine geology, another relatively young field. By the early 1960s…special attention was directed towards the origin of ocean ridges.’ As seen in the image below, seafloor spreading is a process that occurs at mid-ocean ridges, where new oceanic crust is formed through volcanic activity and then gradually moves away from the ridge. Seafloor spreading helped explain and ultimately prove the validity of the continental drift theory.

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Before the emergence of Wegener’s Continental Drift theory, most physicists and geologists were of the view that mountains and other features on the Earth’s surface were created because the Earth was shrinking over time. As seen below, this theory can be explained by the image of the shrivelled apple. It was suggested that as the Earth cooled, a skin of crust formed. As a result of the molten ball cooling the Earth shrunk, causing the crust to buckle, much like how an apple shrinks and wrinkles as it dries in the sun. This theory could not explain the presence of fossils in high places, such as the Alps. The theory also predicted that volcanoes and mountain ranges occur randomly worldwide, an idea that we now know is false. When Wegener’s theory came to existence it contradicted these previously held beliefs. According to the reputable United States Geological Survey (Text 2), “ … at the time Wegener introduced his theory, the scientific community firmly believed the continents and oceans to be permanent features … Not surprisingly, his proposal was not well received….” This demonstrates how more evidence was needed to support the Continental Drift theory.

By Emma Simpson

Before Continental Drift

Wegener's Theory

Conclusion

(Simpson, 2013)

(Big History, 2013)

(Simpson, 2013)

(Colonial Mail, 2010)

Current Understanding


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