Understanding the Movement of Earth
Continental drift is the idea that continents move freely over Earth’s surface, changing their positions relative to one another over time. This hypothesis has been around for more than 130 years. It’s amazing to know that once ago these continents on Earth were once joined together and have split and moved apart from one another. In 1596, Abraham Ortelius hypothesized that continents “drift”, but later a German meteorologist named, Alfred Wegener, fully developed the idea.
In the early 1900’s, Wegner first proposed the theory of continental drift. He hypothesized that there was a giant super continent name Pangea, meaning “All-earth (Paleontology and Geology glossary, 1996).” During the Jurassic Period Pangea started to break apart. It then formed two smaller supercontinents called Laurasia and Gondwanaland. “Laurasia was the northern supercontinent, containing what is now North America and Eurasia (excluding India). Gondwanaland was the southern supercontinent, composed of all the present-day Southern Hemisphere continents and India (which has drifted north) (Plummer, Carlson, & Hammersley, 1937).” He based his idea upon 4 different types of evidence: Fit of the Continents, Fossil Evidence, Rock Type and Structural Similarities, and Paleoclimatic Evidence. “In the 1960’s, it was recognized that the fit of the continents could be even further improved fitting the continents at the edge of the continental slope – the actual extent of the continental crust (Continental Drift).” Wegner also identified fossils were located on continents that were widely separated. At some point Wegner’s idea of continental drift was accepted because no one could come up with a reasonable mechanism on how the continents actually moved. Seafloor spreading is a theory that was proposed by Harry Hess in the 1960’s. “It is the hypothesis that the sea floor forms at the crest of the mid-oceanic ridge, then moves horizontally away from the...
Bibliography: Continental Drift. (n.d.). Retrieved 2011, from Continental Drift: http://www.sci.csuhayward.edu/~lstrayer/geol2101/2101_Ch19_03.pdf
Paleontology and Geology glossary. (1996). Retrieved 2010, from Enchanted Learning: http://www.enchantedlearning.com/subjects/dinosaurs/glossary/Contdrift.shtml
Plummer, C. C., Carlson, D. H., & Hammersley, L. (1937). Plate Tectonics. In C. C. Plummer, Physical Geology (pp. 485-86). McGraw Hill.
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