Continental Drift Theory

Topics: Plate tectonics, Seafloor spreading, Continental drift Pages: 7 (2137 words) Published: June 20, 2012
Phase 5 Individual Project
The Sciences: Inquiry, Innovation and Invention
Professor Nicholas Kusina
ToniAnn Santos
Colorado Technical University
May 15, 2012

Alfred Wegener first proposed the theory of “continental drift” in 1915 after finding evidence on continents that had drifted apart, matched very closely when the continents were brought together. Wegener also stated that the fossils found in a particular place often indicated of a possibility that the climate from the region is totally different from today. All of his facts supported the theory of continental drift.

Wegener first suggested that the continents fit together like a jigsaw puzzle and can be pieced together by looking at a map. He named this supercontinent Pangaea, meaning “all land” and suggested that it was surrounded by a supersea, Panthalassa and in the Mesozoic period, Pangaea began to split into separate continents. (Alfred Wegener, 2012) In the late Triassic, Pangaea split into two mega continents, Laurasia and Gondwanaland. In present today, part of Pangaea lies in the Northern Hemisphere and includes North America, Greenland, Europe and Asia, calling this area Laurasia. In the other part of Pangaea we would find South America, Africa, India, Australia and Antarctica, calling this area Gondwanaland. (Williams, 2004)

Other scientists questioned Wegener’s beliefs arguing that the Earth was still adjusting from molten mass, and that lighter rocks such as granite, moved towards the surface, underlain by denser rocks such as basalt. Scientist back then also believed that mountain ranges were produced by the cooling contractions and that the continents and the ocean basins were the end result.

To Wegener, he championed the idea that the lighter granite that made up the continents could move horizontally through the ocean basalt. He argued that if the continents could rise up vertically, they could also move horizontally as well, provided there was sufficient force. Today, we see his findings in the forming of the Rocky Mountains and the Andes, located on the western edges of the Americas. In Japan and the West Indies, you will find island arcs left behind in the wake of drifting continents.

Wegener’s strongest argument was the familiarities of rocks, animals and plants on either side of the Atlantic, stating that the fossils of various plants and reptiles were indigenous to Africa and South America and the living animals that were scattered throughout were hard to interpret unless the continents were once connected. Fossil plants were found in India, South Africa, Australia, Antarctica and South America all similar to each other, suggesting again, that the continents were once combined. Other scientists previously suggested that these were once a bridge of land that connected the continents and then sunk into the ocean. To Wegener, he argued this was not possible stating that if the bridge was made of granite that it could not sink and disappear. (Alfred Wegener, 2012) The Theory of Plate Tectonics

Earth’s rocky outer crust solidified over a billion years ago, forming thick plates that drift atop the soft underlying mantle. The plates are made up of rock and drift consistently all over the world, moving both horizontally and vertically. Through a period of time, the plates will also change in size. Overtime the sea level changes, causing the different amounts of earth’s crust to be covered or exposed.

The theory of plate Tectonics was suggested in the 1960’s and explains the movement of Earth’s plates, causing earthquakes, volcanoes, oceanic trenches, the formation of mountain ranges and other geologic phenomenon. These plates move at an estimated 1 to 10 cm per year and causing seismic activity when plate boundaries interact. There are different types of plate movement that also support the theory of plate tectonics: * Divergent Plate Movement: Sea floor spreading occurs when two oceanic plates move away from...
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