Plate Tectonics
Plate tectonics is a recently developed science, and it can be used to explain a lot of phenomena on the Earth, such as earthquakes. There are actually two big fundamental theories of plate tectonics. One of the basic theories is called continental drift, and the other one is the theory of seafloor spreading. The theory of continental drift can not explain the power source of moving continents, so the theory is not complete. The theory of seafloor spreading is only focusing on the movements under water, and the theory still cannot find the evidence of the power source. After having better understanding the activities of volcanoes, earthquakes and terrestrial magnetism, the theory of plate tectonics was introduced about 30 years ago. The most obvious evidence of continental drifting is the remarkable fit of the South American and African continents. By recombining present continents, the Pangaea is still clearly seen. The graph bellow compares the Pangaea to the present continents.In 1912, Lothar Wegener introduced the theory of continental drift, which based on the evidences of geologic structures and plant and animal fossils. Here are three proofs that support the theory of continental d
PHYSICAL EVIDENCE The most powerful evidence of seafloor spreading is the magnetic striping and polar reversals. Washington, DC: Accents Pubns Service, 1996. There are four types of boundaries:DIVERGENT BOUNDARIES Divergent boundaries usually occur along the spreading center where magmata erupt from the weak spots of crusts. fÜ The coal deposits from identical age in the areas mentions at previous point. fÞ Continental-continental convergence, there are usually high plateaus and mountains between two continental crusts. The following graph shows the theoretical model of the magnetic striping. The graph below is the model of divergent boundary. And the theory of seafloor spreading is derived from those new concepts. At the time when Wegener introduced his theory, there were not enough evidences to show what kind of force can move those giant continents over such a long distance.
Common topics in this essay:
PHYSICAL EVIDENCE,
INTRODUCTION Plate,
BOUNDARIES Convergent,
Australia Indian,
Robert Dietz,
CONCLUSION Plate,
BOUNDARY ZONES,
Lothar Wegener,
BOUNDARIES Divergent,
MOTIONS Understanding,
continental drift,
seafloor spreading,
plate tectonics,
graph below,
plate boundary,
theory continental drift,
theory continental,
magnetic field,
theory seafloor spreading,
theory seafloor,
plate boundary zone,
crusts graph,
boundary zone,
online posting 20,
posting 20 2002,
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