Plate tectonics is the grand, unifying theory of Earth sciences, combining the concepts of continental drift and sea-floor spreading into one holistic theory that explains many of the major structural features of the Earth's surface. It explains why the oceanic lithosphere is never older than about 180 Ma and why only the continents have preserved the Earth's geological record for the past 4000 Ma. It provides the framework to explain the distribution of earthquakes and volcanoes and a mechanism for the slow drift of the continents across the Earth's surface. The theory has now reached such a level of scientific acceptance that the movement of plates, both relative to one another and to the hot-spot reference frame, are being used to infer movement of the hot-spot reference frame with respect to the Earth's rotational axis.
Plate tectonics is an expression of the convective regime in the underlying mantle, but the link between individual convection cells and plate boundaries is not direct because plate boundaries are not fixed and, like the plates, move relative to one another. Plate movements are driven by gravity, largely by cold, dense lithospheric slabs pulling younger lithosphere towards a destructive boundary. A less-powerful driving force is generated by the potential energy of spreading centres, elevated some 2-3 km above the general level of the abyssal plains.
As ideas concerning plate tectonics have evolved since the 1970s, it has become apparent that while the theory can be applied rigorously to the oceans, the same cannot be said of the continents. Because of the strength and rigidity of oceanic plates, deformation is focused into narrow linear zones along plate margins. By contrast, when continental lithosphere approaches a plate boundary, deformation can extend hundreds of kilometres into the continental interior because continental plates are less strong. Such deformation gives rise to the major mountain belts of the Earth, as exemplified by the Alpine Himalayan Chain.
Plate Tectonics Essay
1.0 Topic Definition
Plate Tectonics is a scientific theory which study how the Earth’s plates are driven and shaped by geological forces to keep them in constant movement. The theory explains the present-day tectonic behavior of the Earth, particularly the global distribution of mountain building, earthquake activity, and volcanism in a series of linear belt. (Pitman, W.C., 2007)
Plate Tectonics explains geomagnetic and geothermal phenomena, magma and orogenesis, and it clarify the global mid-ocean ridges and rift system, etc. The theory also analyzes geological issues such as the origin of oceanic crust. Plate Tectonics has a significant effect on all fields of geology because it helps explain many geological phenomenons.
Figure1. Earth Plate
Way back to 1915, scientist Alfred Wegener proposed his theory of “Continental Drift”, which clarified that the continents plowed through crust of ocean basin s. It helped explain why the outlines of many coast lines, such as South America and Africa looked like a puzzle when they fitted together. However, Wegner’s theory was controversial because it lacked of explanation of why continents moved.
In 1929, Arthur Holmes elaborated on one of Wegner’s hypotheses: the mangle undergoes thermal convection. In the early of 1960s, Holmes’ idea received many attractions. Harry Hess and R. Deitz developed a similar hypothesis, known as “Sea floor spreading”.
In 1965, J.T. Wilson proposed a new theory, which was “Plate Tectonics”. In 1967, Xavier Le Pichon published a complete model based on 6 major plates with their relative motions, which refined the theory of “Plate Tectonics”. He also explained the principle of the movement of the plates.
3.0 Science Organization
Plate Tectonics belongs to Geology. Plate Tectonics covers geophysics, tectonics, marine geology, geomorphology, volcanology and seismology. Geology is a subject which studies the Earth, the materials of it, the structure of those materials and the movement of them. Plate Tectonics studies the movement, evolution, composition, portfolio construction, distribution and mutual relations of the Earth’s lithosphere plates, which is similar to subject of geology.
In junior high school, I have learned the Continental Drift Theory, and my geography teacher told me there was a new theory based on the Continental Theory, i.e. Plate Tectonics. I accessed to the Internet to find the information about Plate Tectonics.
There are three distinct types of plate boundaries existing, which are supported by geological observation, geophysical data, and theoretical considerations. Their names and categories are based on if adjacent plates move apart from each other (divergent plate margins), toward one another (convergent plate margins), or slip past one another in a direction parallel to their common boundary (transform plate margins) (Pitman, W.C., 2007).
The new volcanic material welling up into the...
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