plate tectonics

Topics: Plate tectonics, Earth, Subduction Pages: 6 (2420 words) Published: October 26, 2013
Plate Tectonics 

Ever since the beginning on time, Humans believed the ground is solid and immobile. But this is not true whatsoever. The Earth is every-changing and continually in motion. The stability of the Earth is not at all what we think it is. Thinking about the rotational axis of the Earth, and possibly of what the Earth may become at a certain point in time, has a great influence on understanding all aspects of living things, either in the past, present, or future. The study of Plate tectonics is accredited to most of the creations of Mountain Ranges, the drifting of continents, earthquakes, and volcanic activity. Plate tectonics and mountains also play a big part in the geological features of our planet or any planet for that matter.  Geophysics, which studies the physics of the Earth, has led to many important findings about the Earth and how it is made. Seismologic studies of planet Earth have revealed new information about the inside of the Earth that has helped to give new openings in understanding plate tectonics. The Earth is made of several significant layers. Each one of these layers has its own properties. The crust is the outermost layer of the Earth. The crust is made up of the oceans and continents. The crust has a fluctuating thickness, being thirty to seventy-five kilometres thick in the continents and ten to fifteen kilometres thick in the ocean basins. The crust is made up mainly of alumino-silicates (Fowler p472).  The layer underneath the crust is the mantle, which is made up mainly of ferro-magnesium silicates. The mantle is approximately two thousand, nine hundred kilometres thick, and is separated in to the upper and lower mantle. It is in the mantle where most of the centralized heat of the Earth is located. Big convective cells in the mantle disperse heat and produce the plate tectonic processes.  The core is the last layer of the Earth, which is broken down into the liquid outer core and the solid inner core. The inner core is about thirteen hundred kilometres thick and the outer core is about twenty-three hundred kilometers thick. A nickel-iron alloy mixture makes up the outer core, and the inner is almost all composed of iron.  The Earth is separated in layers based on composition and mechanical properties. The top layer is the lithosphere, which is comprised of the solid upper mantle and the crust. It is divided into plates that move due to tectonic forces. The lithosphere floats on top of a semi-liquid layer that is called the asthenosphere. The asthenosphere allows the lithosphere to move around since it is much weaker (Tarbuck p605).  Early scientist believed that one huge supercontinent existed over two hundred million years ago. The name for this supercontinent is Pangaea. Pangaea was broken in to several pieces, and each piece was a part of the lithosphere. They believed that the pieces of Pangaea formed the continents that we know of in present day geology. When Pangaea existed, the rest of the Earth was covered by an ocean called Panthalassa. Eventually, Pangaea split into two land masses, Laurasia to the north and Gondwanaland to the south. The theory of plate tectonics does in fact have an explanation for the movement of the Earth’s crust. The fact that Pangaea did exist could be quite plausible. Scientist also believes that as the Pacific Ocean is closing, a supercontinent may form in millions of years to come. In present day geology, we can consider Eurasia as a supercontinent because the Ural Mountains separate Europe from Asia and make a line of compression and change where the two continents smashed in to each other (Tarbuck p606).  In 1620, Sir Francis Bacon wrote in his book Novan Organum and noted that the coasts of the Atlantic Ocean seemed to be parallel to one another. However, the plate tectonic theory really started to begin in 1915 when Alfred Wegener proposed the theory of continental drift. Alfred Wegener believed that the continents bulldozed through crust...
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