Understanding Plate Motions - Earthquakes 1 Understanding...

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Earthquakes 1 Understanding Earth and Plate Motions By: Selina Appel SCI/245 Scott Rought January 10, 2010
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Earthquakes 2 The plate tectonics are constantly moving all over the world, in relation to each other. Between the boundaries of plates, are zones with earthquakes and active faulting. Plate boundaries have three types convergent, divergent, and transform, and two types of crust, oceanic crust and continental crust; that can be involved in this faulting. In this essay it will show, how these tectonic plates move therefore causing the Earth to shift and move to become an Earthquake. Continental Crust What is the continental crust? The layer of sedimentary, igneous, and metamorphic rocks make up the continental crust; there are areas of a shallow seabed close to the shores known as the continental shelves. Due to more granite, or felsic, this layer or area can be sometimes called the sial. Bulk composition, which lies in contrast to the oceanic crust , called sima due to its mafic , or basaltic rock. The surface of the Earth when looked at consists of 71% water, and the land portion consists of 29%. When divided the lands become six big pieces, known as the continents. The continents that arrange in different shapes and sizes, these are Africa, South America, Australia, North America, Antarctica, and Eurasia (Asia and Europe together.) In the past, the continents division were different, the theory is that these continents were one big piece of land; and over time have shifted into many different continents due to the motion of the plates. Below the Earth, the crust of continents the thickest, the average of the thickness is about 20 to 25 miles (30 to 40 km) and with a maximum of 45 miles (70 km). The oceanic crust is much younger than the continental crust. The continental crust mainly consists of igneous rocks that are divided into two layers. Some of these rocks are 3.8 billion years old. The upper portion of the mantle or crust consists of granite rocks, were as the lower portion of the mantle or crust
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