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Download plate tectonics - Ector County ISD.
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PLATE TECTONICS • TEKS 8.9B relate plate tectonics to the formation of crustal features; • TEKS 6.10C identify the major tectonic plates • TEKS 6.10D describe how plate tectonics causes major geological events such as ocean basins, earthquakes, volcanic eruptions, and mountain building What is Plate Tectonics? Plate tectonics describes the means by which the oceanic and continental crust are able to move and the results of that motion. The crust of Earth is divided into plates. Key plates: • Eurasian • African • Indo-Australian •Pacific •Nazca •North American •South American The plates are rigid and in constant motion relative to one another. What Causes the Tectonic Plates to Move? Intense heat from the core of the Earth causes convection cells to form in the asthenosphere. The Earth’s continental and oceanic plates sit on the hot asthenosphere. While the rock in the asthenosphere is solid, it is less rigid than the plates, and therefore moves. While scientists do not fully understand the forces that move the plates, it is believed that the moving material in the asthenosphere drags the plates along. What Are the Results of Tectonic Plate Motion? Each plate moves as a distinct unit. The borders between plates are called plate boundaries. There are three different kinds of motion that occurs between the tectonic plates. •Transform Plate Boundary •Divergent Plate Boundary Even though the motion of the plates is very slow; about 1040 mm/year (this is about how fast your fingernails grow), the motion causes major geologic events and surface features. I can out run the tectonic plates! TRANSFORM Motion: plates grind past one another Surface Feature: faults Geologic Event: earthquakes San Andreas Fault Click here! Surface DIVERGENT Feature: Motion: •Rifts plates •Rift move Geologic valleys away Event: from one •Volcanic another •new crust islands is formed •mid•shallow ocean earthquakes ridge rift valley Click here! Mid-Atlantic Ridge CONVERGENT Motion: plates move toward from one another Geologic Event: •crust material is destroyed •earthquakes •volcanic eruptions •mountain building CONVERGENT Surface Features: • volcanoes • Island arcs • Volcanic arcs • Trenches • Mountain ranges Mount Saint Helens Click here! The Himalayan Mountains Click here!
