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PLATE TECTONICS By: Ms. Susan Leonard-Balchak INDIANA STANDARDS ES.2.7 Explain that the theory of plate tectonics was finally accepted by the scientific community in the 1960’s when further evidence had accumulated evidence to support it. Understand that the theory was seen to provide an explanation for a diverse array of seemingly unrelated phenomenon and there was a profound scientific explanation of how such movement could occur. WHAT IS “PLATE TECTONICS?” • The study of the “lithosphere:” the outer portion of the earth consisting of crust and mantle • Lithosphere is divided into a dozen large “plates” • Plates move and collide with one another creating mountain ranges, volcanoes, ocean trenches etc. • Continents change through time as a result • Known as “The Theory of Plate Tectonics” THEOROIST: WEGENER • Studied rock types. glaciations, climate zones, and fossils • By this, he was able to “see” how continents must have been assembled in the geological past “Pangea:” Supercontinent "Continental Drift" 1900 Continental movement Alfred Wegener Pangea Theory of Plate Tectonics Gelogical Time Scale Supercontinent 1960's Fossils/rocks One Large Land mass originally Accepted by geoscientists Support plate tectonic theory Certain areas were "weak" and would move Adhered to continental movement Assembles time line GEOLOGIC TIME SCALE • Scientific way to sort Earth into specific time periods • Based on rock/fossil assemblage • These assemblages discern eras they were present Earth Processes for Tectonic Changes on Plate Boundaries •VOLCANOES: ABOVE AND BELOW WATER FORMATION •EARTHQUAKES: ABOVE AND BELOW WATER FORMATION •FOSSIL FUELS: NEEDED FOR USE IN TODAY’S WORLD: FORMATION PLATE BOUNDARIES • Convergent • Divergent • Transform • Plate Boundary Zones VOCABULARY FIND In groups of 2-3, link to below/find definitions for boundaries http://pubs.usgs.gov/ publications/text/unde rstanding.html CONVERGENT BOUNDARIES • “Collision” of plates: (1) Ocean to Ocean and (2) Ocean to Continental • (1)Subduction occurs (one plate slips under another) and ridges/volcanoes underwater are formed • (2)Subduction occurs and mid- ocean ridges are formed DIVERGENT BOUNDARIES • Occurs where plates move apart and new crust is created from magma pushing up through the mantle. • Causes sea floor spreading • Hypothesized to further “break apart” existing continents LiST TWO BOUNDARIES • TRANSFORM: Two • PLATE BOUNDARY plates sliding past ZONES: Any zone one another that is not horizontally explained in other • Causes “fracture processes zones” • Plate deformation • Connects 2 is seen spreading centers • Found on the ocean floor ASSIGNMENT: DUE: 07/21/05 • Define: Subduction zone, sea floor spreading, fracture zones • Sketch 4 types of boundaries and what earth process results from each (I.e. volcanoes) • http://www.ucmp.be rkeley.edu/geology/t ectonics.html.
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