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Plate Tectonics EQ: How do lithospheric plates move and how do they affect the Earth’s surface? An Idea Before its Time In 1912, _____Alfred Wegener______ proposed the idea of _____Continental Drift________ He suggested that all of the _________continents___________ were once ___joined_________ together to form a _______supercontinent____ Pangaea Wegener called this super landmass _______Pangaea__________ and believed that it broke apart ___200 million____ years ago Pangaea means “_______all land____” At first, his theory was ________accepted__________________________ ___Unable____ to explain how the continents drifted apart Evidence down the Road Years later came important observations that supported Continental Drift 1. ______Fossil Clues____- similar fossils found in South America and Africa and others found in Africa, Australia, India, South America, and Antarctica. 2. Rock evidence- similar rock structures are found on different continents, such as this _____mountain belt_________ that end at one coastline, only to ______reappear______ on a landmass across the _____ocean______. 3. Climate Clues- ______glacier deposits_______ and rock surfaces shows that parts of South America, Africa, India, and Australia were once covered with _________glaciers_____________ Quick Check: 1. What is Continental Drift? _____The idea that all of the continents were once joined together_______ _______________________________________________________________________________________________________________ 2. What 3 pieces of evidence support the idea of Pangaea? _Fossils, Rock Clues (mountains), Glaciers_ _______________________________________________________________________________________________________________ A New Theory Emerges Wegener could not provide an __explanation__ of exactly what made the continents move. New _____technology______ lead to findings which then lead to a ____new theory__ called __plate tectonics__ This New Evidence… With new technologies, scientists discovered a _______mountain chain_____ on the ____ocean floor___ known as the ___Mid-Ocean Ridge_______ Mid-ocean ridges are underwater chains that run through Earth’s ocean basin Seafloor Spreading Mid-ocean ridges are places where the _____________sea floor spreads___________________ As tectonic plates__________ rises to fill in the gaps The hot magma contacts ocean water, cools and hardens becoming new____rock_____ This process is known as _________Seafloor Spreading_______ Plate Tectonics The Theory of Plate Tectonics was developed in 1960s and combines _Continental Drift________ and ______Seafloor Spreading________. the theories of Scientist believe the Earth’s __crust___ and part of the __upper mantle___ is broken into 13 sections that make up the plates which move on top of the ___asthenosphere____ Convection Currents Convection currents, originating drives plate tectonic deep within the mantle provides the ______energy___ that These currents rotate in ______curricular patterns____, ______carrying heat upward__________ Plate Boundaries _____Divergent boundaries_______ are the place where two plates move __apart_. ___Convergent boundaries____ form where two plates move _together__. ____Transform____ fault boundaries are where two plates _slide___ past each other without the production or destruction of the lithosphere. Plate Tectonic Discussion Questions: 1. Explain why Wegener’s theory of Continental Drift was not accepted at first. 2. Explain what is Plate Tectonics and what causes the movement of plate tectonics. 3. What are the 3 plate boundaries and describe them.