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Inside the Earth Layers of the Earth • CRUST • MANTLE • OUTER CORE • INNER CORE Layers of the Earth(p90) • CRUST (Lithosphere) – outermost layer – thinnest layer (5-70km thick) – consists of loose rocks & soil – 1% of Earth’s mass 2 Types of Crust • Continental= dry land • Oceanic= ocean floor Layers of the Earth • MANTLE (Asthenosphere) -layer on which pieces of lithosphere move (solid rock that moves) -thickest layer (2900km thick) -66% of earth’s mass Layers of the Earth • CORE – 2 parts of the core • 1) Outer Core=liquid iron and nickel spinning • 2) Inner Core=solid layer of iron and nickel -33% of Earth’s mass How do we know? • Seismic waves produced by earthquakes travel at different speeds through solid rock and liquids Continental Drift (p95) • Theory that continents can drift apart from one another and have done so in the past • Pangaea= single landmass ALFRED WEGENER THEORY OF CONTINENTAL DRIFT •Found evidence for PANGAEA and proposed the theory of continental drift. • Continents “fit together” like puzzle pieces WEGENER’S EVIDENCE •Fossil Evidence •fossils are remains of living things that lived long ago. •similar fossils have been discovered in matching coastlines on different continents. WEGENER’S EVIDENCE • Mountains – Some mountain ranges on different continents seem to match. • Ex: ranges in Canada match Norway and Sweden • Ex: Appalachian Mtn. match UK mtn WEGENER’S EVIDENCE • Climatic evidence such as glacial deposits in areas that are now close to the Equator Theory of Plate Tectonics • Theory that pieces of lithosphere move around on top of the asthenosphere How do the plates move? • CONVECTION CURRENTS • Hot material from deep within the Earth rises while cooler material near the surface sinks Convection currents How do we know? • Sea-floor spreading =new ocean floor is created as two lithospheric plates pull away from one another. Seafloor spreading So the plates move. Now What? •As the plates move, they produce changes in Earth’s surface, including volcanoes, earthquakes, mountain ranges, and deepocean trenches. Plate Boundaries • The edges of different pieces of The lithosphere meet at lines called plate boundaries 3 Types of Plate Boundaries Divergent Convergent Transform 3 Types of Boundaries Divergent boundary= two plates move apart • Magma rises and creates new crust or seafloor Ex: sea-floor spreading or a rift Boundary animation Divergent Boundaries © All Rights Reserved. Diverging Africa edge of the Eurasian continent/plate where it drops into a rift valley which lies between the former and the North American tectonic plate. 3 Types of Boundaries • Convergent= when two tectonic plates push into one another. Convergent Boundaries • Continental vs. Continental • Continental vs. Oceanic • Oceanic vs. Oceanic Continental vs. Continental •When two continental crustal plates collide, the continents buckle upward and form mountains. Himalayas- Asia Himalayas- Asia Continental vs. Oceanic •The oceanic plate slides under the continental plate. •The continental crust crumbles and forms new mountains or volcanoes. Subduction Zone Oceanic vs. Continental • Ex: Andes mtn in S. America Cascade Mtns. in N. America- Mt. St. Helens Oceanic vs. Oceanic •Two oceanic plates collide, one of the oceanic plates slides under the other. •also called a subduction zone Oceanic vs. Oceanic Hawaiian Islands Transform boundary • When two tectonic plates slide past each other horizontally Produces? Earthquakes San Andreas Fault New Madrid Fault The Plates Move… So what now? Which way? • 50 million years