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Plate Tectonics Plate Tectonics Plate Tectonics Plate Boundaries Causes of Plate Tectonics What is Plate Tectonics The Earth’s crust and upper mantle are broken into sections called plates Plates move around on top of the mantle like rafts What is the Lithosphere? The crust and part of the upper mantle = lithosphere 100 km thick Less dense than the material below it so it “floats” What is the Asthenoshere? The plastic layer below the lithosphere = asthenosphere The plates of the lithosphere float on the asthenosphere Questions... What is the theory of plate tectonics? What is the asthenosphere? 2 Types of Plates Ocean plates - plates below the oceans Continental plates plates below the continents Plate Boundaries Divergent Boundaries Boundary between two plates that are moving apart or rifting RIFTING causes SEAFLOOR SPREADING Divergent boundary of two continental plates. rift valley East African Rift Creates a __________. Example: _____________ Features of Divergent Boundaries Mid-ocean ridges rift valleys fissure volcanoes subduction a TRENCH zone called Convergent Boundaries Boundaries between two plates that are colliding There are 3 types… Type 1 Ocean plate colliding with a less dense continental plate Subduction Zone: less dense plate slides under the more dense plate VOLCANOES occur at subduction zones Andes Mountains, South America Convergent boundary of an oceanic plate and a continental plate. Forms a _______ volcanic mountain range trench Examples: Cascades Andes Mts and a ______. _______ or _______ Type 2 Ocean plate colliding with another ocean plate VOLCANOES occur at subduction zones Aleutian Islands, Alaska Convergent boundary of two oceanic plates. island arc and a _____. trench Example: _____ Japan Creates an ________ Type 3 A continental plate colliding with another continental plate Have Collision Zones: mountains form. Convergent boundary of two continental plates. Forms Himalayas a ______ folded mountain range. Examples: ___________, Appalachians Alps, ______________ Transform Fault Boundaries Boundary between two plates that are sliding past each other EARTHQUAKES along faults San Andreas Fault, CA Transform-fault boundary where the North American and Pacific plates are moving ____ past each other. San Andreas Fault in California Example: ________________ Diagrams Questions... What are the three types of boundaries? What direction do plates go for each? Which boundary has a subduction zone…what occurs at a subduction zone? Plate Boundaries Review Places where plates move apart are called _____________ boundaries. divergent rift valley is When continental plates diverge a ___________ formed. When two oceanic plates converge what is an island arc and a trench created? _____________________ The Appalachians formed mainly from continental plate collisions and therefore are a __________ folded mountain range. Convection currents The force moving the plates is ________________ . Causes of Plate Tectonics What cause plates to move? Convection Currents Hot magma in the Earth moves toward the surface, cools, then sinks again. Creates convection currents beneath the plates that cause the plates to move. The less dense plate slides under the more dense plate creating a subduction zone called a TRENCH Subduction Zone: where the less dense plate slides under the more dense plate VOLCANOES occur at subduction zones Explain Pangaea This is what type of boundary ? What are the two types of plates? Divergent plate boundaries move_______ Tectonic plates move only _______ per year Kilometers B. Miles C. Centimeters D. Millimeters A. This type of plate movement can result in the formation of mountains and/or volcanoes What is the lithosphere? Two transformative plates slide past each other. What geological event is likely to occur? Questions... How is a convection current formed? What are the three types of plate boundaries? What causes plates to move?
