theory of plate tectonics plate tectonics plate boundaries causes of plate tectonics
Post on 13-Dec-2015
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Slide 2 Theory of Plate Tectonics Plate Tectonics Plate Boundaries Causes of Plate Tectonics Slide 3 Plate Tectonics Slide 4 Questions... What is the theory of plate tectonics? What is the lithosphere? What is the asthenosphere? What are the two types of plates? Slide 5 What is the Theory of Plate Tectonics? The Earths crust and upper mantle are broken into sections called plates Plates move around on top of the mantle like rafts Slide 6 Slide 7 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 on molten rock. Slide 8 What is the Asthenoshere? The plastic like layer below the lithosphere = asthenosphere The plates of the lithosphere float on the asthenosphere Slide 9 Slide 10 2 Types of Plates Ocean plates - plates below the oceans (Basalt) Continental plates - plates below the continents (Granite) Slide 11 Plate Boundaries Slide 12 Questions... What are the three types of boundaries? What direction do plates go for each? Which boundary has a subduction zonewhat occurs at a subduction zone? Slide 13 (1) Divergent Boundaries Boundary between two plates that are moving apart RIFTING causes SEAFLOOR SPREADING - Samples collected by the Glomar Challenger showed that the youngest rocks on the ocean floor are found in the center of mid ocean ridges. Slide 14 Features of Divergent Boundaries Mid-ocean ridges rift valleys fissure (narrow opening) volcanoes Slide 15 Slide 16 Slide 17 Slide 18 (2) Convergent Boundaries Boundaries between two plates that are colliding There are 3 types Slide 19 Type 1 Ocean plate collides with a less dense continental plate Subduction Zone: where the more dense plate slides under the less dense plate VOLCANOES occur at subduction zones Slide 20 Slide 21 Andes Mountains, South America Slide 22 Type 2 Ocean plate collides with another ocean plate The more dense plate slides under the more less dense plate creating a subduction zone called a TRENCH Slide 23 Aleutian Islands, Alaska Slide 24 Type 3 A continental plate collides with another continental plate Have Collision Zones: a place where folded and thrust faulted MOUNTAINS form. Slide 25 Slide 26 Slide 27 (3) Transform Fault Boundaries Boundary between two plates that are sliding past each other EARTHQUAKES along faults Earthquakes produce seismic waves that travel through Earth. Slide 28 Slide 29 San Andreas Fault, CA Slide 30 Causes of Plate Tectonics Slide 31 Questions... What causes plates to move? How is a convection current formed? Slide 32 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. Slide 33 Slide 34 Continental Drift The hypothesis of Continental drift was that all the continents once were joined as a single super continent and have since drifted apart. To support his hypothesis, Alfred Wegener provided evidence from fossils to support the theory of continental drift.