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Transcript
Learning Objective • Identify and describe earth’s major geological processes. • Describe earth’s major geological hazards. Agenda • Notes Homework The Earth • Core: innermost zone, solid inner part surrounded by molten rock • Mantle: layer on which the crust floats • Ch. 8 Aquatic Biomes Quiz Zero Hour – – • Asthenosphere: pliable inner layer Lithosphere: rigid outer layer + crust Crust: outer/thinnest zone made mostly of oxygen – Continental and oceanic How the crust moves… • Convection cells move rock and heat in loops in the mantle like giant conveyor belts causing rigid plates (tectonic plates) to move extremely slow over the surface. – “Float” on the asthenosphere • Much geological activity takes place at the plate boundaries Pg. 346 1 The Earth’s 15 Major Tectonic Plates 3 Major Kinds of Plate Boundaries • The extremely slow movements of these plates cause them to move apart , grind into one another, and/or slide past one another. Divergent Plate Boundaries • Oceanic plates moving apart from one another in the ocean, causing magma to flow up. – Creates oceanic ridges Transform Faults • Plates slide and grind past one another along a fracture in the lithosphere. • Most are located on ocean floor, a few on land – Friction spawns earthquakes along slipstrike faults 2 Convergent Plate Boundaries • Plates collide into one another • Oceanic-continental: continental less dense so rises above oceanic; oceanic pushed down (subduction) Convergent Plate Boundaries • Oceanic-oceanic: a trench usually forms – Also causes island arcs – Forms volcanoes Convergent Plate Boundaries • Continentalcontinental: push up mountain ranges Plate Tectonics video 3 Hot Spots • Fixed places in the mantle or oceanic lithosphere where rocks melt to generate magma. Plate Boundaries WS – In the ocean, it can create shield volcanoes that may build high enough to become volcanic islands (Hawaii) – The Yellowstone hotspot creates calderas 4