Geologic Processes * Geology: the science devoted to the study of dynamic processes occurring on the earth’s surface and in its interior * Core: earth’s innermost zone. It’s extremely hot and has a solid middle surrounded by a liquid core of molten or semisolid lava * Mantle: thick zone surrounding the core. Mostly solid rock but under the outermost part lies the asthenosphere (hot, partly melted pile-able rock that flows and can be deformed like soft plastic) * Crust: outermost and thinnest zone of the earth. Consists of continental crust which underlines the continents and the oceanic crust which underlies the ocean basins and covers 71% of earth’s surface
Moving Tectonic Plates * Convection cells or currents move large volumes of rock and heat in loops within the mantle like giant conveyor belts * Flows of energy and heated material in the mantle’s convection cells cause tectonic plates to move extremely slow along earth’s surface * They float on an underlying sea of magna * Plates are composed of the continental and oceanic crust the lithosphere * Typical speed of the plate’s movement is the rate at which fingernails grow * Convergent Plate Boundary: occurs when internal forces push two plates together. Oceanic plates collide with continental plates, making the continental plate ride up over the denser oceanic plate and pushes it down into the mantle (subduction) * Subduction zone: the area where the collision and subduction takes place * Mountains are formed by two continental plates colliding and pushing up. Ex- Himalayas being formed by China and India * Divergent Plate Boundary: Oceanic plates moving apart from one another. Molten rock flows up the resulting