•• • • Unifying theory of geology All geological features and processes are related Concepts were drawn together in 1968 Processes associated with the origin, movement, and destruction of the lithospheric plates Motion of earth’s lithosphere Lithosphere is made up of moderately rigid plates (may consist of oceanic or continental lithosphere) = 7 major plates + several smaller plates “pulling apart” – divergent “sliding” – transform “crashing” – convergent Places where plates crash into each other (oceanic – continental) . Places where plates crash into each other (continental – continental) . Places where plates crash into each other (oceanic – oceanic) . Places where plates are being pulled away from each other . Places where plates slide past each other . . . Why? What causes the plates to move? . some skeptics refuse to accept it.In spite of the overwhelming evidence to support the ideas of Plate Tectonics. cold materials sink .Convection currents Hot materials rise. a. b. Two-layer convection – separated at depth of 660 kilometers Whole-mantle convection – entire 2900-km mantle . Slab-pull . Hot spots – provide a frame of reference for tracing the direction of plate motion . long-lasting.relatively small. provide localized sources of high heat energy (thermal plumes) to sustain volcanism . and exceptionally hot regions which exist below the plates. . Global Positioning System ~7 cm/year ~9 cm/year . . Manila Trench East Luzon Trough Negros Trench Philippine Trench Sulu Trench Cotabato Trench . Babuyan Claro Taal Canlaon . . A naturally-occurring aggregate of one or more minerals. Types of rocks vary based on composition. texture. structures. may or may not contain mineraloids. etc. . natural glass and organic matter. color. Igneous rocks ◦ formed from solidification of magma ◦ extrusive if they crystallize on the surface of the earth and intrusive if beneath the surface Sedimentary rocks ◦ Formed when sediments are transported. pressure and chemically active fluids beneath the earth’s surface . deposited and then lithified by natural mechanisms Metamorphic rocks ◦ Formed from preexisting rock by the effects of heat. . metamorphic and sedimentary rocks. Group of processes that produce igneous. The rock cycle is linked to other subcycles: Tectonic cycle for heat and energy Biogeochemical cycle for materials Hydrologic cycle for water used in processes of weathering. transportation. deposition and lithification of sediments . erosion. Circulation of water from the oceans to the atmosphere and back to the oceans by way of precipitation. runoff from streams and rivers. and groundwater flow . evaporation. including atmosphere. lithosphere. Movement of a chemical element or compound through the various earth systems. biosphere and hydrosphere Cycles include: ◦ ◦ ◦ ◦ ◦ Carbon Oxygen Nitrogen Phosphorus Sulfur .
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