Chapter 3: The Dynamic Geosphere and Plate Tectonics
Chapter 3: The Dynamic Geosphere and Plate Tectonics GEOL 1005
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This 3 page Class Notes was uploaded by Kerrigan Unter on Monday October 19, 2015. The Class Notes belongs to GEOL 1005 at George Washington University taught by Brown, C in Summer 2015. Since its upload, it has received 22 views. For similar materials see Environmental Geology in Geology at George Washington University.
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Date Created: 10/19/15
GEOL 1005 Chapter 3 The Dynamic Geosphere and Plate Tectonics 3 Early Thoughts about moving continents Fossil assemblages groups of fossil species found together Gondwanaland formed from the splitting apart of Pangaea 200 million years ago Alfred Wegener developed the theory of continental drift Pangaea supercontinent formed about 250 million years ago Continental drift continents move relative to one another continental displacement 32 Explaining moving continents plate tectonics In the 1950s studies of rock magnetism began to reveal the history of Earth s magnetic field Paleomagnetism remnant magnetism a part of the magnetic field of crystals are aligned with the magnetics eld of the Earth s at the time that they were formed Apparent polar wander curves changes in the location of magnetic poles Ridges underwater mountain range Trench long narrow depression in the sea oor Seafloor spreading movement of newly formed oceanic crust away from midocean ridges Magma molten rock Magnetic stripes alternating regions of strong and weak magnetic strength that occur in oceanic crust parallel to spreading centers at midoceanic ridges Magnetic reversals Earth s magnetic eld switches polarity Plates move apart at oceanic ridges and converge and oceanic trenches Faults places where rock has broken and the blocks on opposite sides of the break have moved relative to each other Transform faults faults created by spreading movements taking places at adjacent ridge segments Plate piece of lithosphere that move relative to other pieces lithospheric plate or tectonic plate Tectonic plates are in motion they move slowly at an average rate of several centimeters per year Rifts continental lithosphere breaks and splits apart along linear valleys 33 Plate boundaries where the action is Divergent plate boundaries regions where two plates more away from each other located a major midocean ridges and continental rift zones of the world where the upwelling of hot mantle material thins the lithosphere and extends the crust Normal faults inclined breaks in the lithosphere where the upper block of rock has moved down relative to the lower block Hydrothermal vents underwater hot springs Convergent plate boundaries regions where two plates move toward each other Subduction process of the lithosphere sinking into the mantle Subduction zone subsurface zone of faulting Reverse faults faults commonly associated with subduction inclined breaks in the lithosphere where the upper block of rock has moved up relative to the lower block Thrust faults continenttocontinent collisions create broad regions of rock deformation and faulting Island arcs form in oceans Volcanic arcs form on continents Transform plate boundary where plates slide along each other if they are not diverging or converging Strike direction of movement along a plate boundary Strikeslip faults displacement is parallel to the trend or strike of the fault Scarps steep banks created by surface movements the offset streams 34 Plate tectonics the big picture Tsunami seismic sea waves Plate tectonics and volcanoes Mountain ranges are created through several ways Accretion along the continents margin Continental margin part of a continent adjacent to oceanic crust Compression at convergent plate boundaries Collision of continents at convergent plate boundaries Magma 0 Plate tectonics create valuable mineral deposits along convergent plate boundaries