Tectonic Plates – Flashcards
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Abraham Ortelius
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Dutch mapmaker who noticed the fit of the continents on either side of the Atlantic Ocean in the 16th century.
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Eduard Suess
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Austrian geologist who theorized Gondwanaland.
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Alfred Wegener
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Contributed his idea of continental movement to the scientific community, it was called continental drift.
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Continental Drift
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Proposes that the Earth's continents had once been joined as a single landmass.
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Pangaea
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Greek word meaning "all the earth."
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Wegener's Proof (What he used as)
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Rocks, fossils, and climatic data.
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Fossils (Wegener's specimens)
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Kannemeyerid, Labrinthodont, Mesosaurus, Glossopteris, etc.
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Ancient Climatic Evidence (Example)
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Coal deposits in Antarctica, and glacial deposits in Africa, India, Australia, and South America.
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Magnetometer
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A device used to map the ocean floor that detects small changes in magnetic fields.
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Paleomagnetism
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Study of Earth's magnetic record using data gathered from iron-bearing minerals in rocks that have recorded the orientation of Earth's magnetic field at the time of their formation.
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Magnetic Reversal
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A change in Earth's magnetic field over geologic time, recorded in ocean-floor rocks and continental basalt flows.
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Isochron
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Line on a map that connects points of the same age.
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Seafloor Spreading
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Hess's theory that new ocean crust is formed at mid-ocean ranges and destroyed at deep-sea trenches. It occurs in a continuous cycle of magma intrusion and spreading.
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Helpful Technology (Seafloor Spreading)
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-Sonar and other echo-sounding methods -Magnetometer
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Ocean Ridges
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Vast, underwater mountain changes where earthquakes occur. Their size has triggered much discussion.
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Deep-Sea Trenches
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Narrow, elongated depressions in the seafloor with very steep sides.
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Mariana Trench
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The deepest chasm, 11km+ deep.
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Two Major Discoveries From Rock & Sediment Analyses
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1. The ages of rocks vary in different ways, and their changes are predictable. 2. The thickness of ocean-floor sediment is less that expected.
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The Geomagnetic Time Scale
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A polarity time scale.
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Normal Polarity (+)
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A magnetic field that has the same orientation as Earth's present field.
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Reversed Polarity (-)
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A magnetic field that doesn't have the same orientation as Earth's present field.
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Continental Basalt Flows
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Used to construct the geomagnetic time scale.
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Epochs
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Long term changes in Earth's magnetic fields, four of which have occurred in the past.
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Events
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Short term changes in the Earth's magnetic fields.
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Theory Of Plate Tectonics
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States that Earth's crust and upper mantle are broken into plates, which are huge rock slabs that move in different directions and at different rates over the Earth's surface.
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Divergent Boundary
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A place where two of Earth's tectonic plates are moving apart; is associated with volcanism, earthquakes, and high heat flow; found on the seafloor.
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Rift Valley
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Long, narrow depression that forms when continental crust begins to separate at a divergent boundary.
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Convergent Boundary
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A place where two of Earth's tectonic plates are moving towards each other; is associated with trenches, islands ark, and folding mountains.
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Subduction
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Process by which one tectonic plate slips beneath another tectonic plate.
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Transform Boundary
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A place where two tectonic plates slide horizontally past each other that is characterized by long faults and shallow earthquakes.
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Convergent Boundary Types/Tectonic Boundaries
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1. Oceanic-Oceanic: Oceanic crust converging with oceanic crust; a form of subduction. 2. Oceanic-Continental: Oceanic crust converging with continental plates, or vice versa. 3. Continental-Continental: Continental crust converging/colliding with continental crust.
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Ridge Push
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Tectonic process associated with convection currents in Earth's mantle that occurs when the weight of an elevated ridge pushes an oceanic plate toward a subduction zone. A cause of plate motions.
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Slab Pull
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Tectonic process associated with convection currents in Earth's mantle that occurs as the weight of subducting plate pulls the trailing lithosphere into a subduction zone. A cause of plate motions.
