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175 Cards in this Set
- Front
- Back
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individual element of a landscape
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landform
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Earth's ridges, valley's & other surface features
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topography
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the idea that today's processes are the same as they were in the past and will be in the future
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uniformitarianism
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the idea that some landforms are created by a single or a series of catastrophic events
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catastrophism
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landforms developed by wind
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eolian
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landforms developed by moving liquid water
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fluvial
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landforms developed by glacial ice(solid water)
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glacial
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landforms developed by the rearrangement of the Earth's crust driven by internal energy
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tectonic
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landforms developed by waves
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coastal
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state of little change, with inputs and outputs equal
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steady-state equilibrium
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state which fluctuates around an average value, but demonstrates a trend over time.
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dynamic equilibrium
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relationship between external and internal processes and forces
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geomorphic process
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processes which occur on the Earth's surface
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external
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processes which occur or originate within the Earth's crust
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internal
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examples of external processes
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weathering & erosion by fluvial, glacial, eolian, and coastal
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examples of internal processes
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volcanism, diastrophism (mountain building), plate tectonics
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characteristics of Earth's internal structure
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* arranged in concentric layers
* heavier elements towards the center * each layer distinct in chemical composition or temperature * result of cooling since formation of the earth, some 4.6 billion years before present(BYBP) |
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how do we know the composition of the earth?
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by indirect evidence of seismic waves; their speed and direction
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velocity of a cooler seismic wave
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faster (higher)
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velocity of a hotter seismic wave
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slower (lower)
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3 types of seismic waves
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P, S, and L
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P waves are?
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push or compressional waves
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S waves are?
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sheer or shake waves
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L waves are?
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surface waves (ones we feel)
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composition of the inner core
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solid & rigid
iron (Fe) & nickle (Ni) |
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composition of the outer core
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liquid (molten), more plastic
lower melting temp iron & nickle |
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what earth layer generates 90% of the magnetic field?
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outer core
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an uneven, broad transition zone between the Outer Core and the Lower Mantle
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Gutenberg discontinuity
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a physical difference or change, esp. density, between two layers
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discontinuity
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composition of the lower mantle
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solid
oxides of iron, magnesium, & silicon |
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composition of the upper mantle
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partially molten
silicate minerals |
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comprises 80% of the Earth's volume
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upper and lower mantle
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source of magma which pushes up into crust and onto the surface
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asthenosphere
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uppermost portion of mantle, plus the crust
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lithosphere
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zone of contact between the uppermost mantle and the crust
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Mohorovicic discontinuity or Moho
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closer to the surface under oceanic crust vs continental
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Moho
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density of continental vs oceanic crust
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lower continental, higher oceanic
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composition of continental crust
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sialic rocks or sial (Si & Al)
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composition of oceanic crust
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simatic rocks or sima (Si & Mg)
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examples of continental crust rocks
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granite, shale, marble
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examples of oceanic crust rocks
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basalt, lava
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the vertical difference between highest and lowest elevation
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topographic relief
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high relief example
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mountains
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low relief example
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coastal plain
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a continent's core or nucleus of crystalline rock
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craton
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cratons are located at what elevation and age
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low, very old (precambrian)
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an exposed craton
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continental shield
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highest point above sea level
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mt Everest
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lowest point below sea level
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Mariana trench
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total relief of earth
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12.5 miles
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a method of indicating the age of the earth
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geologic time scale
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the geologic time scale is based on what?
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relative positions of rock strata
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the geologic time scale is what type of scale?
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a relative time scale
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younger rocks and sediments are near the top of a formation, & older material is near the bottom
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superposition
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determined by dating methods such as radioactive isotope dating
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absolute ages
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the geologic time scale is governed by what?
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uniformitarianism
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3 components of the geologic cycle
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hydrologic, tectonic, & rock
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cyclical movement of water(H2O)
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hydrologic cycle
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cyclical movement of crustal material and magma
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tectonic cycle
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cyclical formation of the three basic types of rock
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rock cycle
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an element or combination of elements that forms an inorganic natural compound which has specific qualities such as a unique crystalline structure, hardness, etc
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mineral
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make up about 90% of all minerals
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silicates and carbonates
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out of 3000 minerals only ____ make up 90% of crust.
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10-20
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an assemblage of minerals bound together, usually 2 to 5 different minerals
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rock
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interactions/interrelationships between the 3 rock processes
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rock cycle
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igneous rock formation
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crystallization of magma
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igneous rocks that form within the crust
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intrusive
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igneous rocks that form on the surface of the crust
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extrusive
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types of intrusive igneous rock
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plutons, batholiths, laccoliths
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types of extrusive igneous rock
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lava, basalt
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fast cooling of igneous rock creates what?
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fine-grained structure
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slow cooling of igneous rock creates what?
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coarse-grained structure
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sedimentary rock formation
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weathering, erosion, transport, and deposition of existing material
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the cementation, compaction and hardening of sediments into rock
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lithification
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sedimentary rock, such as sand or soil, formed from bits and pieces of former rocks
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clastic
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sedimentary rock made from minerals dissolved in solution, such as various salts dissolved in rivers, lakes, or oceans
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non-clastic or chemical
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examples of clastic rock
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sandstone, shale, siltstone, conglomerates
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examples of non-clastic rock
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limestone, coal, evaporites (salts)
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metamorphic rock formation
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physical and/or chemical change under high pressure and/or high temperature of existing material
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rock type is usually more compact and harder
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metamorphic
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change brought about by magma touching ("cooking")the adjacent rock
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contact metamorphism
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minerals within original rock form distinct bands or striations after metamorphism
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foliated rock
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more homogeneous mixture and few or no striations in rock
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non-foliated rock
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the theory that landmasses, the continents, have been and are moving or "floating" atop the asthenosphere
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plate tectonics
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first scientist to suggest that continents were moving and to supply some evidence for it
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Alfred Wegener
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one landmass some 225 MYBP (Triassic Period)
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Pangaea
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Pangaea broke-up into?
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Laurasia & Gondwana
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Evidence of plate tectonics
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similarities of fossils, climatic records, geological record between distant continents
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the movement of crustal material by the up-welling of magma along a system of mid oceanic ridges
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sea-floor spreading
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type of crust furthest from the ridge
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oldest
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oldest sea floor is dated 200 mybp by what evidence?
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magnetic reversals
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the polarity of the rocks in the sea-floor changes as you move away from the ridge, because it cools at different times
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magnetic reversals
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kinds of tectonic processes
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upwelling of magma, plate movement, subduction of crust, folding, faulting, warping, fracturing, earthquakes, volcanic activity
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How to tell a plate boundary?
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volcanic & earthquake activity, and the linear shape of activity
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plates moving apart from each other
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divergent plates
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plates moving toward each other
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convergent plates
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plates slide past each other
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transform or lateral plates
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stresses of divergent plates
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tensional stress
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stresses of convergent plates
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compressional stress
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stresses of transform plates
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shear stress
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divergent boundaries are formed by what?
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upwelling of magma
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example of divergent boundaries
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mid-oceanic ridges, rift zones, valleys
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convergent boundaries may create what?
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subduction zones
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convergent plate boundary where oceanic crust is subducted under the continental crust and remelted in the athenosphere
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oceanic-continetal
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an oceanic-continental boundary creates what?
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trenches and mountains due to compressed continental crust
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examples of oceanic-continental boundaries
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Nazca, S. Amer. plates create Peru Trench & Andes
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convergent plate boundary where subduction of one plate results in remelting
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oceanic-oceanic
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an oceanic-oceanic boundary creates what?
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deep trenches and high volcanic activity
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examples of oceanic-oceanic boundaries
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Philippine & Pacific plates
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convergent plate boundary of areas of great compression and mountain building
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continental-continental
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a continental-continental boundary creates what?
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earthquakes
no volcanism, subduction, or remelting |
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examples of continental-continental boundaries
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Himalayas
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transform boundaries may create what?
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transform faults, earthquakes, crustal deformation
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examples of transform boundaries
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San Andreas in S. California
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suggestion that the continents are driven by huge convective cells within the asthenosphere, but this is not the current thinking for the driving mechanism
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Theory of Thermal Convection
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current theory of plate movement suggests gravity pulls down on what?
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leading, or subducting edge
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the eruption, or intrusion, of molten rock at, or near, the earth's surface
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volcanism
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a landform with a vent or fissure on the surface which is the end of a conduit originating from below the crust
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volcano
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where magma originating in the asthenosphere, collects in a chamber below the volcano before being expelled through the conduit & out the vent
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magma chamber
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the surface depression at the summit of the volcano
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crater
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75% of volcanoes are where?
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sea floor
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molten rock issued from a volcano
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lava
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basaltic lava, less viscous (liquidy)
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mafic
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lava richer in silica thus more viscous, acidic, gas trapping
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felsic
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more explosive type of lava
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felsic
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explosively expelled fragments, common with *felsic* lava
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pyroclastics or tephra
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relatively gentle, non-violent eruptions due to less gas
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effusive
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formed if effusive eruption occurs through a vent
example? |
shield volcano
Hawaii |
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formed if effusive eruption occurs through a fissure
plateau basalts or flood basalts |
plateau basalts or flood basalts
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examples of plateau basalts or flood basalts
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Columbia Plateau of the NW U.S.
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example of effusive eruptions
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mid-oceanic ridges, Iceland
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relatively violent eruptions due to less gases and magma being trapped
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explosive
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explosive erruptions occur where?
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along subduction zones
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formed through vents of explosive eruptions
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composite volcanoes or cones (stratocones)
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example of explosive eruptions
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Mt. St. Helens, Mt. Ranier, Mt. Pinatubo
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a flood of ash, mud, & water created by melting of snowcap during an eruption or volcanic event
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lahar
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cloud of hot volcanic gas & ash that races down slope incinerating everything in its' path
example? |
nuees ardentes
Mt. Pelee (Martinique) |
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violent, explosive eruptions made more severe by water entering the magma chamber, changing to steam and increasing pressure and explosive powers
examples? |
Phreatic eruptions
Kratatau (1883), Tambora (1815), Santorini (1645 BC) |
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volcanic mountain that consists primarily of tephra, with little or no lava. Usually only a few hundred feet high.
example? |
cinder cone
Sunset Crater (AZ) |
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a mound of felsic lava which may form inside the crater of a composite cone; a kind of 'cap' over the vent
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volcanic domes
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a collapsed crater or cone of an extinct volcano; May also result from a very explosive event (Santorini).
examples? |
caldera
Crater Lake (OR), Ngorongoro Crater (Tanzania) |
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an area of very high T° within the uppermost part of the Asthenosphere that reaches the crust as a 'plume' of magma
this 'plume' creates or finds a crack in the crust, creating a conduit to the surface as the plate moves over this 'plume' it creates successive volcanic cones on the surface, often shield cones |
hot spot
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landforms & features whose origin is cooling of magma below the surface
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plutonic landscapes
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a body of intrusive igneous rock
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pluton
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type of pluton that disrupts or changes the existing geologic structure, creating an opening within the existing rock strata and then filling it in
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discordant
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type of pluton where intrusive magma that didn't disrupt or destroy the existing geologic structure, but conformed to it
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concordant
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large discordant pluton which melts most of the rock around it
examples? |
batholith
Stone Mt, Black Hills |
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magma that has cut vertically across preexisting strata and then cooled
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dike
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an erosional remnant of solidified lava-filled conduit of a composite cone
examples? |
volcanic neck
devil's tower, shiprock |
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concordant pluton which has filled an old chamber and has a domelike shape, usually smaller than a batholith
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laccolith
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magma that has inserted itself between strata of prexisting rocks, forming with a horizontal orientation
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sill
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surface wave which travels along the earth's surface
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L wave
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compression or 'push' wave which moves material parallel to its direction of movement
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P wave
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shear or 'shake' wave which moves material at right angles to its direction of movement
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S wave
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place of origin of an earthquake
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focus
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directly above focus of earthquake where L waves generated
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epicenter
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fracture where displacement of rock has occurred
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fault
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amount of shaking of the ground during an earthquake; measured by a seismograph or seismometer
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magnitude
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an instrument that measures seismic waves & earth vibrations ; uses the Richter Scale
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seismograph
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the size & damage of an earthquake measured by its impact on the human landscape (structures & activities); uses the Modified Mercalli Scale
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intensity
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crack in the rock structure
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fracture
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surface of contact along which blocks on either side of a fault move
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fault plane
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exposed cliff-like face of a fault plane created without significant erosional change
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fault scarp
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a block raised between 2 parallel faults
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horst
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a block that has sunk between 2 parallel faults
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graben
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the process of mountain building that occurs when large-scale compression leads to deformation & uplift of the crust
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Orogenesis
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a state of equilibrium formed by the interplay between the lithosphere(landmasses) & the asthenosphere
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Isostasy
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compression of crustal rock into a smaller horizontal space; shortening of the crust
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compressional fault
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where one block overrides the other block along a steep fault plane
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reverse fault
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the block that moves upward relative to the adjacent block
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upthrown block
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the block that moves downward relative to the adjacent block
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downthrown block
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compressional (reverse) fault with a very low angle of the fault plane
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thrust fault
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stretching of crustal rock apart so there is more horizontal space
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tensional fault
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a moderately inclined fault plane separating a block that has remained fairly stationary from one that has been downthrown
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normal fault
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a series of nearly parallel faults
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echelon faults
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