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87 Cards in this Set
- Front
- Back
What is a large, irregularly shaped body of crystallized magma in the subsurface?
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A Pluton
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What is a nearly horizontal layer of igneous rock called?
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A Sill
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What is cross bedding an indication of?
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Deposition from a moving fluid
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T/F: Earth's magnetic field is static, the product of magnetic minerals in the crust, mantle and core.
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False
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T/F: Earth's magnetic field resembles that of a giant bar magnet but changes with time.
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True
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Going from largest clast size to smallest, what is the correct ordering of clay, gravel, sand, and silt?
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Gravel, sand, silt, clay
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T/F: Magma and lava are completely synonymous.
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False
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T/F: Magmas contain nothing but molten rock.
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False
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Compared to immature sediment, mature sediment is what?
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More rounded
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What is melting in subduction zones largely a result of?
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Water
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T/F: Melting of rock is a common occurrence in the mantle.
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False
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T/F: Metamorphism involves melting.
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False
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T/F: Metamorphism usually changes rock composition.
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False
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T/F: Most magmas and lavas are silicic (i.e., crystallize into rocks with abundant silicate minerals).
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True
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What is ocean crust's chemical closest to?
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Gabbro
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T/F: Pyroclastic material comprises sills and dikes.
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False
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Relative to sediment near the top of an accumulation, sediment near the base was deposited when?
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Earlier
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T/F: Ripples are static features formed by interaction of wind and/or water and the rocky surface.
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False
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Do ripples propagate upstream or downstream?
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Downstream
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T/F: Seafloor magnetic lineations are visible in ocean bathymetry.
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False
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T/F: Melting of rock is a common occurrence in the mantle.
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False
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T/F: Metamorphism involves melting.
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False
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T/F: Metamorphism usually changes rock composition.
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False
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T/F: Most magmas and lavas are silicic (i.e., crystallize into rocks with abundant silicate minerals).
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True
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What is ocean crust's chemical closest to?
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Gabbro
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T/F: Pyroclastic material comprises sills and dikes.
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False
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Relative to sediment near the top of an accumulation, sediment near the base was deposited when?
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Earlier
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T/F: Ripples are static features formed by interaction of wind and/or water and the rocky surface.
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False
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Do ripples propagate upstream or downstream?
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Downstream
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T/F: Seafloor magnetic lineations are visible in ocean bathymetry.
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False
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T/F: Sediments accumulate deep in the crust.
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False
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T/F: Sediments become sedimentary rock with time--nothing else is needed.
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False
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T/F: Sediments deposited in the same layer at the same time but in different places must be practically identical.
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False
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T/F: Shield and strato volcanoes represent two different ends of the volcano morphology spectrum.
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True
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T/F: Silicate minerals are common in igneous rocks.
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True
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T/F: The composition of melt and the parent solid are identical.
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False
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What is geotherm?
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The rate at which the earth's temperature increases with depth.
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What is the horizontal banding obvious in many sedimentary rocks called?
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Bedding
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Approximately how many years ago was the last time Earth's magnetic field completely reversed polarity?
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1 Million
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T/F: The temperature of most lavas is less than 500 degree celcius.
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False
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T/F: There is lots of metamorphic rock exposed in MN.
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True
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T/F: Volcanic ash is little different from chimney ash.
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False
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T/F: Volcanic bombs are large sized tephra.
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True
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T/F: Volcanic island chains in the Pacific are arrayed in lines. This is because they represent magma leaking out through long cracks in the crust.
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False
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T/F: What rock you start with is all that matters in categorizing metamorphic rocks.
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False
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What characteristics do you need to take into consideration when classifying sedimentary rocks?
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Texture, composition, grain size, and sediment type.
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What gasses are commonly emitted by volcanoes?
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Sulfur dioxide, carbon dioxide, and water vapor.
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What type of magma is likely to be explosive?
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One that would crystallize into a rhyolite.
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What are the types of metamorphism?
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Regional, hydrothermal, contact, and burial.
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What is the most common type of metamorphism on land?
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Regional
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What physical characteristic is not important in naming igneous rocks?
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Color
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What are the three settings associated with deep sediment accumulations?
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Fore-arc basin, rifted continental margin, and accretionary prism.
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You find a rock that is light in color, has large crystals, is mostly quartz and potassium feldspar and outcrops in St. Cloud MN. What is it most likely to be?
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Granite
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What is igneous rock?
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Rock that forms when magma or lava cools and becomes solid
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What is the difference between magma and lava?
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Lava is exposed at the earth's surface and magma is beneath the earth's surface.
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What is a phaneritic igneous rock?
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A rock which is intrusive (cooled slowly underground), and the crystals can be seen with the naked eye.
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What is an aphanitic igneous rock?
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A rock which is extrusive (cooled quickly in air or underwater), and the crystals are too small to see.
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What is a porphyritic igneous rock?
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A rock which had a two (or more) stage cooling history. and contains large crystals in a fine-grained matrix.
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What is a pegmatitic igneous rock?
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A rare, intrusive (cooled slowly underground) rock with crystals larger than 2cm on average.
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What is a partial melt?
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Since rocks don't melt at one temperature, some rocks are molten but most are solid.
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What role does pressure play in melting?
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It increases the melting point of a rock.
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What role does water play in melting?
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It lowers the melting point of a rock.
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Is melt more or less dense than solid rock?
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Less dense.
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Where is melt made?
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Mid-ocean ridges, subduction zones, and hot spots.
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What are the two most common melt rocks?
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Basalt and gabbro
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What are the two kinds of volcanoes?
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Shield and strato.
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What are the characteristics of shield volcanoes?
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Low slope, usually basaltic, and non-explosive.
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What are the characteristics of strato volcanoes?
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Steep sided and explosive.
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What is tephra?
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Unconsolidated accumulations of pyroclastic grains (pieces of rock blown from volcano during eruption)
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What is tuff?
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Pyroclastic material that is welded together into rock.
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What are the three types of sediments?
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Clastic, chemical, and biogenic.
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What is a clastic sediment?
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Broken pieces from clay to boulder size.
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What is a chemical sediment?
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Preciptated from water
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What is a biogenic sediment?
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Created from shells and casts of organisms
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What are two settings that frequently result in large accumulations of sediments?
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Subduction zones and continental rift zones.
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What is graded bedding?
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Bedding with course sediment on bottom grading up to fine- usually from water.
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What is cross bedding?
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Bedding plants that are not parallel to stratification- usually results from water or air.
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What is lithification?
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The process by which sediments become a solid rock
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How does lithification occur?
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Compaction, reduction in porosity, and cementation.
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What is metamorphism?
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The process of changing in the characteristics of a rock by changes in pressure and temperature.
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What are the two types of pressure and what do they mean?
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Confining pressure (uniform, from all directions), and stress pressure (directional pressure)
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What are the characteristics of regional metamorphism?
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Most common, occurs in the cores of mountains
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What are the characteristics of contact metamorphism?
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Result of increase of temperature, grade decreases away from intrusion
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What are the characteristics of burial metamorphism?
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A thick, sedimentary blanket, low grade, rocsk retain primary structures
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What are the characteristics of cataclastic metamorphism?
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High stresses/faulting, mechanical crushing and shearing, fluid interactions
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What are the characteristics of hydrothermal metamorphism?
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Moving hot water, common near mid-ocean ridges
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What are the four most common protoliths (source rocks) or metamorphic rocks?
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Shales/mudstones, basalts, quartz-rich sandstones, and limestones
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