Geology Chapter 7 – Flashcards
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Which two minerals are most common in detrital sedimentary rocks?
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clay minerals and quartz
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What is the most abundant chemical sedimentary rock in Earth's crust?
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limestone
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Working in the field, you find a rock that contains rounded fragments that are greater than 2 mm in diameter. What would you call this rock?
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conglomerate
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The geologic laboratory where you work received a sample for analysis that is composed of calcite that includes many microscopic fossils of marine organisms and reacts with acid. What name would identify this rock?
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chalk
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In the list below, indicate which of the environments fossilization is likely to occur in. Note that fossils contain organic matter.
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ocean floor
swamp
floodplain
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Rock salt is an example of a(n) __________, deposited by saturation and precipitation in evaporating water.
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evaporite
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What mineral is the major component of rock salt?
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halite
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From what you learned in the video, compare the Pleistocene climate to present-day climate of the western United States.
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The Pleistocene was wetter and cooler relative to present-day climate.
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Name the progression of coal types with increased heat and pressure from burial.
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peat, lignite, bituminous, anthracite
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Abundant plant material accumulating in a swampy environment with __________ is required for peat to form.
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low oxygen levels
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What coal is soft, black in color, and produces soot upon handling?
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bituminous
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How is anthracite produced from bituminous coal?
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metamorphism
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In the United States, the most common type of coal is __________ and the largest producing state is __________.
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sub-bituminous; Wyoming
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Which of the following defines depositional environment?
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an area where sediment was deposited under certain conditions in Earth's past
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What is a delta?
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A delta is a triangular landform created where a stream enters a body of water and deposits sediment.
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Other than sand dunes in a desert environment, where else would you expect to find well-rounded and sorted sand deposits?
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beach
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Describe the distribution of sedimentary deposits you would expect to find on a delta.
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sand in channels, mud on floodplain
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Which structure is common in sedimentary rock?
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fossils
cross bedding
mudcracks
ripple marks
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What property of detrital sedimentary rocks can be indicative of the energy of sediment transport?
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grain size
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For a detrital sedimentary rock that contains mudcracks, you could be confident that the environment in which it formed was _____.
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alternately wet and dry
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In your field area you find a quartz sandstone unit with cross-bedding in it that is on the order of 2 m high. In what environment would you deduce this rock formed?
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sand dunes
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In another field area you find a detrital sedimentary rock that contains particles larger than 264 mm that are rounded and surrounded by finer-grained particles. In what environment might you think these sediments were deposited?
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glacial moraine