Geology Chapter 6 – Flashcards
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Coal beds originate in______.
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freshwater coastal swamps and bogs
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_____is a form of calcium carbonate.
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Chert
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_____is not a common cementing agent for sandstone.
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Fluorite
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What is probably the single most important, original, depositional feature in sedimentary rocks?
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bedding or stratification
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Which of the following describes the correct order for relative solubility of minerals in sedimentary rocks?
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evaporite minerals are less soluble than quartz and calcite
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Which of the following is not a type of limestone?
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Arkose
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Which of the following sedimentary features can each be used to determine paleocurrent directions?
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ripple marks and cross stratification
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A cherty limestone would contain which major constituents?
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silica; calcite
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_____sandstone contains abundant feldspar, suggesting that the sand was derived by weathering and erosion of granitic bedrock.
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arkosic
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Which of the following applies to the basic constituents of halite, gypsum, and sylvite?
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transported as dissolved ions, deposited by evaporation
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Which of the following best describes bedded gypsum and halite?
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evaporites; chemical, sedimentary rocks
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Which statement concerning sedimentary rocks is not true?
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they were originally deposited at depths below the bottom of the sea
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Which one of the following is not a chemical sedimentary rock or evaporite?
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shale
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Graywacke sandstones are typically better sorted than sandstones lithified from ancient beach sands.
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True
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Peat is thought to be the original material from which coals are formed.
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True
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Which characteristic is absolutely necessary for a sedimentary rock to have potential as a possible reservoir rock for oil or gas?
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high porosity
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Detrital sedimentary rocks are classified based on the _____.
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grain sizes of the detrital particles
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What is the main difference between conglomerate and a sedimentary breccia?
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Breccia clasts are angular; conglomerate clasts are rounded.
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Which of the following sedimentary features would typically be found in shales but not in sandstones?
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mud cracks
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Detrital grains of which minerals are extremely rare in detrital sediments?
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Calcite
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_____cement produces bright-red and yellow colors in some sandstone.
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iron oxide
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Nonclastic textures are common in which of the following sedimentary rocks?
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limestones
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Many limestones are of biochemical origin.
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true
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_____is the most common type of chemical sedimentary rock.
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Limestone
