Questions and Answers
Chemical and biochemical rocks are classified primarily on the basis of ____________.
mineral composition
Beach sediments would travel ___________ the ocean during a transgression and ___________ the ocean during a regression.
away from; toward
The difference between breccia and conglomerate is that conglomerate ____________.
possesses more rounded grains than breccia
Physically precipitated (chemical) limestone that forms in caves is termed ____________.
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Geologists call individual layers of sedimentary rocks _____________ , whereas several of them together are called ____________.
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Two major sources of energy, coal and oil shale, are considered ____________ sedimentary rocks.
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Waves cause beach sand to be ____________.
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Swamps, channels, floodplains, and submarine slopes all play a role in the development of ____________.
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Ripples, dunes, and cross bedding are sedimentary structures that can be used to determine _____________.
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Clastic sedimentary rocks are primarily classified on the basis of ____________.
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Which transport medium carries the largest particles?
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Unlike physically precipitated chert, biochemical chert ____________.
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If a geologist found preserved mud cracks, he or she could conclude that the environment in which they formed ____________.
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Stratification refers to ____________.
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Which environment would most likely produce sedimentary deposits characterized by poorly to moderately sorted, angular to subangular grains that consist of feldspar, quartz, and lithics (rock fragments)?
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Distinct internal laminations that are inclined at an angle to the boundary of the main sedimentary layer are called ___________.
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What type of sediment is found in lake bottoms?
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Grains become rounded primarily during ____________.
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Chemical weathering takes place most rapidly in environments that are ____________ and ____________.
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Cemented shells of marine organisms form which kind of sedimentary rock?
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Because the velocity of sediment settling (deposition) is positively related to grain size for waterborne sediments, fluvial deposits are more likely than glacial deposits to ____________.
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A clastic rock comprised of sand-sized grains derived from the physical weathering of granite and containing a sizable proportion of feldspar is termed ____________.
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Death Valley, part of the Basin and Range Province, has been sinking due to the weight of continuously accumulating sediment shed from the Black and Panamit Mountains that border the valley. What phenomenon is this an example of and what depositional environment is created by the sediment deposition?
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Compaction and cementation of grains occurs during ____________.
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A well-sorted sandstone with asymmetric ripples was most likely deposited as sand by a ____________.
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Sedimentary deposition is a continuous process: rivers, lakes, and the ocean deposit sediments nonstop at a fairly constant rate.
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As compared with metamorphism, diagenesis ____________.
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Physical precipitation of gypsum due to evaporation of seawater produces which kind of sedimentary rock?
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A fine-grained clastic rock that splits into thin sheets is ____________.
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What causes the formation of an alluvial fan?
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The breakdown of exposed rock into small fragments and dissolved ions is termed ____________.
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The majority of the rocks that occur at the surface of Earth are ____________.
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Sea level rises locally, and marine sediments are deposited on top of terrestrial sediments during events termed ____________.
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If water is the transport mechanism of sediment, the grain size of sedimentary deposits most closely indicates the ____________.
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Diagenesis refers to ____________.
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Asymmetric ripples are indicative of unidirectional flow, whereas symmetric ripples are indicative of flow in multiple directions.
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The removal of detritus from weathered rock at an outcrop is termed ____________.
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What effect would plants have on a sand dune environment?
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Glacial till is composed of ____________ sized particles.
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Biochemical limestones are dominated by carbonate mud and fragments of ____________.
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Pulling a block of clay apart, resulting in the middle portion thinning and sinking, is an adequate analogy for ___________.
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Limestone is most likely formed in which of the following environments?
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Which environment would most likely produce sedimentary deposits characterized by very well-sorted, very well-rounded grains that are nearly pure quartz?
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As compared to arkose, quartz sandstone ____________.
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In which of the following phenomenon are sediment records NOT preserved?
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When limestone becomes chemically altered so that half of the calcium atoms are replaced by magnesium, the resultant rock is termed ____________.
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Siltstone or mudstone containing marine fossils likely formed in a ___________ environment.
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Similar sediment and depositional thickness can be found in all sedimentary basins.
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It is unusual for ____________ to carry grains larger than sand.
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If a geologist were to dig below the current beach and find offshore sediments underlain by beach and swamp deposits then he or she could conclude that ____________ has occurred.
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Topset, foreset, and bottomset beds are indicative of ____________.
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Diagenesis requires ____________.
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Graded beds tell a geologist that a ____________.
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Study Notes
Classification of Sedimentary Rocks
- Chemical and biochemical rocks are classified based on mineral composition.
- Clastic sedimentary rocks are primarily classified by grain size.
Sedimentary Processes and Environments
- During a transgression, beach sediments move away from the ocean; during a regression, they move toward it.
- Marine deltas develop in environments like swamps and floodplains.
Sedimentary Structures and Characteristics
- Breccia has angular grains, while conglomerate features more rounded grains.
- Features like ripples and dunes can reveal wind and current directions as well as past environments.
Lithification and Rock Formation
- Lithification involves compaction and cementation of sediments transforming into rock.
- Diagenesis refers to changes in sediment, including physical and chemical alterations at lower temperatures and pressures than metamorphism.
Sediment Transportation
- Ice is capable of transporting the largest particles, compared to water and wind.
- Transportation leads to grain rounding and sorting due to environmental conditions.
Rock Types and Composition
- Clay is the primary sediment found in lake bottoms, while shale is a fine-grained clastic rock that splits into thin sheets.
- Biochemical limestones primarily consist of calcitic and aragonitic skeletons of marine invertebrates.
Deposition Dynamics
- Alluvial fans form through decreased velocity and load capacity, capturing sediment from varied sources.
- Graded beds indicate deposition a result of turbidity currents, depositing coarser material first.
Environmental Indicators
- Mud cracks indicate a previously wet environment with sediment deposition.
- Asymmetric ripples indicate unidirectional flow; symmetric ripples suggest multidirectional flow.
Sea Level Changes
- Transgressions involve marine sediments covering terrestrial sediments due to rising sea levels.
- Regression occurs when sea levels fall, exposing previously submerged areas.
Sorting and Grain Size Relationships
- Well-sorted sandstone indicates high transport energy, commonly found in river environments.
- Quartz sandstone is more mature and found farther from the weathering source compared to arkose.
Special Cases and Exceptions
- Chemical weathering occurs most rapidly in warm, wet environments.
- Wind typically cannot carry grains larger than sand, highlighting its limitations in sediment transport.
Recognizing Biochemical Processes
- Physical precipitation of minerals, like gypsum from evaporating seawater, produces chemical sedimentary rocks.
- Travertine forms from chemically precipitated limestone in caves, while dolostone results from limestone alteration.
Fossil Evidence
- Marine fossils in siltstone suggest formation in a shallow-marine environment.
General Observations
- Sediments deposited in various basins can differ greatly in thickness and composition.
- Despite seeming continuity, sediment deposition is not always uniform, varying by environmental conditions.
Studying That Suits You
Use AI to generate personalized quizzes and flashcards to suit your learning preferences.
Description
Test your knowledge on sedimentary rocks with these flashcards covering key concepts from Chapter 7. Each card is designed to help reinforce your understanding of mineral composition and sediment transport during geological transgressions and regressions.
