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21 Cards in this Set
- Front
- Back
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What is the difference between a bed and a lamina?
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lamina is much thinner than bed
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Be able to apply the descriptions of bedding surfaces (e.g., even & parallel, discontinuous, wavy, etc…)
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slide 2
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What are the causes of bed deformation? How is lithology a control?
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bed deformation is caused by sediment transport
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What is the difference between lenticular, wavy and flaser bedding?
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.
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How does normal grading form?
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normal grading is the systematic reduction in the size of particles constituing bed from its base to its top.
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What are load features? What conditions give rise to these?
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load features are the result of an unstable difference in the density of a deposit and its immediate substrate
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What are flame structures? What conditions give rise to these?
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different densities
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When/how do fluid escape structures form? Dish structures?
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dish structures are produce by a relatively slow upward flow of pore fluid that transports finer particles through the grain framework.
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What are rip-up clasts? What lithology are these usually? Why?
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What is contorted bedding? How does it form?
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. structure associated with local permeability barriers that trap elevated pore pressures.
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What are ball & pillow structures?
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. possibly results of liquefaction
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What are the causes for a sand bed to appear structureless?
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What are sand dikes? Sand volcanoes?
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results of liquefaction. high pore pressure fracture confining layer and drive flow sand and pore water.
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What do mud cracks form in mud and not sand?
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How do flute marks form? How do they indicate flow direction?
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flute marks are formed by focuse erosion by turbulent eddies. steep side of a flute points upstream
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How do tool marks form? How do they indicate flow direction?
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Tool Marks are formed by objects carried by flow interacting with the bed, (e.g. grooves, skip marks). transport direction is parallel to long dimensions of tool mark. difficult to determine which direction is correct.
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What is the difference between tracks, trails, burrows, and grazing structures as trace fossils?
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quite obvious look at slides 20-24
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What is a trace fossil?
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Non-body remain indicating the activity of plants or animals. (footprings, trails, boring, and burrows.)
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What is bioturbation?
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disturbance by organism, digging, burrowing or simply moving across the surface.
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How is a boring different from a burrow?
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burrows are in the dirt, borings into hard substrates
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Liquefaction
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transformation of water-saturated sediments from the solid to liquid state as a response to increased pore pressure
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