Geology 1010 CH 11 – Flashcards
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Which of the following scenarios best describes the deformation that will occur in different parts of the crust?
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Brittle deformation is dominant in the shallow crust; ductile deformation is dominant in the deep crust.
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Which of the following is an example of how rocks will respond to compressional stress? (Note: there may be more than one correct answer.)
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reverse faulting
folding
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Which tectonic stress will result in a lengthening of the crust?
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tension
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Which type of stress on rock is uniform in all directions?
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confining pressure
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Which type of stress produces most crustal deformation?
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differential stress
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Which feature is not considered a rock structure?
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aa
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Which type of stress would you expect to find at a transform boundary?
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Shear. Where two plates are sliding horizontally past each other at a transform boundary, you would observe shear stress being exerted on the rocks. Because there is no vertical motion of the plates, the crustal thickness is unchanged.
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Which type of stress would you expect to find at a divergent boundary?
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Tension. Where two plates are moving away from each other at a divergent boundary, you would observe tensional stress being exerted on the rocks. This would result in relatively thinner crust along the boundary.
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Which type of force causes folding?
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Compressional force
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What is an anticline?
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A fold shaped like an upside down U
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What is a syncline?
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A fold shaped like a right-side-up U
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Imagine an anticline has been eroded to a flat surface. How would the rock age change as you walked across that flat surface?
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Rocks would be youngest on the edges and oldest in the middle.
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Imagine a fold has been eroded to a flat surface. In general, how would you know whether this fold is plunging?
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Nonplunging folds look like straight lines at the surface, and plunging folds look like wavy lines.
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What is a large, step-like fold in otherwise horizontal strata called?
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monocline
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What is a fault?
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fractures along which rocks move
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What are rocks below and above a fault called?
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the footwall below and the hanging wall above
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Which type of force is responsible for normal fault formation?
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tensional force
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Which type of force is responsible for reverse fault formation?
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compressional force
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Which type of force is responsible for normal strike-slip formation?
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shear force
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Which type of fault has NO vertical motion of rocks associated with it?
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strike-slip fault
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Which type of plate boundary is most associated with Earth's major mountain chains?
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convergent plate boundaries
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Which of the following describes an accretionary wedge?
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a chaotic accumulation of sediments and scraps of ocean crust
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What term refers to a zone where two crustal fragments are "welded" together?
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suture
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What is the geologic term for folded rocks with the bend at the bottom?
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syncline
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What are stromatolites?
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mats of blue-green algae that grew in mounds up from the sea floor
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What does a turbidite sequence consist of?
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a blanket of sand overlain by a sheet of mud
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When did Pangea begin to break into smaller fragments?
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180 million years ago
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_____ is the principle that explains why materials uplift to a certain elevation.
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Isostacy
