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88 Cards in this Set
- Front
- Back
T/F: A fault is simply a crack in a rock?
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False
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T/F: A fault that cuts both a fold and an igneous intrusion proves the intrusion is older than the fold?
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False
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About how large was the largest recorded earthquake?
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9.5
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About how many years old did Bishop Ussher believe the Earth to be?
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6,000
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T/F: Aerobic bacteria appear in the geologic record more than 1 billion years ago?
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True
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T/F: An eroded syncline has the oldest rocks outcropping near the fold axis?
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False
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T/F: Carbon 14 would be a good method to assign ages to fossil organisms from the Cambrian?
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False
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T/F: Dip is measured in degrees east of north?
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False
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T/F: Ductile deformation is common in the deep crust and mantle?
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True
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T/F: Faults are expressions of brittle deformation?
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True
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From longest to shortest, order the divisions of geologic time:
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eon, era, period, epoch
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T/F: Hominids and dinosauria overlapped in time?
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False
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T/F: You drill horizontally far enough through a hanging wall in both directions, you will reach the footwall (along one of the two directions)?
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True
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T/F: In a normal fault, the hanging wall moves up relative to the foot wall?
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False
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In which rock types would you be most likely to find a fossil?
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Sedimentary
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In which tectonic setting would you most expect normal faulting?
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Divergent Boundary
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T/F: Insects predate mammals?
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True
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T/F: Justin is likely to ask questions about reverse and strike-slip faults, not just normal faults?
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True
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Lord Kelvin thought the Earth was relatively young based on?
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Heat Flow
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T/F: Meteorites were used to estimate the age of the Earth using cross-cutting relationships?
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False
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T/F: Motion of fault blocks is parallel to the fault?
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True
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T/F: Mountains are anticlines and valleys are synclines?
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False
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Normal faults are the product of which type of stress?
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Tension
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Normal faults result in horizontal?
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Extension
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T/F: Organisms with hard parts became common in the Archean
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False
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T/F: Oxygen in the atmosphere has been pretty much constant throughout Earth's history?
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False
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T/F: Prokaryotes appeared before eukaryotes?
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True
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Rocks above the brittle-ductile transition are more likely to behave?
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in a brittle fashion
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T/F: Slickensides are evidence of fault motion?
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True
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The amplitude of ground motion of a magnitude 6 earthquake is how large compared to a magnitude 5?
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ten times larger
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T/F: The Cambrian explosion refers to a massive meteorite impact?
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False
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T/F: The diversity and number of species and genera on Earth has been continuously and steadily increasing through the last 500 Ma?
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False
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T/F: The largest mass extinction that we know of was the KT boundary?
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False
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The limbs dip away from the axis of which kind of fold?
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Anticline
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T/F: The radiometric age (age estimated by dating using radioactive isotopes) of a rock isn't affected by metamorphism?
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False
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T/F: The Richter scale is a measure of earthquake damage?
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False
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Two isotopes of the same element differ in the number of?
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Neutrons
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What are stromatolites?
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Layered structures formed in shallow waters that often contain fossils.
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What is an unconformity?
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evidence of missing time in the rock record
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What is the approximate depth of the brittle-ductile transition?
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10 km
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What is the final daughter product of Uranium decay?
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Lead
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What is the half-life of a radioactive isotope?
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the time it takes for half of the original amount to decay
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When did fish first appear in the fossil record?
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Ordovician
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What are the types of stress?
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Tension, shear, compression
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What settings are likely to be a good key bed?
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An ash deposit or a layers of tektites.
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Which of the following is unlikely to be a good key bed?
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a thin layer of extrusive igneous rock
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What makes ductile deformation LESS likely?
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Increasing strain rate
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Which type of unconformity is the erosional surface between parallel sets of sedimentary strata?
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Disconformity
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What is stress?
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Force per unit area
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What happens in ductile deformation?
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It deforms without breaks, like putty.
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What happens with brittle deformation?
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It breaks into pieces, like glass.
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How does strength react in brittle and ductile deformation?
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Brittle: Strength increases with confining pressure. Ductile: Strength decreases with temperature.
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What is a strike?
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Compass bearing of any horizontal line in the plane
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What is a dip?
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The angle between the horizon and the steepest slope on a plane.
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What is a fault?
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A fracture in rock along which sliding has occurred.
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What is the block above the fault plain?
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Hanging wall.
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What is the block below the fault plan?
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Foot wall.
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What happens in a normal fault?
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The handing wall drops relative to footwall.
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What happens in a reverse fault?
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Hanging wall rises relative to footwall.
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What happens in a strike-slip fault?
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Motion is horizontal and parallel to fault strike.
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What are three ways to determine fault motion?
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Offset, drag folds, slickensides
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What is stratigraphy?
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The study of geologic strata, usually sedimentary strata, and their correlation in time and space.
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What is disconformity?
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An unconformity due to an erosional surface separating adjacent strata.
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What is nonconformity?
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An unconformity due to younger sedimentary rocks overlying igneous or metamorphic rocks.
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What is angular Unconformity?
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An unconformity due to younger beds deposited atop and truncated tilted for folded strata.
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What's the mnemonic for geologic time?
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Come over some day, maybe play poker. Three jacks cover two queens.
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How old is earth?
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Roughly 4.5 billion years old
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What age did hard parts begin showing in fossil record?
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Cambrian age
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What organisms existed in teh ordovician/silurian period?
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fish, plants, insects, marine colony
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What organisms appeared in the devonian/carboniferous period?
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Amphibians, seed plants, bony fish, reptiles.
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What happened int eh end-permian period?
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Mass extinction
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What appeared in the mesozoic period?
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Dinosaurs, mammals, crinoids, ginkgos
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What is the K-T?
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Mass extinction resulting in the end of dinosaurs.
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What appears in the cenozoic period?
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Mammals and people.
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T/F: Metamorphism involves melting.
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False
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T/F: Metamorphism usually changes rock composition.
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False
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What is geotherm?
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The rate at which the earth's temperature increases with depth.
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T/F: There is lots of metamorphic rock exposed in MN.
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True
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What are the types of metamorphism?
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Regional, hydrothermal, contact, and burial.
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What is the most common type of metamorphism on land?
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Regional
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What is metamorphism?
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The process of changing in the characteristics of a rock by changes in pressure and temperature.
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What are the two types of pressure and what do they mean?
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Confining pressure (uniform, from all directions), and stress pressure (directional pressure)
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What are the characteristics of regional metamorphism?
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Most common, occurs in the cores of mountains
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What are the characteristics of contact metamorphism?
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Result of increase of temperature, grade decreases away from intrusion
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What are the characteristics of burial metamorphism?
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A thick, sedimentary blanket, low grade, rocks retain primary structures
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What are the characteristics of cataclastic metamorphism?
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High stresses/faulting, mechanical crushing and shearing, fluid interactions
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What are the characteristics of hydrothermal metamorphism?
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Moving hot water, common near mid-ocean ridges
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What are the four most common protoliths (source rocks) or metamorphic rocks?
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Shales/mudstones, basalts, quartz-rich sandstones, and limestones
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