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196 Cards in this Set
- Front
- Back
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A clastic sedimentary rock composed of sand-sized grains that include quartz and feldspar.
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arkose
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A distinct layer of sedimentary strata.
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bed
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Sedimentary rock formed from material (such as shells) produced by living organisms.
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biochemical sedimentary rock
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Coarse sedimentary rock consisting of angular fragments; or rock broken into angular fragments by faulting.
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breccia
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The phase of lithification in which cement, consisting of minerals that precipitate from groundwater, partially or completely fills the spaces between clasts and attaches each grain to its neighbor.
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Cementation
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Sedimentary rock made up of minerals that precipitate directly from water solution.
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chemical sedimentary rock
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Sedimentary rock consisting of cemented-together detritus derived from the weathering of preexisting rock.
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clastic sedimentary rock
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A fragment of detritus (e.g., a sand grain or a pebble).
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Clasts
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Very coarse-grained sedimentary rock consisting of rounded clasts.
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Conglomerate
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A lamination inclined to the main bedding; it represents the slip face of a layer deposited in a current.
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cross bed
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The process by which sediment settles out of a transporting medium.
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Deposition
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Changes that happen to sediment or sedimentary rock during and subsequent to lithification but at temperatures less than that of the lowest grade metamorphism.
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diagenesis
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A type of carbonate sedimentary rock that contains significant quantities of dolomite.
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dolostone
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The grinding away and removal of Earth's surface materials by moving water, air, or ice.
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erosion
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A layer of clastic sediment or sedimentary rock in which clast size progressively decreases from the base to the top of the bed; graded beds form by deposition from a turbidity current.
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graded bed
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Sedimentary rock composed of calcite.
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Limestone
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The transformation of loose sediment into solid rock through compaction and cementation.
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lithification
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Very fine-grained sedimentary rock that will not easily split into sheets.
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mudstone
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Sedimentary rock (such as coal) formed from carbon-rich relicts of organisms.
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organic sedimentary rock
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The seaward migration of a shoreline caused by a lowering of sea level.
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regression
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Wave-like ridges and troughs on the surface of a sedimentary layer formed during deposition in a current.
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ripple marks
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Coarse-grained sedimentary rock consisting almost entirely of quartz.
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Sandstone
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A depression, created as a consequence of subsidence, that fills with sediment.
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sedimentary basin
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Rock that forms either by the cementing together of fragments broken off preexisting rock or by the precipitation of mineral crystals out of water solutions at or near the EarthÕs surface.
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sedimentary rock
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A characteristic of sedimentary deposits that pertains to the character of bedding and/or the surface features of a bed.
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sedimentary structure
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Very fine-grained sedimentary rock that breaks into thin sheets.
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shale
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Fine-grained sedimentary rock generally composed of very small quartz grains.
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siltstone
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(1) The range of clast sizes in a collection of sediment; (2) the degree to which sediment has been separated by flowing currents into different-size fractions.
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Sorting
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A succession of sedimentary beds.
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strata
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A recognizable layer of a specific sedimentary rock type or set of rock types, deposited during a certain time interval, that can be traced over a broad region.
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stratigraphic formation
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The vertical sinking of the EarthÕs surface in a region, relative to a reference plane.
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Subsidence
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The inland migration of shoreline resulting from a rise in sea level.
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transgression
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A carbonate rock formed by precipitation of carbonate minerals from water at springs or on the surface of caves.
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travertine
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A submarine avalanche of sediment and water that speeds down a submarine slope.
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turbidity current
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Metamorphism due to the increase in temperature and pressure in a rock when it has been buried to a depth of several kilometers.
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burial metamorphism
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Metamorphism caused by heat conducted into country rock from an igneous intrusion.
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contact metamorphism
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A condition causing a material to experience a push or pull in one direction of a greater magnitude than the push or pull in another direction; in some cases, differential stress can result in shearing.
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differential stress
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Metamorphism that occurs as a consequence of shearing alone, with no change in temperature or pressure.
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dynamic metamorphism
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Metamorphism that involves heat, pressure, and shearing.
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Dynamothermal metamorphism
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The process (involving uplift and erosion) that returns deeply buried rocks to the surface.
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Exhumation
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Layering formed as a consequence of the alignment of mineral grains, or of compositional banding in a metamorphic rock.
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foliation
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A compositionally banded metamorphic rock typically composed of alternating dark- and light-colored layers.
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Gneiss
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Rock that undergoes metamorphism simply because of a change in temperature, without being subjected to differential stress.
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Hornfels
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The change that occurs in a rock due to interaction with high-temperature water solutions.
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hydrothermal metamorphism
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A metamorphic rock composed of calcite and transformed from a protolith of limestone.
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Marble
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Conglomerate that has undergone metamorphism, but in which clasts are still recognizable; typically the clasts are stretched or flattened.
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metaconglomerate
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The region around a pluton, stretching tens to hundreds of meters out, in which heat transferred into the country rock and metamorphosed the country rock.
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metamorphic aureole
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A set of metamorphic mineral assemblages indicative of metamorphism under a specific range of pressures and temperatures.
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metamorphic facies
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A fabric defined by parallel surfaces or layers that develop in a rock as a result of metamorphism; schistocity and gneissic layering are examples.
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metamorphic foliation
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An informal designation of the degree to which a rock has undergone metamorphism; high-grade rocks have endured higher temperatures than low-grade rocks.
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metamorphic grade
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A mineral formed by solid-state transitions under metamorphic conditions.
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metamorphic mineral
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Rock that forms when preexisting rock changes into new rock as a result of an increase in pressure and temperature and/or shearing under elevated temperatures; metamorphism occurs without the rock first becoming a melt or a sediment.
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metamorphic rock
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The arrangement of grains (e.g., preferred orientation) formed as a result of metamorphism.
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metamorphic texture
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The region between two metamorphic isograds, typically named after an index mineral found within the region.
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metamorphic zone
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The process by which one kind of rock transforms into a different kind of rock.
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Metamorphism
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The process by which a rocks overall chemical composition changes during metamorphism because of reactions with hot water that bring in or remove elements.
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Metasomatism
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A fine-grained metamorphic rock with a foliation caused by the preferred orientation of very fine-grained mica.
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phyllite
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The metamorphic texture that exists where platy grains lie parallel to one another and/or elongate grains align in the same direction.
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preferred mineral orientation
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The original rock from which a metamorphic rock formed.
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protolith
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A metamorphic rock composed of quartz and transformed from a protolith of quartz sandstone.
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quartzite
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Metamorphism of a broad region, usually the result of deep burial during an orogeny.
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regional metamorphism
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A medium- to coarse-grained metamorphic rock that possesses schistosity.
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schist
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An older, interior region of a continent.
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shield
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Solid-state changes in rock that result from the extreme pressure accompanying a meteorite impact.
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shock metamorphism
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Fine-grained, low-grade metamorphic rock, formed by the metamorphism of shale.
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slate
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Metamorphism caused by heat conducted into country rock from an igneous intrusion.
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thermal metamorphism
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The remarkable diversification of life, indicated by the fossil record, that occurred at the beginning of the Cambrian Period.
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Cambrian explosion
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A radiometric dating process that can tell us the age of organic material containing carbon originally extracted from the atmosphere.
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carbon-14 (14C) dating
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The boundary surface between two rock bodies (as between two stratigraphic formations, between an igneous intrusion and adjacent rock, between two igneous rock bodies, or between rocks juxtaposed by a fault).
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contact
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The process of defining the age relations between the strata at one locality and the strata at another.
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correlation
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A means of determining the relative age of rock by looking at which rock or structure cuts another; the feature that has been cut is older.
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cross-cutting relations
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The decay product of radioactive decay.
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daughter isotope
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The largest subdivision of geologic time.
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eon
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An interval of geologic time representing the largest subdivision of a period.
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Epoch
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An interval of geologic time representing the largest subdivision of the Phanerozoic Eon.
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era
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The principle that the assemblage of fossil species in a given sequence of sedimentary strata differs from that found in older sequences or in younger sequences; a given species appears at a certain level and then disappears (goes extinct) at a higher level.
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fossil succession
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A composite stratigraphic chart that represents the entirety of the Earth’s history.
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geologic column
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A map showing the distribution of rock units and structures across a region.
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geologic map
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The span of time since the formation of the Earth.
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geologic time
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A scale that describes the intervals of geologic time.
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geologic time scale
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The time it takes for half of a group of a radioactive element’s isotopes to decay.
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half-life
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Different versions of a given element that have the same atomic number but different atomic weights.
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isotope
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The science of dating geologic events in years by measuring the ratio of parent radioactive atoms to daughter product atoms.
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isotopic dating
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The age of a rock or structure as specified in years; referred to as Òabsolute ageÓ in older literature.
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numerical age
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The principle that sediments are deposited in nearly horizontal layers.
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original horizontality
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A radioactive isotope that undergoes decay.
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parent isotope
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An interval of geologic time representing a subdivision of a geologic era.
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period
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The interval of geologic time between Earth’s formation about 4.57 Ga and the beginning of the Phanerozoic Eon 542 Ma.
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Precambrian
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The process by which a radioactive atom undergoes fission or releases particles thereby transforming into a new element.
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radioactive decay
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The age of one geologic feature with respect to another.
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relative age
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A cross-section diagram of a sequence of strata summarizing information about the sequence.
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stratigraphic column
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A recognizable layer of a specific sedimentary rock type or set of rock types, deposited during a certain time interval, that can be traced over a broad region.
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stratigraphic formation
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The principle that younger layers of sediment are deposited on older layers of sediment; thus, in a sequence of strata, the oldest layer is at the base.
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superposition
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A boundary between two different rock sequences representing an interval of time during which new strata were not deposited and/or were eroded.
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unconformity
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The principle that the same physical processes observed today are responsible for the formation of ancient geologic features; put concisely, Òthe present is the key to the past.Ó
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uniformitarianism
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Which statement is true?
A. A saprolite layer is typically found in cold, dry climates. B. Pieces of broken rock produced by physical weathering are collectively called detritus. C.Animal attack, whether by gopher or man, is termed spalling. D.All of the above are true. E.Hydrolysis is the absorption of water into crystal structure and its subsequent expansion. htt s://webcam us.nevada.edu/webct/urw/t 46264695816011.lc45533001041081/ViewSt... 3/13/2013 |
B
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Choose the proper listing of detritus terms, going from smallest to largest of the words offered.
A.mud, silt, sand B.sand, cobbles, pebbles C.silt, mud, sand D.mud, sand, silt E.sand, silt, pebbles |
A
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Sedimentary rocks can form:
A.by the cementing together of loose grains of preexisting rock." B.by the precipitation of minerals from water solution. C.all of the above are true. D.from shell fragments or carbon-rich relicts of plants. E.only A and B are true. |
A
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Which is not a "soil term"?
A.arkose" B.caliche (calcrete) C.regolith D.bauxite E.laterite |
A
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A nonmarine clastic sedimentary rock composed of angular fragments surrounded by matrix is:
A.turbidite." B.arkose. C.fossiliferous limestone. D.conglomerate. E.breccia. |
E
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A clastic sedimentary rock with clay and silt-sized grains that breaks in thin sheets is called:
Student Response Correct Answer A.siltstone. B.graywacke. C.mudstone. D.micrite. E.shale. htt s://webcam us.nevada.edu/webct/urw/t 46264695816011.lc45533001041081/ViewSt... 3/13/2013 |
E
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Which term has nothing to do with the mineral calcite?
"Student Response Correct Answer A.fossiliferous limestone" B.micrite C.chalk D.chert E.aragonite |
D
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The organic sedimentary rock that is composed of mud-sized particles and partially decayed organic matter derived from plankton and algae remains is:
A.dolostone B.fossiliferous limestone. C.coal. D.oil shale. E.chert. |
D
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Which statement is true?
A.Flint, jasper, agate, and petrified wood are all varieties of the siliceous rock chert. B.Chemical sedimentary rocks are crystalline in texture. C.Both chert and limestone may have either chemical or biochemical origin. D.All of the above are true statements. E.Gypsum and halite are evaporite minerals. |
D
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Ripple marks on a bedding plane:
A.suggest you're looking at an old delta B.could suggest an ancient stream bed or a seashore. C.are a sure sign the area had periodic drought. D.are parallel to the current direction that created them. E.all of the above are true. |
B
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What is the most logical past environment to have produced a deposit
consisting of layers of well-sorted sandstone with cross beds several meters high? A.alluvial fan along a mountain front B.small-lake environment C.shallow-water carbonate area D.glacial valley E.sand dunes |
E
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What is the most logical past environment to have produced a deposit consisting of layers of unsorted, unstratified sedimentary clasts, clay-sized to boulder-sized?
A.sand dunes B.glacial valley C.floodplain D.shallow-water carbonate area E.small-lake environment |
B
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What is the most logical past environment to have produced a deposit consisting of very little sand and mud, but instead lots of broken-up carbonate shells of marine organisms?
A.shallow-water carbonate area B.delta C.glacial valley D.small-lake environment E.sand dunes |
A
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The structure that may form where a stream enters a lake:
A.has nearly horizontal topset beds composed of gravel. B.is called a delta. C.has nearly horizontal silty bottomset beds on the lake floor. D.has sloping forset beds of gravel and sand. E.all of the above are true statements. |
E
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Which of the following sedimentary features is the surest indicator that the past environment
there was subaerial (under air), not submarine (underwater)? A.mud cracks B.scour marks C.They are all indicators of a subaerial land surface. D.turbidites E.fossil marine clam shell imprints |
A
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Sedimentary rocks form only at or near Earth's surface, never at great depths.
a.True b.False |
A
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The words weathering and erosion are synonyms; they can be used interchangeably.
a.True b.False |
B
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Graywacke and conglomerate are examples of well-sorted rocks; shales and fine-grained sandstone are examples of poorly sorted rocks.
a.True b.False |
B
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A rock with large, angular fragments and lots of feldspar is classified as immature; a rock with smaller, rounded grains and not much feldspar is classified as mature.
a.True b.False |
A
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The formation of dolostone, due to the introduction of magnesium into limestone, is an example of diagenesis.
a.True b.False |
A
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The presence of redbeds indicates the sediments lithified in water and this caused the iron to rust.
a.True b.False |
B
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Diagenesis and metamorphism both alter the texture and mineral composition of rock; metamorphism is the more extreme process.
a.True b.False |
A
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A sequence of sedimentary beds, distinctive enough to be recognized as a unit called a stratigraphic formation, gives clues to the past environment that produced it.
a.True b.False htt s://webcam us.nevada.edu/webct/urw/t 46264695816011.lc45533001041081/ViewSt... 3/13/2013 |
A
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What is the protolith of marble?
A.gypsum B.chert C.quartz sandstone D.limestone E.phyllite |
D
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Identify the false statement. Hydrothermal fluids:
A.are chemically active solutions, not pure water. B.change a rock's chemical composition, a process known as exhumation. C.can be derived from groundwater or magma, or can be the product of metamorphic reactions. D.can pick up some dissolved ions and drop off others as they circulate through a rock. E.may consist of hot water, steam, and supercritical fluid. |
B
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Which of the following statements is false? A metamorphic rock:
A. may have developed metamorphic texture of interlocking grains. B.cannot be formed below 1200 °C. C.may be composed of different minerals than its protolith. D.may have preferred mineral orientation caused by differential stress. E.took thousands to millions of years to develop. |
B
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Which of the following statements is false? Extremely high heat of metamorphism:
A.causes mica to react, lose its identity, and become feldspar or some other water-free mineral. B.is necessary to elongate the large clasts in conglomerate to make flattened-clast conglomerate (metaconglomerate). C.drives off water, causing high-grade metamorphic rocks to be drier than low grade. D.may be as high as 1200 °C. E.is necessary to form migmatite. |
B
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Mylonite:
A.forms due to dynamic metamorphism. B.all of the above are true statements. C.forms by recrystallization in a fault zone. D.is produced by shear stress on softened rock. E.has pronounced foliation parallel to the direction of faulting. |
B
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Pick out the rock that is nonfoliated.
A.gneiss B.slate C.schist D.phyllite E.hornfels https://webcampus.nevada.edu/webct/urw/tp46264695816011.lc45533001041081/ViewSt... 3/ 13/ 2013 |
E
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Quartzite:
A.breaks around the separate grains of quartz that make it up. B.all of the above are true statements. C.always shows strong compositional banding. D.is always either white or gray. E.is basically a solid mass of interlocking quartz crystals. |
E
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Which of the following statements is false? Metamorphic facies:
A.are more reliable indicators of metamorphic conditions than index minerals are. B.are subdivided into seven major categories. C.each contain several metamorphic rock types with different mineral content. D.are sets of metamorphic mineral assemblages indicative of specific ranges of pressure and temperature. E.are identical to metamorphic mineral assemblages. |
E
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Which of the following statements about metamorphic rocks and their characteristic environments is true?
A.All of the above. B.Mylonites are found along convergent plate boundaries where magma is rising. C.Gneiss is found in metamorphic aureoles surrounding plutons. D.Slate, phyllite, schist, and gneiss are found in areas of continental collision. E.Blueschists are found in the mid-ocean ridge. https://webcampus.nevada.edu/webct/urw/tp46264695816011.lc45533001041081/ViewSt... 3/ 13/ 2013 |
D
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Which of the following statements is false? Shields:
A.are composed of extensive areas of sedimentary layers laid down on lava flows. B.are composed of the oldest rock on Earth. C.are composed of rocks that were metamorphosed during Precambrian mountain-building events. D.are large areas where the ground surface is metamorphic rock. E.make up large areas of Canada, northern Europe, and South America. |
A
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Which is not a common process by which metamorphic rocks are formed?
A.phase change B.recrystallization C.plastic deformation D.pressure solution E.schistosity |
E
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Mountain building due to convergent-margin tectonics and to continental collision:
A. all of the above are true. B.metamorphoses the once-surface rock by increasing its temperature due to igneous activity and to the geothermal gradient. C.sends surface rock to great depths under the new mountain. D.metamorphoses the once-surface rock by increased pressure due to the overburden’s weight. E.metamorphoses the once-surface rock by differential stress generated by plate interactions. https://webcampus.nevada.edu/webct/urw/tp46264695816011.lc45533001041081/ViewSt... 3/ 13/ 2013 |
A
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Recrystallization occurs because thermal energy causes atoms to vibrate rapidly, break existing chemical bonds, and migrate to new positions on the crystal lattice where they are more stable under the hotter conditions.
a. True b. False |
A
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Roofers use the rock schist to shingle roofs because its foliation, called schistosity, causes it to break in convenient size.
a. True b. False |
B
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Schist may form from a variety of protoliths that contain atoms necessary to make mica.
a. True b. False |
A
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Foliation and folding in metamorphic rock like gneiss happen slowly, over hundreds of thousands of years, as huge masses of softened rock flow slowly and at differential speeds within the mass.
a. True b. False https://webcampus.nevada.edu/webct/urw/tp46264695816011.lc45533001041081/ViewSt... 3/ 13/ 2013 |
A
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Quartzite is a favorite material of sculptors because of its uniform texture, wide range of colors, and relative softness.
a. True b. False |
B
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Metamorphic zones are regions between isograds named after the index minerals that occur within them.
a. True b. False |
A
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Blueschist is a common metamorphic rock of continental shields.
a. True b. False |
B
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Metamorphic aureoles typically contain nonfoliated rock like hornfels, because the pluton intrusion provides heat but not the shearing stress necessary for foliation.
a. True b. False https://webcampus.nevada.edu/webct/urw/tp46264695816011.lc45533001041081/ViewSt... 3/ 13/ 2013 |
A
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In the United States you can see Precambrian metamorphic rocks in places where rivers have sliced deeply into Earth's surface, such as in the Grand Canyon.
a. True b. False |
A
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When geologists say metamorphic grade, they're referring to the amount of metamorphic change, which depends primarily on the temperature involved; when they say facies, they mean the mineral assemblage
(mineral contents) of the rock. a. True b. False |
A
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Dynamothermal metamorphism (regional metamorphism) produces nonfoliated metamorphic
rocks in the depths of mountain ranges which erosion eventually exposes as “mountain roots” hundreds of kilometers wide and thousands of kilometers long. a. True b. False https://webcampus.nevada.edu/webct/urw/tp46264695816011.lc45533001041081/ViewSt... 3/ 13/ 2013 |
B
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Uniformitarianism:
A.is illustrated by scientists' seeing pillow lava form only under water, then theorizing that pillow lava found high in the mountains today did nevertheless form under water B.means neither the scientific past nor future should be predicted because physical laws change over time. C.is an idea that was formulated by the great physicist Becquerel in about 1900. D.means Earth's surface-its oceans, continents, and atmosphere-have always been the same and always will be the same. E.is an outdated theory that states catastrophes like major volcanic eruptions no longer happen. |
A
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Which of the following shows four time divisions listed from oldest to youngest?
A.Phanerozoic, Precambrian, Mesozoic, Cenozoic" B.Precambrian, Mesozoic, Archean, Cenozoic C.Archean, Paleozoic, Hadean, Proterozoic D.Hadean, Cenozoic, Mesozoic, Proterozoic E.Precambrian, Paleozoic, Mesozoic, Cenozoic |
E
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Choose the proper listing of names to fit the following three descriptions: Age of Mammals, Age of Dinosaurs, and longest geologic time period.
A.Cenozoic, Mesozoic, Precambrian B.Cenozoic, Hadean, Paleozoic C.Mesozoic, Cenozoic, Paleozoic D.Mesozoic, Cenozoic, Proterozoic E.Phanerozoic, Mesozoic, Precambrian |
A
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Which of the following is not a method to determine numerical age?
A.Dendrochronology B.carbon-14 dating C.cross-cutting relations D.radioactive decay of uranium to lead E.fission-track dating |
C
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Which of the following statements is false?
A.Varieties of an element that differ only in the number of neutrons are called isotopes. B.A formation is the name of a rock layer identified by such factors as rock type and approximate geologic age. C.If there are several layers of sedimentary rock, the oldest layer of rock will be on the bottom. D.An unconformity is a break in the rock record that indicates the area was under water for millions of years. E.The generally accepted age of Earth is 4.57 billion years. |
D
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Which of the following statements is false? On the diagram shown:
A.the area under the curve represents the amount of parent material present. B.there are equal amounts of parent and daughter material present after the passage of two half-lives. C.the ratio of parent to daughter isotopes changes with the passage of each successive half-life. D.if 2 g of parent material are present after three half-lives, there will also be 14 g of daughter material present. E.if the half-life of the parent material is 4,000 years, 3 on the horizontal axis of the graph represents 12,000 years. |
B
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Which of the following statements is false? The principle of:
A.original horizontality says sedimentary layers started out flat. B.original continuity says sedimentary layers began as continuous expanses of sediment. C.inclusions says rock containing inclusions is older than the inclusions. D.cross-cutting relations says the feature doing the cutting is younger than the feature it cuts. E.superposition says in a sequence of sedimentary beds, the youngest is on top. |
C
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A rock is given a radiometric date of 300,000,000 years, with an
uncertainty of measurement of 1%. This means the rock's age: A.has a 1% chance of being 300,000,000 years old. B.is anything between 3,000,000 and 300,000,000 years old. C.is anything between 3,000,000 and 303,000,000 years old. D.will remain unknown; there's only a 1% chance any date given will be correct. E.is anything between 297,000,000 and 303,000,000 years old. https://webcampus.nevada.edu/webct/urw/tp46264695816011.lc45533001041081/ViewSt... 3/ 13/ 2013 |
E
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An area of slightly dipping sedimentary rock layers has large inclusions and is intruded by an igneous dike. Apply the basic principles for determining relative ages and identify the false statement.
A.The inclusions are younger than the sedimentary rock they are in. B.The oldest sedimentary layer is the bottom layer. C.The igneous intrusion "baked" (metamorphosed) the sedimentary rock it touched. D.The sedimentary layers started out lying flat. E.The dike is younger than the sedimentary rock layers it cuts across. |
A
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Identify the false statement.
A.William Smith noted the similarities of rock layers and fossil assemblages at different locations, which led to the process of correlation. B.Charles Lyell correctly explained how fossils form and formulated some of the basic principles of relative dating. C.James Hutton, the father of geology, introduced the principle of uniformitarianism. D.Henri Becquerel and Ernest Rutherford applied principles of radioactivity to determine Earth's age. E.Archbishop James Ussher added up generations of patriarchs in the bible and concluded the birth date of Earth was October 23, 4004 B.C.E. https://webcampus.nevada.edu/webct/urw/tp46264695816011.lc45533001041081/ViewSt... 3/ 13/ 2013 |
B
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Identify the false statement. Radiometric dating:
A.can be used only if there's some uranium present in the rock. B.can give ages with uncertainties as small as 0.1%. C.can begin only when the isotopes cool enough to lock into the crystal lattice. D.of sedimentary rock dates the time of crystallization of the sedimentary minerals, not the time of sedimentary rock formation. E.of metamorphic rock tells when the high temperatures of metamorphism cooled below the blocking temperatures of the minerals involved. |
A
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A radioactive isotope of the element potassium decays to produce argon. If the ratio of argon to potassium is found to be 7:1, how many half-lives
have occurred? A.1 half-life B.3 half-lives C.7 half-lives |
B
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Charcoal (burned wood) that was used to make prehistoric drawings on cave walls in France was scraped off and analyzed. The results were 4 mg
carbon 14 (parent isotope) and 60 mg nitrogen (daughter isotope). The half-life of carbon 14 is 5,730 years. How old are the cave drawings? A.17,190 years B.22,920 years C.The sample is too old to be analyzed by carbon dating. D.11,460 years |
B
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On the diagram shown, several surfaces between rock layers are identified by letters. Choose the answer below that correctly identifies the unconformities.
A.C and E B.B and E C.A and E D.C and D |
A
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Identify the false statement. William Smith’s observations:
A.were made around 1800 in fresh exposures of sedimentary bed rock in the English countryside. B.noted that a fossil species could disappear, then reappear in much younger strata. C.lead to the principal of fossil succession. D.recognized that fossil species progressed from older at the bottom to younger at the top of sedimentary strata. E.recognized that groups of fossil species (fossil assemblages) occurred in limited intervals of strata. |
B
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In 1815, William Smith correlated strata from many locations and plotted it on paper to show the spatial distribution of rock units on Earth’s surface. This document was the first modern:
A.geologic time scale. B.stratigraphic column. C.range. D.geologic map. E.geologic column. https://webcampus.nevada.edu/webct/urw/tp46264695816011.lc45533001041081/ViewSt... 3/ 13/ 2013 |
D
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A disconformity is a type of unconformity in which sedimentary rocks overlie either igneous or metamorphic rocks.
a. True b. False |
B
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If you equate all Earth history to one calendar year, all recorded human history occupies the week from Christmas to New Year's Eve.
a. True b. False |
F
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It's not possible to say just when an individual radioactive atom will decay, but it is possible to say when half of an existing quantity of
radioactive material will be gone. a. True b. False |
A
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Correlation matches up rock layers across distances on the basis of similar sequences of rock layers and similar fossils in the layers.
a. True b. False https://webcampus.nevada.edu/webct/urw/tp46264695816011.lc45533001041081/ViewSt... 3/ 13/ 2013 |
A
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Correlation matches up rock layers across distances on the basis of similar sequences of rock layers and similar fossils in the layers.
a. True b. False https://webcampus.nevada.edu/webct/urw/tp46264695816011.lc45533001041081/ViewSt... 3/ 13/ 2013 |
A
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The boundary surface between two stratigraphic formations is called a key bed.
a. True b. False |
B
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Numerical (or absolute) dating is just a comparison of age; relative dating assigns numbers.
a. True b. False |
B
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The first half-life period of carbon-14 is 5,730 years; the second half-life period of carbon-14 is half of this, and the number of years is cut in half for each succeeding half-life period.
a. True b. False |
B
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Eighteenth- and nineteenth-century scientists tried to determine Earth's age by analyzing the thickness of sediments, the saltiness of oceans, and Earth's temperature, but crucial flaws in these techniques gave incorrect ages.
a. True b. False |
A
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The largest subdivision of time on the geologic column are eras, which are broken down into smaller units called eons, then periods, then epochs.
a. True b. False Student Response Correct Answer A.True B.False |
B
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4.57 billion-year-old moon rock and meteorites are the oldest rocks found in our solar system, leading geologists to conclude this is the approximate age of the Earth.
a. True b. False |
A
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Fragments of igneous material that have been stuck together to form a coherent mass.
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fragmental igneous rock.
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A coarse-grained igneous rock containing crystals of up to tens of centimeters across and occurring in dike shaped intrusions.
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Pegmatite
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Rock made from fragments blown out of a volcano during an explosion that were then packed or welded together.
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Pyroclastic rock.
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A rock composed of angular chunks of volcanic debris that have been cemented together.
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Breccia
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Which of the following statements is false? Igneous rocks:
a. are termed phaneritic if they're fine grained. b. are coarse-grained if they're intrusive c. form in great quantities along the mid-ocean ridge. d. were the first rocks to exist on earth. e. form from the freezing of either lava or magma |
Which of the following statements is false? Igneous rocks:
--- a. are termed phaneritic if they're fine grained. b. are coarse-grained if they're intrusive c. form in great quantities along the mid-ocean ridge. d. were the first rocks to exist on earth. e. form from the freezing of either lava or magma |
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Which of the following igneous rocks does not have a glassy texture?
a. obsidian b. scoria c. tachylite d. pegmatite e. pumice |
Which of the following igneous rocks does not have a glassy texture?
a. obsidian b. scoria c. tachylite d. pegmatite --- e. pumice |
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Which of the following statements is false? Felsic magma:
a. has about 70% silica and little magnesium and iron b. is less viscous than mafic magma c. is associated with explosive volcanic eruptions. d. is likely to form light tan, pink, or maroon-colored rocks. e. is the coolest of magmas. |
Which of the following statements is false? Felsic magma:
a. has about 70% silica and little magnesium and iron --- b. is less viscous than mafic magma c. is associated with explosive volcanic eruptions. d. is likely to form light tan, pink, or maroon-colored rocks. e. is the coolest of magmas. |
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Which of the following statements is false? Mafic minerals:
a. form rhyolite and granite b. are those rich in iron and magnesium c. would be at the top of the Bowen's reaction series, crystallizing first out of the melt. d. freeze at a higher temperature than silicic minerals do e. form black or dark-gray rocks. |
Which of the following statements is false? Mafic minerals:
--- a. form rhyolite and granite b. are those rich in iron and magnesium c. would be at the top of the Bowen's reaction series, crystallizing first out of the melt. d. freeze at a higher temperature than silicic minerals do e. form black or dark-gray rocks. |
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Phaneritic - Def
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A coarse-graned rock with visible crystals. (intrusive)
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Pegmatitic - def
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a sub-category of phaneritic rocks. Pegmatites are igneous rocks that contain crystals that are at least 1 inch in size (intrusive).
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Aphanitic - def
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a fine-grained rock composed of crystals that are too small to see with the naked eye. (extrusive).
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Porphyritic - def
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large crystals are embedded in a fine-grained (aphanitic) background. involves some cooling below the Earth's surface followed by extrusion at a surface (extrusive).
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Vesicular - def
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an aphanitic rock that contains roughly spherical, or partially rounded cavities called vesicles. Gas bubbles that were trapped in the magma during cooling are responsible for the vesicles (extrusive).
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Frothy - def
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a vesicular rock that is mostly cavities; i.e., there are more bubbles than rock (extrusive). Rocks with a frothy texture are unusually light, and will often float on water.
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categorized on the basis of mineral composition and texture.
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Igneous rocks
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Mineral compositions of igneous rocks
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felsic
intermediate, mafic ultramafic |
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Texture of igneous rocks
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extrusive
intrusive |
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Texture of an igneous rock is determined by:
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Texture of an igneous rock is determined by the size of a typical mineral crystal in the rock, and the distribution of sizes that are present; mainly dependent on the rate at which the liquid magma was cooled.
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Extrusive or Intrusive
(Tiny grains and non-crystalline glass) or large crystals able to be seen with the eye. |
Extrusive - Tiny grains and non-crystalline glass)
Intrusive - large crystals able to be seen with the eye. |
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Glassy - def
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looks like glass and often exhibits conchoidal fracture. Because glass lacks crystalline structure, rocks with a glassy texture do not contain minerals. Results from extremely rapid cooling (extrusive).
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Felsic Mineral Composition of igneous rocks - def
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light-colored rocks that are mostly (>80%) composed of feldspar and silica. n addition to being light colored, felsic rocks usually have a density similar to quartz, which is relatively light. The most common felsic rock is granite, which is intrusive; rhyolite is the chemical equivalent of granite, but it is extrusive.
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Mafic Mineral Composition of igneous rocks - def
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dark-colored rocks that contain high percentages of magnesium and ferric minerals, where ferric means that the minerals contain iron. Mafic rocks are generally denser than felsic rocks due to the presence of iron. The most common mafic rock is basalt, which is extrusive; gabbro is the chemical equivalent of basalt, but it is intrusive.
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1. Intrusive Mafic
2. Extrusive Mafic |
1. Intrusive Mafic - Gabbro
2. Extrusive Mafic - Basalt (most common) |
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1. Intrusive Felsic
2. Extrusive Felsic |
Intrusive Felsic - granite (most common)
Extrusive Felsic - rhyolite |
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Intermediate Mineral Composition of igneous rocks - def
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grey, greenish, or salt and pepper colored rocks that contain roughly equal amounts of mafic and felsic minerals. The most common intermediate rock is andesite, which is extrusive; diorite is the intrusive equivalent of andesite.
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1. Intrusive Intermediate
2. Extrusive Intermediate |
Intrusive Intermediate - andesite (most common)
Extrusive Intermediate - diorite |
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Igneous rock identifying steps
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1. Determine if it is igneous, sedimentary, or metamorphic.
2. Define the cooling mechanism as extrusive or intrusive. 3A. Intrusive - ID specific minerals and decide if the texture is phaneritic or pegmatititc. 3B. Extrusive - A small magnifying glass may be of assistance of ID minerals, however, you may have to make assumptions based on color and/or relative density. |
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a
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a
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