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115 Cards in this Set
- Front
- Back
Mixture of gas and pyroclastic debris that is so dence that it hugs the ground
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Pyroclastic flow
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A fluids resistence to flow
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viscosity
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Opening through which lava erupts
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vent
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Small, steeply sloped, composed of pyroclatic fragments ejected from a central vent
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cinder cones
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Very fluid (basalts), dose not build cone or volcano, large in volume, andcreates lava plateaus
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flood eruptions
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Layers of basalt flows that have built up to a great thickness
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plateau basalts
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Volcanic glass
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obsidian
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Intermediate composition volcanic rock
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andesite
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Basinlike depresin over a vent at the summit of the cone
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crater
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Moderately to steeply sloped, composed prodomenty of andesites, most common at convergence plate boundaries
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composite volcanos
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Nearly always basalt, mid-ocean ridge eruptions, pilow basalts
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submarine eruptions
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Type of mudflow composed of pyroclastic material and water that flows down from a volcano
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lahar
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Rapidly cooled rock fragments
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pyroclasts
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Gental slopes formed due to low viscosity of lava. commly associated with sheild volcanos
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mafic magma
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Volcaic depreion much larger then original crater, having a diameter of at least 1km
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caldera
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Hill or mountain formed by the extrusion of lava or ejection of rock fragments from a vent
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volcano
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Broad and gently sloping due to low viscosity of lava, contain lava tubes
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shield volcanos
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Steep-sided, dome, or spine-shaped masses of volcanic rock (viscous lava) that solidifies in or immediately above a volcanic vent or crater
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volcanic dome
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Frothy volcanic glass that floats in water
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pumice
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spewed 6 cubic miles of rock
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Krakatoa
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35,000 people killed
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Krakatoa
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high silica; light color
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Rhyolite
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low silica; dark color
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Basalt
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glass without mineral crystals
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Glassy
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most crystals < 1 mm
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Fine-grained
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larger crystals in a matrix of much finer crystals or glass
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Porphyritic
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originally created from gases released by magmas
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Atmosphere
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produced by condensation of volcanic water vapor
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Hydrosphere
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group of destructive processes that change physical and chemical character of rocks at or near Earth’s surface
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weathering
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Mechanic effect of freezing (and expanding) water on rocks
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frost action
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Decomposition of rock from exposure to atmospheric gases
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chemical weathering
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Highly leached and unproductive soils
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laterites
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physical picking up of rock particles by water, ice, or wind
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erosion
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Removal of overlying rock allowing for expansion and fracturing
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pressure release
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Chemically active oxygen from atmosphere cuases
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oxidation
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any layer of firm detrital matter, as of clay, underlying soft soil
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hardpan
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the movement of eroded particles by water, ice, or wind
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transportation
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granite subsequently erodes in concentric layers (similar to the way an onion peels) forming rounded masses
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exfoliation domes
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Hydrogen cations replace others in minerals
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acid dissolution
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Frost action, pressure-release fracturing, plant growth, burrowing animals, salt wedging, thermal cycling
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mechanical weathering
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Large temperature changes fracture rocks by repeated expansion and contraction
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thermal cycling
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a layer of weathered, unconsolidated material on top of bedrock
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soil
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weathering of underlying rock
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Residual soil
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brought in from elsewhere
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Transported soil
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rocks produced from rock fragments
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detrital rocks
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produced by precipitation of dissolved ions in water
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chemical rocks
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produced by accumulation of biological debris, such as in swamps or bogs
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organic rocks
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features found wihin sedimentary rock
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sedimentary structures
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loose, solid particles
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sediment
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shift to a tighter packing, with a resulting decrease in pore space
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compaction
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composed of rounded gravel cemented together
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conglomerate
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Slightly coarser-grained than shales
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siltstone
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occurs due to abrasion during transport
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rounding
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Chemical precipitates of material in the space between sediment grains, binding the grains together into a hard rock
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cementation
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Medium-grained clastic sedimentary rock
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sandstone
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Predominantly clay-sized grains; non-fissile
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claystone
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Silt- and clay-sized grains; massive/blocky
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mudstone
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Fine-grained clastic sedimentary rock
Splits into thin layers (fissile) Silt- and clay-sized grains |
shale
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Hard, compact, fine-grained, formed almost entirely of silica
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chert
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occurs as sediment is separated according to grain size by transport agents, especially running water
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sorting
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open space between grains
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pore space
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the location in which deposition occurs
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environment of deposition
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composed of coarse, angular rock fragments cemented together
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sedimentary breccia
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sand grains surrounded by dark, fine-grained matrix, often clay-rich
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greywacke
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composed mainly of calcite
Most are biochemical, but can be inorganic Often contain easily recognizable fossils |
limestone
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Sedimentary rock forming from compaction
of partially decayed plant material |
coal
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Form from evaporating saline waters
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Evaporites
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Series of visible layers within a rock
Most common sedimentary structure |
bedding plane
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Series of thin, inclined layers within a horizontal bed of rock
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Cross-bedding
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Small ridges formed on surface of sediment layer by moving wind or water
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Ripple marks
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Progressive change in grain size from bottom to top of a bed
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Graded bedding
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Polygonal cracks formed in drying mud
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Mud cracks
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Traces of plants or animals preserved in rock
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fossils
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General term for processes converting loose sediment into sedimentary rock
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lithification
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solid-state changes to rocks in Earth’s interior
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metamorphism
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causes flattening perpendicular to stress
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compressive stress
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prduced when grains of quartz in sandstone are welded together while the rock is subject tohigh tempatures
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quartzite
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metamorphic rock characterized by coarse-gained minerals oriented approximately parallel
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schist
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parts of body move or slide relative to one another across a plane
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shearing
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a very fine-grained, nonfoliated, metamorphic rock whose parent rock is either shale or basalt
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hornfels
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produced by rapid application of extreme pressure
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Shock metamorphism
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Metamorphic rocks common in the old, stable cores of continents
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craton
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Metamorphic rock composed of light and dark layers or lenses
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gneiss
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Line or rock where the tempature of the rock is the same
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isotherm
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pre-existing rocks
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parent rock
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Planar rock texture of aligned minerals produced by differential stress
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foliation
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Fine-grained rock that splits easily along flat, parallel planes
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slate
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High temperature is dominant factor
Produces non-foliated rocks Occurs adjacent to magma bodies intruding cooler country rock Occurs in narrow zone (~1-100 m wide) known as contact aureole Rocks may be fine- (e.g., hornfels) or coarse-grained (e.g., marble, quartzite) |
contact metamorphism
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Partial melting during metamorphism produces
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migmatite
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Rocks precipitated from or altered by hot water
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hydrothermal
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Pressure aplied equallyon all surfaces of a body
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confining pressure
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Coarse-grained rock composed of interlocking calcite crystals
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marble
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Metamorphic rock in which clay minerals have recrystalized into microscopic micas, giving the rock a silky sheen
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phyllite
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High pressure is dominant factor
Results in rocks with foliated textures Prevalent in intensely deformed mountain ranges May occur over wide temperature range Higher pressure and temperature will produce increased metamorphic grade |
regional metamorphism
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Byproduct of shock metamorphism
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tektites
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same processes operating in past are operating at present
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actualism
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the age of events or objects, expressed as a number or numbers
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numerical(absolute)age
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the order of events or objects, from first (oldest) to last (youngest)
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Relative age
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beds of sediment
deposited in water are initially formed as horizontal or nearly horizontal layers |
original horizontality
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within an
undisturbed sequence of sedimentary or volcanic rocks, layers get younger from bottom to top |
superposition
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original horizontal layer extends
laterally until it tapers or thins at its edges |
lateral continuity
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a disrupted pattern is older than the cause of the disruption
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cross-cutting relationship
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a surface (or contact) that
represents a gap in the geologic record |
unconformity
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an unconformity in which the
contact representing missing rock layers separates beds that are parallel to each other |
disconformity
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an unconformity in which
the contact separates overlying younger layers from eroded tilted or folder layers |
angular unconformity
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an unconformity in which an erosion surface on plutonic or metamorphic rock has been covered by younger sedimentary or volcanic rock
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nonconformity
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determining the time-equivalency of rock units
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correlation
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Fossil species succeed one another through the layers in a predictable order
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faunal succession
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Fossil from which a very short-lived, geographically widespred species known to exist during a specific period of geologic time
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index fossil
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groups of different fossil species
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fossil assemblage
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Determining the age of a rock through its radioactive elements
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isotopic dating
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Spontaneous nuclear change of isotopes wth unstable nuclei
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radioactive decay
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time it takes for a given amount of radioactive isotope to be reduced by half
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half-life
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Youngest eon/current eon
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Phanerozoic
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Eon where life first appered
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Proterozoic
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