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68 Cards in this Set
- Front
- Back
rock cycle
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A model that illustrates the origin of the three basic rock types and the interrelatedness of earth's materials and processes.
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crust
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The very thin, outermost layer of Earth.
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mantle
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The 2885-Kilometer (1789-mile) thick layer of Earth located below the crust.
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core
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Located beneath the mantle, it is Earth's innermost layer.
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asthenosphere
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A subdivision of the mantle situated below the lithosphere.
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lithosphere
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The ridged outer layer of Earth, including the crust and upper mantle.
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lithospheric plate
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A coherent unit of Earth's rigid outer layer that includes the crust and upper mantle.
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plate tectonics theory
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The theory that proposes Earth's outer shell consists of individual plates, which interact in various ways and thereby produce earthquakes, volcanoes, mountains, and the crust itself.
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divergent boundary
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A boundary in which two plates move apart, resulting in upwelling of material from the mantle to create new seafloor.
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convergent boundary
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A boundary in which two plates move together.
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transform-fault boundary
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A boundary in which two plates slide past one another without creating or destroying lithosphere.
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mineral
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A naturally occurring, inorganic crystalline material with a unique chemical structure.
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valence electron
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The electron involved in the bonding process; the electrons occupying the highest principle energy level of an atom.
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atomic number
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The number of protons in the nucleus of an atom.
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mass number
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The sum of the numbers of neutrons and protons in the nucleus of an atom.
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isotopes
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Varieties of the same element that have different mass numbers; their nuclei contain the same number of protons but different numbers of neutrons.
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ionic bond
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A chemical bond between two oppositely charged ions formed by the transfer of valence electrons from one atom to another.
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covalent bond
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A chemical bond produced by the sharing of electrons.
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luster
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The appearance or quality of light reflected from the surface of a mineral. metallic or nonmetallic
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streak
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The color of a mineral in powdered form.
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hardness
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A mineral's resistance to scratching and abrasion.
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cleavage
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The tendency of a mineral to break along planes of weak bonding.
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density
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The weight per unit volume of a particular material.
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specific gravity
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The ratio of a substance's weight to the weight of an equal volume of water.
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silicon-oxygen tetrahedron
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A structure composed of four oxygen atoms surrounding a silicon atom that constitutes the basic building block of silicate minerals.
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ferromagnesian silicates
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Silicate minerals containing ions of iron and/or magnesium in their structure.
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magma
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A body of molten rock found at depth, including any dissolved gasses and crystals.
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extrusive
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Igneous activity that occurs at Earth's surface.
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intrusive
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igneous rock that formed below Earth's surface.
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aphanitic texture
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A texture of igneous rocks in which the crystals are too small for individual minerals to be distinguished with the unaided eye.
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vesicular texture
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A term applied to aphanitic igneous rocks that contain many small cavities.
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porphyritic texture
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An igneous rock texture characterized by two distinctively different crystal sizes.
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phenocryst
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Conspicuously large crystals in a porphyry that are imbedded in a matrix of finer-grained crystals.
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phaneritic texture
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An igneous rock texture in which the crystals are roughly equal in size and large enough so that individual minerals can be identified with the unaided eye.
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glassy texture
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A term used to describe the texture of certain igneous rocks, such as obsidian, that contains no crystals.
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pyroclastic texture
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An igneous rock texture resulting from the consolidation of individual rock fragments that are ejected during a violent eruption.
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felsic
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It is a term used to describe granitic igneous rocks.
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mafic
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Because basaltic rocks contain a high percentage of ferromagnesian minerals, they are called?
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ultramafic
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Category for igneous rocks made up almost entirely of ferromagnesian minerals.
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partial melting
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The process by which most igneous rocks melt.
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decompression melting
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Melting that occurs as rock ascends due to a drop in confining pressure.
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geothermal gradient
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The gradual increase in temperature with depth in the crust. the average is 30 degrees Celsius per kilometer in the upper crust.
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Bowen's reaction series
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illustrates the relationship between magma and the minerals crystallizing from it during the formation of igneous rock.
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crystal settling
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This process occurs when the earlier-formed minerals are denser than the liquid portion and sink toward the bottom of the magma chamber.
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magmatic differentiation
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The formation of one or more secondary magmas from a single parent magma.
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assimilation
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As magma migrates upward, it may incorporate some of the surrounding host rock.
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magma mixing
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This process occurs whenever one magma body intrudes another.
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viscosity
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A measure of a fluid's resistance to flow.
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shield volcanoes
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A broad, gently sloping volcano built from fluid basaltic lavas.
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cinder cones
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A rather small volcano built primarily of pyroclastics ejected from a single vent.
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composite cones
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A volcano composed of both lava flow and proclastic material.
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pyroclastic flows
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A highly heated mixture, largely of ash and pumice fragments, traveling down the flanks of a volcano or along the surface of the ground.
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lahars
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Mudflows on the slopes of volcanoes that result when unstable layers of ash and debris become saturated and flow downslope.
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calderas
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A large depression typically caused by collapse of the summit area of a volcano following a violent eruption.
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fissure eruptions
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An eruption in which lava is extruded from narrow fractures or cracks in the crust.
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flood basalts
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Flows of basaltic lava that issues from numerous cracks or fissures and commonly cover extensive area to thickness of hundreds of meters.
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lava domes
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A bulbous mass associated with an old-age volcano, produced when thick lava is slowly squeezed from the vent.
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volcanic necks
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An isolated, steep-sided, erosional remnant consisting of lava that once occupied the vent of a valcano.
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plutons
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A structure that results from the emplacement and crystallization of magma beneath Earth's surface.
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discordant
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A term used to describe plutons that cut across existing rock structures, such as bedding planes.
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concordant
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A term used to describe intrusive igneous masses that form parallel to the bedding of the surrounding rock.
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dikes
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A tabular-shaped intrusive igneous feature that cuts through the surrounding rock.
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sills
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A tabular igneous body that was intruded parallel to the layering of preexisting rock.
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laccoliths
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A massive, concordant igneous body intruded between preexisting strata.
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batholiths
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A large mass of igneous rock that formed when magma was emplaced at depth, crystallized, and was subsequently exposed to erosion.
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island arcs
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A chain of volcanic islands generally located a few hundred Kilometers from a trench where there is active subduction of one oceanic plate beneath another.
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mantle plume
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A mass of hotter-than-normal mantle material that ascends toward the surface, where it may lead to igneous activity.
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hot spot
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A proposed concentration of heat in the mantle capable of introducing magma that in turn extrudes onto Earth's surface.
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