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78 Cards in this Set
- Front
- Back
What is weathering?
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the process at the earth's surface that breaks down mineral and rocks
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What is erosion?
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transport of sediment formed from weathering
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What are the 2 basic types of weathering?
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mechanical and chemical
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What is mechanical weathering?
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breaks into smaller pieces but doesn't change chemical make-up (eg. freezing water)
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What is chemical weathering?
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converts to minerals and rocks stable at earth's surface
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True or false: all weathering occurs at earth's surface.
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false
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What are the different types of mechanical weathering?
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-frost wedging
-crystal growth -thermal expansion and contraction -mechanical exfoliation -other (plants, abrasion in streams, glaciers, and wind) |
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What is dissolution?
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-chemical weathering
-solution by water |
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What is oxidation?
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-chemical weathering
-combine with O2, Fe in silicate minerals |
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What is hydrolysis?
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-chemical weathering
-Al rich silicates (feldspars) going to clay. *yields soil |
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What affects weathering process speed?
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-climate (temp and presence of water --the higher the temp and more water, the faster reaction)
-living organisms (acids, burrowing, etc.) -time (glacial, old/new) -mineral composition (bonding olivine/quartz) |
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What are products of chemical weathering?
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-clay minerals (kaolinite, smectite--swelling clay, absorbs water)
-metal ores (bauxite) -minerals formed function of temp and water present |
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Soils upper surface of regolith (rock) - nature determined by:
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-parent material
-climate (temp and water) -topography (location, landforms) -vegetation -time |
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What is eluviation?
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water percolates down soil column, transporting organic material and soluble inorganic matter
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What is illuviation?
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materials transported from upper soil horizons are deposited
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Do limestone and quartz (sandstone) yield a lot of soil?
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no, very little
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Talk about CENEX.
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Washington State mixed its metallic waste in with fertilizer and sold it to farmers who applied it to their crops thru center-pivot irrigation systems
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Talk about ALCOA.
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saved $2 million by marketing its smelter waste as road de-icer in the winter and fertilizer in the summer.
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What is David R. Montgomery's book "Dirt: Erosion of Civilization" about?
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traces history of major civilizations and ties their decline to abuse of soil
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What makes up more than half of all sedimentary rocks?
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mudstones
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What are detrital sedimentary rocks?
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rocks formed from pieces of pre-existing rocks or organic debris
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What are sandstones?
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usually quartz and feldspars, when cemented can be very hard
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What is the difference between conglomerates and breccias?
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-conglomerates- if particles are rounded
-breccias- if particles are angular |
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What is limestone?
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-inorganic chemical sedimentary rock
-calcite precipitate from water, travertine, or tufa (springs) |
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What are stalactites and stalagmites?
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cave structures:
-stalactites go down -stalagmites go up |
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What are biogeneic limestones?
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-biogeneic chemical sedimentary rock
-CaCO3 shells and external skeletons, formed along shallow coast lines |
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What are biogeneic cherts?
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-biogeneic chemical sedimentary rock
-silica of raidolara, diatoms, and sponges |
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What is coal?
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-biogeneic chemical sedimentary rock
-mostly plant remains, buried and compacted in O2 poor environment |
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Name biogeneic chemical sedimentary rock (7).
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-biogeneic limestones
-biogeneic cherts -coal -peat -lignite -bituminous -anthracite |
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What are facies?
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a body of rock with specified characteristics.[1] Ideally, a facies is a distinctive rock unit that forms under certain conditions of sedimentation, reflecting a particular process or environment.
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What are the 2 types of sediment?
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-detrital (most are)
-chemical |
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What is detrital sediment?
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transported solid fragments weathered from pre-existing igneous, sedimentary, or metamorphic rocks
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What is chemical sediment?
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previously discovered either precipitate from solution or ore extracted from water by living organisms
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What are sedimentary structures (bedding)?
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arrangement of sediment particles into distinct layers of differing sediment compositions or grain sizes
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What is graded bedding?
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single sediment layer in which particle size varies
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What is cross bedding?
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sedimentary layered deposited at an angle to the underlying set of beds
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What are ripple marks?
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indicate that wind or water currents shaped the particles into a series of shallow curving ridges
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What is lithification?
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the conversion of loose sediment into solid sedimentary rock
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What is metamorphism of rock?
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process by which temperature, pressure, and chemical reactions deep within the earth alters the mineral content and structure of pre-existing rock with melting it
-usually round 1,000's of meters below earth's surface and seen only when uplift and erosion have stripped away overlying rocks |
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Where are rocks and minerals most stable?
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in the environment in which they form
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Rather than melting under increased heat and pressure to form magmas, metamorphism involves a transformation in the ________ ________.
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solid state
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Clays formed at earth's surface on heating will _______________________.
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recrystalize to form new minerals
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True or false: Quartz will change size and shpae but remain quartz.
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true
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What is geothermal gradient?
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heat increases within depths of earth
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Does pressure increase or decrease with depth?
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increase
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What are the 2 types of pressure?
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-lithostatic (directional)
-confining |
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What does directed pressure produce?
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foliation or parallelism of mineral grains
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What do circulating fluids do?
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-provide medium for movement of ions within rock
-contribute foreign ions to metamorphic reactions |
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Describe contact metamorphism.
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-caused by migrating magma- local effect
-heat of magmas -hot circulating fluids -pressure is not a significant factor -aureole - cm/m around dike, km batholith |
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Describe regional metamorphism.
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-thousands of km2
-buried metamorphism - 10 km nonfoliated, Gulf Coast area -dynamothermal metamophism - at core of most major mountains, typically foliated |
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What is hydrothermal metamorphism?
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chemical alteration by hot water- ocean ridges olivine to serpentine
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What is fault metamorphism?
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friction yielding heat and directed pressure. cold faults/ warm<-- if ground water circulates through
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What is shock metamorphism?
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meteorite, very high temp and pressures, unique mineral. stishovite
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What is pyrometamorphism?
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lightning or burning coal
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Name 4 foliated metamorphic rocks.
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-slate
-phyllite -schist -gneiss (increase heat and pressure as you go down) |
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Name 3 nonfoliated metamorphic rocks.
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-marble
-quartzite -hornfels (contact with hot magma) |
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Describe nonfoliated metamorphic rock.
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-no directional pressure
-deep burial or heat from magma -marble from pure limestone and dolomites -quartzite from pure quartz sandstones, very hard with quartz cement -hornfels- heat drives off mineral bond water in shales, slates or... |
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What is low metamorphic grade?
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can still identify rock
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What is high metamorphic grade?
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have lost all of their original structures
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True or false: One million years is virtually instantaneous in geologic time.
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true
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What is relative dating?
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-comparing layers (older layers = older)
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What is numerical dating?
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absolute dating
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What is uniformitarianism?
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present is the key to the past, have to consider how earth has evolved
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What is horizontally/ super-position?
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most sediment deposited from water is horizontal, so rocks on top are younger
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What is inclusion?
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fragments of rocks in a rock must be older
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What are unconformities?
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rock layers don't match but you know bottom is old
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What are the different types of relative dating?
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-uniformitarianism
-horizontally/super-position -cross-cutting |
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Describe numerical age - isotope.
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-radioactive isotopes- parent to daughter resulting in new element
-know that daughter element was not present in original mineral -rate of decay- different -isotopes more accurate for igneous rock -age of rock/rate of decay- may be difficult if weathering -although scores of isotopes only a few are useful for dating -C-14 - 100-70,000 years |
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What is fission track dating?
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-numerical technique
-decay particle leaves track in mineral - crystal, count tracks |
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What is dendrochronology?
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-numerical technique
-tree rings |
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What are varves?
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-can be used for numerical dating
-paired layers of sediment in lakes |
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What are lichen?
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-can be used for numerical dating
-size of lichen related to age |
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True or false: There are not distinct patterns representing droughts, fires, etc. shown in tree rings that can be correlated from tree to tree
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false
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What are the 2 types of isotopic numerical dating?
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-dating of rocks
-dating of organic matter |
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What are the 3 types of other numercial dating?
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-botanical growth rates
-geologic processes -nuclear processes |
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What are the 2 types of botanical growth rates for numerical dating?
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-lichenometry
-dendrochronology |
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What is the type of geological process for numerical dating?
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varve chronology
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What are the 2 types of nuclear processes for numerical dating?
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-fission track
-surface exposure (cosmogenic isotope) |