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60 Cards in this Set
- Front
- Back
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Detrital
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composed of mineral and rock fragments derived from a pre-existing rock.
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Grain size decreasing
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conglomerate
sandstone siltstone shale |
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Metamorphism
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all processes, operating well below the surface, which cause the recrystallization of pre-existing rock
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Rock cycle
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sed-meta-ig-sed
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Types of Metamorphic changes in rocks
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new minerals may form,
new textures form always grain size increases with increasing temp |
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Foliation
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planar structure may form
due to parallel alignment of flakey minerals |
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Causes of metamorphism
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temperature increase
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contact metamorphism
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intruding magma
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burial
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geothermal gradient 30 deg Celcius per km of depth
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confining pressure
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equal in all directions
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directed pressure
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in one direction
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regional metamorphism
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requires directed pressure and increase in temperature
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sources of water/steam
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in pores within sed rocks
in water bearing minerals in sed/ig rocks intruding igneous bodies |
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low intensity of meta
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fine grain
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high intensity of meta
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coarse grain
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equivalent of conglomerate
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metaconglomerate
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equiv of sandstone
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quartzite
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equiv of shale
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slate, schist
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equiv of limestone
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marble
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equiv of gabbro
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amphibolite
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field tracing
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metamorphic rock into the original rock. comparing the chemical composition of the meta rock with that of various sedimentary and ig rock types
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relative time
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order in which events took place
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absolute time
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age of events in number of years
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original horizontality
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surficially-deposited rocks form as horizontal layers initially, if now deformed then the deformation is younger
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superposition
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surficially-deposited rocks are younger upward
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cross-cutting relationships
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intrusions, faults and erosion surfaces are younger than rocks they cut across
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inclusions
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igneous and sed rocks which contain fragments of other rocks are younger than the fragments
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floral and faunal succession
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fossil animals and plants occur in a definite order and indicate specific intervals of time
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time scale subdivisions
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eons, eras, periods, epochs
based on localities where the rocks were first studied- europe |
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chronological sequence based on-
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superposition
relative antiquity of fossils in the rocks |
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joints
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parallel fractures in rocks occuring commonly as 2-3 sets which intersect.
result from brittle deformation |
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faults
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fractures along which movement has occured.
resulted from brittle deformation |
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normal fault
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hanging wall block moves down
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reverse fault
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hanging wall block moves up
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thrust fault
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a reverse fault inclined 30 degrees or less
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lateral (strike-slip) fault
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horizontal movement (FWB/HWB irrelevant)
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Earthquakes occurence
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within the outer 400 miles of the earth
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West Yellowstone Quake
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1959 major landslide
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Alaskan Earthquake
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1964 tsunami, lasted long 3 minutes
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Mexico City quake
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1985- selective building damage
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mercali scale
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roman numerals, amount of structural damage produced.
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Isoseismal maps
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show areas of equal damage
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Richter scale
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Numbers 1-9, increase by 10 times. amount of energy released
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Geographic Distribution
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along three narrow zones (plate boundaries). In the US- California, alaska, Rockies. In Ohio- West-Central and Northeastern Areas
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Ohio Quakes
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1/3= R3
2/3=Less than R3 1 Mile focus Quake Records began 1960 |
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shockwaves- body waves
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travel through earth.
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Primary P waves
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compressional (like sound waves), travel through any material
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Secondary S waves
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shear (like light waves) travel through solid material only
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Surface L waves
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travel on surface only.
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P waves to S waves
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P waves travel almost twice as fast as S waves
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L waves travel slowest but..
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Largest waves
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Pendulum principle
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3 instruments at each seismic station. Distribution
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Seismograms
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paper records of earthquakes
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Travel-time curves
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P-S arrival; time difference=distance to epicenter
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Determining the Epicenter
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P-S arrival; time difference, but need 3 stations (3 circles)
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Determining the focus
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similar to epicenter determinations, but need 3 spheres
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Determining the magnitude
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max amplitude (height) of S waves P waves
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Seismic Gap theory
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based on past history of quakes along known earthquake-generating faults (San Andreas)
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Dilatency theory
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under stress, rock swells before it ruptures, causing local changes
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Precursor events
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increased number of micro-quakes
changes in water level in wells increased leakage of radon gas in water wells cahnges in earths magnetism and electrical conductivity bizarre animal behavior |
