Geology 240 – Flashcards
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mendel
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father of modern genetics
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padagrim shift
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base of science shifts
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plate techtonics revolution
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1960
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90 % of earthquake energy is released around
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rim of pacific
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bathymetry
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ocean topography
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how deep is the mariana trench
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9 km
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earthquake belt
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defines the edge of techtonic plate
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lithosphere
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100 km thick, rigid, what plates are made of,
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asthenosphere
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weak, under lithosphere
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almost all mountain building occurs
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at the boundaries of plates
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tectos
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builder greek
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Divergent boundary
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-plates move away from each other -new lithosphere is created -creates new land -basalt -massive sulfide deposits -decompression melting -
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mid-atlantic ridge
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-10-100 km long -100km thick
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red sea
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baby ocean, divergent boundary
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iceland
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divergent boundary
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basalt
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non exploding, shield volcanoes
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olduvai gorge
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divergent boundary
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rifts
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split 120 degrees, 2 of 3 go and one fails
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aulochogene
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failed rift arm, Mississippi river
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Missouri 1812
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earthquake not on boundary
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wadati-benioff zone
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700km deep, subduction zone
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Average elevation of continents
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1km
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Average depth of ocean
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5km
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Isostasy
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relative buoyancy
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Oceanic crust
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more dense, Mg Fe
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Continental crust
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less dense, Si Al
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Volcanos
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above slab that is 100km below on subduction zone
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Stick slip earthquake
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-gradual bending of rock -99% of time dont slip -cause the most damage
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2km per second
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4473 mph
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3km per second
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6710 mph
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4km per second
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8947 mph
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subduction megathrust
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20-30km deep under subduction zone
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island arc
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ocean-ocean subduction zone volcano
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continental arc
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-ocean-continent subduction zone volcano -most dangerous volcanos - andesite is viscous and full of silica - gas expansion=explosion -nuee ardante
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Transform boundary
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-connect spreading ridge segments -strike slip faults -shear stress
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hot spots
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-flood basalt from core mantle -louigi next hawaiian island -yellowstone
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wilson cycle
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two continental plates consuming an ocean
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iceland
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hot spot and oceanic spreading ridge
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average crust thickness
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30km
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Isostatic rebound
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mountain becomes smaller, crust becomes thinner, greenland
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Alfred Wegener
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-compiled data for continental movement -supercontinent pangea -superocean panthalassa -DuTo agreed
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Laurasia
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Northern continents
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gondwanaland
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southern continents
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latitude
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north/south, equator
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longitude
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east west, prime meridian
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Inclination
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-the angle between the magnetic field vector and surface of the earth -tells us latitude when rock formed
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Declination
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-the angle between the horizontal component of the magnetic field vector and geographic north -tells us where paleo-pole was
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currie point
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-600 degrees C
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The earths magnetic field has been pointing towards north pole for how many years?
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700,000
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oldest oceanic lithosphere is how many years old?
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200,000,000 west pacific marionis trench
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oldest rock?
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3.8 billion years old
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how fast is east pacific rise spreading?
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5x faster than mid atlantic ridge
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spreading ridge
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-slow -axial valley
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spreading rise
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-faster -rounder
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How long ago did N. and S. America split?
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110million years
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Oldest mineral
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4.2 billion years old
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Carbonaceous Chondrite meteorite
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-4.6 billion years old -cool -from beginning of solar system
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U238 1/2 life
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4.49 billion years
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K40 1/2 life
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1.19x10^10 years
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C14 1/2 life
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5,570 years, radiocarbon
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Fault
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crack in the rock with relative motion to the blocks on either side
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speed of slip needed to generate earthquake
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3km/second
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scarp
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escarpment, cliff feature due to fault
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Isotropic stress
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stress pushing inward in same direction, (scuba diving)
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tectonic stress
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location specific, not same in all directions
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normal stress
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holds faults together
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shear stress
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causes slippage
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as you go down into the earth temperature increases at what rate?
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30degres C per km
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hypocenter/ focus
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point on fault that slips first, 3D
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epicenter
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point on surface above hypocenter
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hanging wall
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moves down on normal fault, moves up on revers fault
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normal fault
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-divergent boundary -extension of crust
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reverse fault
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most mountains in world are hanging wall uplifts on reverse fault
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Transform fault
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strike slip, vertical, san andreas
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Juan de fuca plate
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-subducted into cascadia -makes cascade mt range
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lahar
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volcanic mudflow, deadly
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lidar
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laser terrain mapping
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basin and range province
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-western north america -horst (high) -graben (low)