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138 Cards in this Set
- Front
- Back
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absolute age dating
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based on relationships between rock units
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carbon dating
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uses carbon and looks at half life in order find the age of a rock
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What is the most accurate type of geologic age dating?
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carbon dating
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angular unconformity
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layered rocks were uplifted
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noncomformity
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Metamorphic rocks were overlaid by sediments
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disconformity
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gap in fossil record or irregular erosion
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where do divergent plate boundaries usually occur?
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oceanic ridges
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where do convergent plate bounaries usually occur?
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deep ocean trenches
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normal fault
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hanging wall block moves down relative to foot wall block
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thrust fault
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hanging wall block moves up relative to foot wall block
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strike slip
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displacement is horizontal and parallel to the strike
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transform fault
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strike slip fault that cuts through the lithosphere
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fault
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-fracture in the crust where displacement has occurred
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What is the cause of earthquakes?
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-rapid release of energy by atomic explosions or volcanic eruptions
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factors in Earthquake damage
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-magnitude
-proximity to epicenter -ground substrate -population density -nature of building construction -building resonance |
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what causes Earthquake damage?
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-landslides
-fires -rupture of roads -tsunamis -building/bridge collapse |
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Intensity
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-measure of degree of earthquake shaken at a given locale based on amount of damage
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magnitude
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estimate of total amount of energy released during an earthquake, based on seimic records
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epicenter
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-location on the surface directly above focus
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focus
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-source of earthquake, or hypocenter
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seismic P waves
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-primary waves (push-pull)
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Seismic S waves
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secondary waves (shake, change shape)
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Seismograph
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-records seismic waves
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Why are abyssal planes flat?
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-they are flat because of thick accumulations of sediment that have buried an otherwise rugge ocean floor
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Turbidite
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-turbidity current deposit characterized by graded bedding
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atoll
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-coral island consisting of nearly continuous ring of coral reef surrounding a central lagoon
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marine snow
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-a continous shower of mostly organic detritus fallng from upper layer of the water column
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Ophiolite sequence
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deep sea floor spreading
pillow basalts sheeted dike gabbro layered gabbro peridotite |
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How do pillow basalts form?
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-basaltic lava solidifies in an underwater environment and developes a structure that is like a pile of pillows
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what are some processes of mass wasting?
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-rockfall
-landslide -rock avalanche -slump -earthflow -mudflow -surface creep -solifluction |
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liquification
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-transformation of a stable soil into a fluid that is often unable to support buildings or other structures
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solifluction
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-slow, downslope flow of water saturated materials
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Name the different ways that streams transport things
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-suspension
-dissolution -bedload |
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Why does bedload size decrease downstream
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-particles that are too large or too heavy to move by saltation slide to the bottom
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Where is flow velocity the greatest?
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-at the thalweg
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Floodplain
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-low, flat portion of a stream valley subject to periodic inundation
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point bar
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-crescent shaped accumulation of sand and gravel deposited on inside of a meander
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cut bar
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-on the outside of a meander
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levee
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-restricts water flow into a river
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oxbow lake
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-curved lake produced when a stream cuts off a meander
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stream capacity
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-total amount of sediment a stream can carry
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stream competence
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-maximum size of sediment a stream can carry
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discharge
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-total amount of water flowing past a certain point
width X depth X velocity |
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base level
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level below which a stream cannot erode
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stream problems related to urban development
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-excessive sediment runoff
-road runoff -trash, garbage -lawn chemicals -pathogens -agricultural runoff -stream pollution |
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Ways to limit flooding
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-better flood management
-space for natural wetlands -land use planning -building restrictions |
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How often do streams flood?
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-about once every two and a half years
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groundwater
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water from the ground
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aquifer
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-geologic unit from which you can withdraw water
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aquitard
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-unit through which water does not tend to flow
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water table
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-surface that slopes
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perched water table
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-localized zone of saturation above the water table
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spring
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-result of a natural outflow of groundwater
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hydraulic gradient
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-water table slope
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porosity
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-amount of porous space
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permeability
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-ease with which fluids can move through
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Problems with withdrawing water too fast
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-depletion of major freshwater resources
-salt water intrusion -ground subsidence -ground collapse |
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glacier
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-river of ice, formed by snow that changes into ice
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what would be a result of our glaciers melting?
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-people would lose a source of clean, freshwater
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rock flour
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pulverized rock produced by the grinding effect of a glacier
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the origin of U shaped valleys
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-glacial valleys
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the origin of aretes
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-two glaciers flowing past each other
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the origin of horns
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-formed by glcial action
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the origin of recessional moraines
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-formed as the ice front stagnates during glacial retreat
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origin of lateral moraines
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-when debris falls to the glacier from valley walls
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origin of kettle lakes
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-when ice melts and a bowl shaped depression is left
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esker
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-when sand/gravel is deposited by a stream flowing in a tunnel beneath a glacier
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Types of deserts
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-arctic
-alpine low latitude deserts -middle latitude deserts -rainshadow |
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What makes it a desert?
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-dry
-extreme temperatures |
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-Xerophytes
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-trees that don't grow because of absence of snow
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Geologic processes in deserts
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-mass wasting
-chemical weathering -physical weathering -water -wind |
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ventifact
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-a cobble or pebble polished and shaped by sandblasting effect of the wind
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alluvial fan
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-a fan shaped deposit of sediment formed when a stream slope is abruptly reduced
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bajada
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-apron of sediment along a mountain front created by the coalesence in a stream channel
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playa lake
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-temporary lake in a playa
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desertification
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-when arid lands are turned into deserts
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causes of desertification
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-overgrazing
-overpopulation |
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-Some desertification areas
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-Afria
-Middle East -U.S.A. |
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beach drift
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-transport of sediment in a zigzag pattern along a beach, caused by uprush of water
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What is the main factor that controls tides?
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-the moon
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Spring Tide
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-when the Earth-Moon-Sun- system is aligned
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Neap Tide
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-when the forces of the moon and sun act on Earth at right angles
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Seawalls
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-build parallel to the shoreline, designed to armor the coast and defend property from waves
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Jetties
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-confine the flow of water, narrow it
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Groins
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-barrier built at a right angle, traps sand moving parallel to the shore
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Advantages and disadvantages of beach nourishment
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advantages: improves storm protection, doesn't require hard stabalization, beach quality is improved
disadvantages: not permanent, replacement sand will eventually be removed, very expensive, unwanted environmental effects |
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shoreline erosion
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east coast- tectonically quiet, narrowing of beaches, flow to coast is interrupted by dams, development is a problem
west coast-storms strike coast, erode dunes, carry sand from beaches |
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Name the layers of the Earth, from inside to outside
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1.core
2.mesophere 3.mantle 4. crust |
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Compare continental and oceanic crust
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- continental crust is older
- continental is made of granite, oceanic of basalt - continentel has a higher elevation -contintental crust is thicker |
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Describe Earth's crust
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- it is the thin, rocky, outer layer
-it is divided into oceanic and continental crust |
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What is a mineral?
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-a naturally occuring, inorganic solid, with a specific composition and definite internal arragement of atoms
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How do minerals form?
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-evaporating from a solution
-solidifying from a cooling melt -alteration by weathering process -alteration within the Earth's surface |
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Name some common minerals
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-orthoclase, plagioclase, augite, hornblend
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Igneous rocks
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-rocks that form from solidifying from a cooling melt
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exrusive
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on the earth's surface
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intrusive
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in the Earth
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Name the different types of Igneous rocks and give an example for each
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Felsic- granite
Mafic- diorite intermediate- gabbro |
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Metamorphic Rocks
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-alteration of pre-existing rocks in a solid state through application of heat and pressure
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Examples of metamorhpic rocks
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slate, quartzite, schist
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Sedimentary rocks
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-deposition of weathered materials of other rocks
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Examples of Sedimentary rocks
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chalk, limestone, sandstone, clay, shale
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Divergent plate boundaries
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-two plates move apart (mid atlantic ridge)
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Convergent plate boundaries
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-two plates moving together (peru-chili trench)
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Transform boundaries
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-two plates grinding past each other (San Andreas Fault)
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Name the Geologic Eons
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-Archean
-Protozoic -Phanerozoic |
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What age are we living in today?
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Post Cambrian
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What is the approxomite age of the Earth?
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4.6 billion years old
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Compare the ages of the Oceanic and Continental crust and explain why they are this way
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age of Oceanic Crust: 180 million years old
age of contintental crust: 4.4 billion years old reason: sea floor spreading, new lithosphere is constantly being made and the old is beign destroyed |
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Name the three types of Volcancos
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shield- mafic (Hawaii)
Strato- intermediate (Mt. St. Helens) Cinder- Felsic (Arizona) |
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Weathering
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-disintegration of rock at the Earth's surface by physical or chemical processes
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Types of physical weathering
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-frost wedging
-thermal expansion -pressure release jointing |
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Types of Chemical weathering
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-dissolution
-oxidation -hydrolosis |
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Mudcracks
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-mud squeezes in on the rock and shrinks it laterally
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graded bedding
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-when it goes from coarse to fine grains
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wave ripple marks
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-symetrical
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current ripple marks
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-asymetrical
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cross beds
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-tell you the current direction, wind blown deposition
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bedding
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-layering of sediment
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dunes
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-a hill of sand
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What type of landscape is coal found in?
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warm, tropical
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what type of landscape is limestone found in?
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marine
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What is the wisconsin state fossil?
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Trilobite
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Fold
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state of falt and planar surfaces, bent or curved by deformation
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Brittle
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rock breaks
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Ductile
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rock doesn't break
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tension
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normal fault
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compression
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reverse fault
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shear
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ductile deformation
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strike
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horizontal line on a planar surface
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dip
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goes down, at a right angle to the strike
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syncline
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oldest strata on the outside
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anticline
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oldest strata on the inside
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dome
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rocks that might have been flatlined get pushed back
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double plunging
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plunges in two directions
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mass wasting
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downslope of Earth's materials due to gravity
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Motions of mass wasting
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falling, flowing, sliding
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Factors in Mass wasting
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-rainfall
-construction -undercutting by waves -angle of repose -material of ground |
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What types of mass wasting produce the most damage?
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surface creep and solifluction
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