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Exam 3
1121
80
Geology
04/28/2009

Additional Geology Flashcards

 


 

Cards

Term
cause of most waves
Definition
*WIND
-strong wind and long "fetch" have larger waves
Term
wave motion
Definition
study this from book
Term
longshore current/transport
Definition
study picture
Term
cause of tides
Definition
gravitation interaction among Earth, moon, sun and oceans
Term
spring tide
Definition
sun, moon, and earth line up
-higher high tides and lower low tides
Term
neap tide
Definition
sun,earth, and moon form right angle (moon is above the earth)
-lower high tides, higher low tides
Term
storms
Definition
*magnify effects of tides, waves, etc
*normal part of beach evolution
Term
beach erosion
Definition
*formation of a beach
*a natural beach is not destroyed by "beach erosion"
*Beach is lost only when structures are employed to lock the shoreline in place
Term
formation of a beach
Definition
*action of waves on shoreline- removal of all but coarsest sediment (SAND)
*as shoreline moves, beach moves with it
Term
causes of shoreline retreat
Definition
*global sea-level rise
*land subsidence
*sand starvation
Term
global sea level rise
Definition
*present rate: 2mm per year and four feet of lateral shoreline movement
*10-25 cm over a century
Term
land subsidence
Definition
*examples- east texas and lousiana
*Louisiana losing 25 mi^2 of land per year
Term
beach retreat solutions
Definition
*hard stabalization
*soft stabalization
*move out of the way
Term
hard stabalization
Definition
*build hard, immovable structure to anchor beach
*structures are seawall and groin/jetty
Term
soft stabalization (beach replenishment)
Definition
*add sand to beach
*advantages-save beach and buildings
*disadvantages-expensive and has a short lifespan
Term
crystal formation
Definition
*stress
*strain
*britle deformation
*ductile deformation
*fault
*joint
*strike and dip
*dip
*strike
Term
stress
Definition
applied force to rocks
Term
strain
Definition
response of rock to stress
Term
brittle deformation
Definition
breakable, faulting (rock breaks)
Term
ductile deformation
Definition
folding (rock bends)
Term
fault
Definition
a break in a rock along movement
Term
joint
Definition
a break in a rock along NO movement
Term
strike and dip
Definition
describes the orientation of a planier feature (could be tilted, folded rock layers)
Term
dip
Definition
tells you the downward tilt of a feature; measured as an angle below horizontal
Term
strike
Definition
compass direction of the intersection of a tilted plane with the horizontal
Term
ductile deformation again
Definition
*(folds)
*anticline- "A" up rock layers
*synticline- "U" shaped rock layers
*folds result from compression/shortening
Term
brittle deformation again
Definition
*(faulting)
*dip/slip faults-motion parallel to the dip direction, has both vertical and horizontal movement
Term
causes of earthquakes
Definition
*volcanic eruptions
*nuclear weapons testing
*elastic rebound
Term
elastic rebound
Definition
*rocks bend elastically as stress applied
*faulting releases elastic strain instantly
*earthquake waves radiate out from fault break
*aftershocks as fault strain fully dissipater
Term
magnitude and intensity- scale (1902)
Definition
*subjective
*based on eyewitnesses accounts, damage
1-barely felt
6-felt by all, slight damage
12-total destruction
Term
richter magnitude scale
Definition
m=log10(X/T)+lamda
*m-magnitude
*X-amplitude of ground motion
*T-period of ground motion
*lamda-distance correction function
*m=6-7:serious
*m=7-8:major
*m=8-9:massive
Term
moment magnitude scale
Definition
*similar to richter scale
*more accurate and consistent
*based on: physical prop of affected rock, surface area of fault rupture, amount of fault slip
Term
epicenter
Definition
*point of earth's surface is vertically straight above the focus(earthquake)
Term
focus
Definition
Term
seismograph
Definition
weight that shows motion of disturbance within the earth
Term
seismogram
Definition
Term
p waves
Definition
Term
s waves
Definition
*secondary waves
*shear waves
*motion within wave is perpindicular to direction of travel
*travel through solid only
Term
surface waves
Definition
*analogues to waves on water surface
*propogate along free surface
*circular ground motion (groud-roll)
Term
earthquake prediction
Definition
*almost impossible to make precise predictions
*uncertainties of decades to centuries
*earthquake precursors
*"seismic gap" method
Term
seismic gap
Definition
Term
earthquake precursors
Definition
*tilting or swelling of ground
*groundwater pressure change
*electromagnetic field changes
*animal behavior
Term
largest earthquake
Definition
*New Madrid, Missouri
Term
seismograph
Definition
paper with pen that shows the disturbance of the earthquake
Term
damage control of earthquakes
Definition
*build flexible structures, anchor structures to bedrock
*no heavy roofs
*problems with soft sediments
*Loma Prieta-earthquake
*no heavy roofs
Term
problems with soft sediments
Definition
*liquification-(anchorage,ak) sed. liquifies
*amplification (oakland, ca) sed is weaker, movement (Loma Prieta)
Term
Tsunamis
Definition
*(tidal waves)
*off shore earthquakes create waves in the sea
*waves propogate out of the epicenter
*can be huge when hit land
Term
crust/mantle boundary
Definition
*abrupt jump to high velocity material several km deep
*deeper earthquake waves travel faster than shallow
*we can infer that the crust is underlain by denser mantle
Term
Mohoravicic discont
Definition
Term
earth's magnetic field
Definition
*earth behaves like a giant magnet
*earths interior too hot to contain magnetic minerals
*field most likely generated by rotation of solid inner core within liquid core
Term
geomagnetic reversals
Definition
*polarity of earths magnetic field spontaneously reverses
*intervals of a few 10000 years to millions of year (avg-250000yrs)
*last reversal=780000 years ago
*reversals recorded in minerals that act as natural compasses, esp iron rich igneous minerals
Term
plate tectonics history
Definition
*1908-1912: alfred wegener-proposed hypothesis of cont drift
*1950s-1960s=mapping of ocean floor, leads to theory of plate tectonics
Term
hypothesis
Definition
*cont drift- all of the continuity fit together like a jigsaw puzzle;
Term
evidence of plate tectonics
Definition
*distribution of fossils
*paleo climate info=ancient climate
*united glaciacion=combine all continents into antarctica
Term
important steps to theory
Definition
*look at sea floor
*poor resolution of earthquakes
*evidence of sea floor (structure, age, magnetic)
Term
earthquakes
Definition
*polar wandering, heat flow, realtime
Term
seafloor structure
Definition
*mid ocean ridge (block faulting) normal fault-ridge being pulled apart
*large mtn chain
*intense volcanic activity
*seafloor spreading @ ridge= crustal expansion apart
Term
seafloor age
Definition
*not older than 180 million years
*covered by sed. layers
*youngest sea floor coincides with mid ocean ridge
Term
plate tectonics part II
Definition
*theory of plate tectonics- earths lithosphere divided into discrete plates that are in motion relative to each other
*interactions between plates are the main cause of volcanism, earthquakes, mtn bldg and other geo phenom
*plate motion is driven by thermal convection in the mantle
Term
divergent
Definition
plates pull apart, gap filled with lava, build new ocean crust
Term
locations of divergent boundaries
Definition
*midocean ridges (most)
*cont drift (a few) -ocean floor=basalt
Term
rift valley
Definition
located in the eastern part of africa
*linear drift-red sea and gulf of aden
Term
convergent boundaries
Definition
*plates ram together, subduction zone, ocean trench, volcanoes, ocean crust destroyed
Term
types of convergent boundaries
Definition
*oceanic/cont and oceanic/oceanic, cont collision. west side of pacific is oceanic convergent, east side= cont drift, himalaya=cont collision
Term
transform boundaries
Definition
*(san andres fault, ca)
*plates slide horizontal
*links segments of divided boundaries, earthquake hazards
Term
mountains
Definition
*earth is dynamic, constant crustal motion, and crustal deformation, thermal uplift (fault)
Term
why are mtns tall?
Definition
*isostacy- earths crust floats on top of mantle, lighter cont. crust floats higher, thicker cont. crust floats higher
*thermal effects- hot mantle may up crust, important at mid ocean
Term
global warming
Definition
assertion of earths lower atmosphere and oceans have warmed during past
Term
metereological phenomenon
Definition
*climatical evidence clearly tells us the earth is warmer now than it was 10 years ago, 50 years ago, 100 yrs ago, or 10000 yrs ago
*causes of climate change poorly understood
Term
political issue
Definition
*some argue that the earth is warmer bc of human activities and that therefore we need to change our ways
*others argue- the earth isnt warmer, observed warming is natural
Term
earths climate
Definition
*complex balance of forces
*atmospheric- circulation patterns, greenhouse gasses
*oceanic-circular patterns, greenhouse gas source/sink
*geological-position of continents, volcanic gasses/dust
*astronomical (orbital)
Term
climate
Definition
*as atmospheric, oceanic, geological, and astronomical change, earth's climate changes
*earths climate has changed dramatically during the very recent geologic past
Term
greenhouse effect
Definition
entrapment of heat by certain atmospheric gasses(greenhouse gasses)
Term
greenhouse gasses
Definition
*glasses that are transparent to sunlight but trap heat (infra-red) energy (H2o,CO2,CH4,others)
Term
how greenhouse works
Definition
*sunlight (light energy)-passes through atmosphere,absorbed by ground, ground warms up
*heat energy from ground radiated back into atmospheric
*heat absorbed by greenhouse gasses
*atmosphere warms up
Term
pros of greenhouse
Definition
*normal part of earths climate
*keeps eart 60 degrees
*without= 15 degrees
Term
measuring past temps
Definition
*ice cores
*tree rings
*lake and ocean sediment
*cave sediment
Term
ice cores
Definition
*greenland and antarctica
*trapped atmospheric gasses
*snow depth
*dust, contamination
Term
the ice ages
Definition
Pleistocene era (1.65 my-10K yrs ago)
*numerous advances and retreats of continental glaciers in northern hemisphere
Term
most important of measuring past temps
Definition
*ice cores
*ocean sediment