Details Title: Exam 3 Description: 1121 Total Flash Cards: 80 Created: 04/28/2009 09:49:27		New Users: To study from this flashcard set, or to create your own your own study flash cards, REGISTER HERE. Existing Users: CLICK HERE. Additional Geology Flashcards
Cards in this set: 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