Mid-Term 2

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Mid-Term 2
2010-04-01 13:49:23
Geology Woodhead Exam Midterm

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  1. Chemical Weathering
    When minerals react w/ air & water to form new minerals
  2. chemical stability
    measure of a substance tendency to retain its chemical identity rather than reacting spontaneously to become a different chemical
  3. physical weathering
    fractured large rock into smaller pieces which are more easily transported & eroded
  4. strike
    compass direction of a rock as it intersects with a horizontal surface
  5. dip
    measured at right angles to the strike, is the amount of tilting angle at which the bed inclines from the horizontal
  6. geologic maps
    represents the rock formation exposed at earths surface
  7. folding a common form of deformation in?
    layered rocks - rarely stay horizontal
  8. syncline
    downfold into trought
  9. limbs
    2 sides of a fold
  10. basin
    synclinal structure, bowl shaped depression of rock layers that beds dip radially toward central point
  11. dome
    anticlinal structure, broad circular or oval bulge of rock layers
  12. relative humidity
    amount of water vapor in air, relative to saturation of air
  13. rain shadow
    areas of low rainfall on downwind slopes
  14. what are the 3 main types of tetonic force
    tensional, compressive, shearing
  15. tensional
    in brittle crust, produce normal faulting my split apart, causing a rift valley
  16. compressive
    when 2 plates collide, crust can be compressed across a wide zone. fold & thrust belt
  17. shearing
    long transform in faults are rarely straight. faults have bends & jogs -> change tectonic forces. cause secondary faulting & folding
  18. recharge
    infiltration of water into any subsurface formation, often from the surface by rain/melthing snow
  19. what did william smith discover
    fossils can help to order relative ages of sedimentary rock
  20. principle of faunal succession
    layers of sedimentary rocks in outcrop contain fossils in a defininte sequence. the same sequence can be found at other location
  21. ground water
    mass of water stored under earths surface
  22. porosity
    % of rock, soil or sedminets total volume that is taken up by pores
  23. aquifier
    bed that store & transmit groundwater in sufficient quantity to supply wells
  24. unsaturated zone
    level at which the pores contain some air and are not completely filled with water
  25. groundwater table
    boundary between 2 zones
  26. saturated zone
    level at which the pored of the soil or rock are completely filled with water
  27. reservoir
    each place that stores water
  28. hydrologic cycle
    cyclical movement of water from ocean -> atmosphere by evaporation -> surface by rain -> streams by runoff & groundwater -> ocean
  29. droughts
    periods of months/years when precipitation is lower than normal
  30. foliated rock 4 main criteria
    • 1. size of crystals
    • 2. nature of foliation
    • 3. depree that minerals are segregated in color bands
    • 4. metamorphic grade
  31. principle of original horizontality
    sediments are deposited under influence of gravity as nearly horizontal beds. if we find folded/faulted the strata layers were deformed by tectonic forces after sediment deposit
  32. principle of superposition
    each sediment layer of undisturbed sequence is younger than one beneath it & older than one above
  33. suspension
    sediment/rocks suspended in stream
  34. water table
    barrier between saturated & unsaturated water
  35. weathered
    general process that breaks rocks into fragments by combination of physical fracturing & chemical decomposition
  36. subduction
    sinking of oceanic plate under overriding plate at ca convergent plate boundary. overriding plate maybe oceanic or continental
  37. rock rall
    very rapid movement in which newly detached individual block of rock plummet suddenly in free fall from a cliff or steep mountain side
  38. saltation
    an intermittent jumping motion or sand or fine sediment alon a steam bed in which grain are suck up into the flow by turbulent eddies move with the current for a short distance & then fall back to the bottom
  39. plunge
    a fold whose axis is not horizontal but dip
  40. grading
    fine particles settle to bottom & heavy at top. occurs in slow moving water
  41. inverse grading
    heavy particles at bottom & small at top. occurs in fast moving bodies of water
  42. longshore current
    a current that flows parallel to the shoreline, the summed longshore components of water motion of waves that break. obliquely with respect to the shore
  43. bedding
    formation of parallel layer of sediment as particles settle to the bottom of the sea, a river or a land surface
  44. perched
    the groundwater table in a shallow upper surface of an aquifier that is perched above & separated from the main body of groundwater by aquilude
  45. plastic
    total of all the small movement of the ice crystals that make up a glacier, resulting in a large movement of ice
  46. half-life
    time required for half of the original number of radioactive atoms in an element to decay
  47. weathering
    one of major geological processes in rock cycle, shapes earths surface/alters rock materials, converting all kinds of rock into sediment -> soil
  48. 4 key factos that control rock fragmentation & decay
    • 1. properties of parent rock
    • 2. climate
    • 3. presence/absence of soil
    • 4. length of time rocks are exposed to atmosphere
  49. mass wasting
    all the processes by which masses of rock & soil move downhill under the influence of gravity
  50. erosion
    set of processes that loosen soil & rock & move them downhill/strem where they are depisted as sedimentary layers.
  51. what 4 precipitations cause decay & breakdown
    rain, wind, ice & snow
  52. what are the processes that loosen & transport soil/rock down?
    erosion & mass wasting
  53. outcrop
    basic source of deformation information where bedrock that underlies surface is exposed
  54. what is an important clue to overall structure of outsrop
    orientation of layers
  55. what described the orientation of a rock layer exposed at an outcrop
    strike & dip
  56. what are the 4 types of metamorphism
    regional, contact, seafloor, shock
  57. regional metamorphism
    caused by high pressures & temperatures that extend over large regions
  58. contact metamorphism
    changes in minerology & texture of rock resulting from the heat & pressure in small area
  59. seafloor metamorphism
    associated with mid ocean ridges in which changes in chemical composition produced by fluid transport
  60. shock metamorphism
    occurs when minerals are subject to high pressure & temperature of shock waves when meteor collides with earth
  61. metamorphism p-t
    history of changes in conditions of pressure & temperature
  62. what are 3 principal factors of metamorphism
    • 1. internal heat of earth
    • 2. pressure
    • 3. fluid composition
  63. push rocks at earths surface down to great depths subjecting them to high pressure & temperature
  64. role of temperature in metamorphism
    heat effects chemical composition, minerology, & texture.
  65. geothermal gradient
    increase of temperature with increasing depth
  66. role of pressure in metamorphism
    confining & directed
  67. confining pressure
    general force applied equally in all directions
  68. directed pressure
    force exerted in a part direction pressure, like temp increases with depth
  69. role of fluids in metamorphism
  70. metasomatism
    change in a rocks bulk chemical composition by fluid transport of chemical components into or out of rock
  71. Reverse thrust fault
  72. Plunging fold
  73. Left lateral strike slip
  74. Horizontal fold
  75. Normal Faulting
  76. overturned folds
  77. oblique slip fault
  78. asymmetrical folds
  79. tensional tectonics
    normal faults w/ hih dip angles in upper crust, flatten w/ depth
  80. compressive tectonics
    compression on continental crust on thrust faults with low dip angle
  81. shearing tectonics
    shearing continental crust on nearly vertical strike-slip fault
  82. plunging anticline, plunging syncline
  83. right lateral strike slip
  84. symmetrical folds