geol 106 unit 3

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geol 106 unit 3
2011-03-17 23:20:47

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  1. aa flow
    jagged and blocky lava flow
  2. batholith
    large mass of igneous rock formed when magma at depth is crystalized and then exposed
  3. caldera
    collapse depression having circular form
  4. cinder cone
    • aka scoria cone
    • made of dark basaltic lavas and reddish cinders
    • usually only erupts once
  5. columnar joint
    elongated pillarlike columns formed as igneous rock cools and devlops shrink fractures
  6. compostie cone
    • aka stratavolcanoes
    • composed of lava and pyroclastic material
    • highly explosive
  7. conduit/pipe
    linear fissure in volcano allowing magma to move up to opening
  8. continental volcanic arc
    produced when oceanic plate subduct beneath continental plate
  9. crater
    funnel-shaped depression at top of volcano
  10. decompression melting
    lowering of rock melting temp when confining pressure drops
  11. dike
    magma injected into fractures in volcanoes
  12. eruption column
    • bouyant plumes of explosive clouds of ash and gas
    • made from highly viscous and silica rich magma
  13. fissure
    crack in crust
  14. fissure eruption
    eruption of lava extruded from crack in crust
  15. flood basalt
    very fluid lava remaining molten long enough to flow great distances
  16. furmarole
    secondary vents that emit gases
  17. geothermal gradient
    change in temperature with depth
  18. hot spot
    concetration of heat in mantle that produces magma that extrudes to surface
  19. intraplate volcanism
    eruptions at interior of plates
  20. island arc
    volcanism at oceanic convergent plate margin
  21. laccolith
    viscous bulging sill
  22. lahar
    earthflow of volcanic ash
  23. lava tube
    tunnel in hardened lava acting as horizontal conduit for lava flowing from vent
  24. mantle plume
    hotter than normal magma that ascends to surface
  25. nuee ardente
    fiery pyroclastic flow
  26. pahoehoe
    smooth twisting lava flow
  27. parasitic cone
    small volcano formed on side of volcano form side vents
  28. partial melting
    • process of igneous rock melting where mineral melt at different rate
    • usually produces high silica magma
  29. pluton
    magma at depth
  30. pyroclastic flow
    hot gases infused with incandescent ash and rock fragments
  31. sheild volcano
    accumulation of fluid basaltic lava in a broad flat dome shape
  32. sill
    tabular plutons when magma injects between sedimentary layers
  33. vent
    surface opening of volcano
  34. viscosity
    fluid's resistance to flow
  35. volatiles
    • gaseous components of magma
    • especially water
  36. volcanic neck
    isolated, steep-sided erosional remnant consisting of lava that once occupied volcanic vent
  37. accretionary wedge
    accumulation of sed and meta rocksalong subduction zone
  38. active continental margin
    beginning of a subduction zone
  39. anticline
    upfolding rock
  40. basin
    • 3d syncline
    • bed rises from core in every direction
  41. brittle failure (brittle deformation)
    fracture once strength is exceeded
  42. deformation
    change in original shape or size of rock body
  43. dip-slip fault
    movement is parallel to inclination of fault
  44. dome
    • 3d anticline
    • bed dips away from core in every direction
  45. ductile deformation
    solid-state flow that producing changes in rocks without fracturing
  46. fault
    fractures in crust where displacement has taken place
  47. fault-block mouuntains
    mntn formed from displacement of rock along fault
  48. fault scarp
    exposed areas after fault displacement
  49. fold
    wavelike undulation
  50. graben
    central block in between normal faults that subsides as plates move
  51. gravitational collapse
    gradual subsidence of mountains caused by lateral spreading of weak material
  52. horst
    uplifted structure surrounding graben
  53. isostasy
    floating crust in gravitational balance
  54. isostatic adjustment
    establishing of a new graviational equilibrium
  55. joint
    fractures in crust without displacement
  56. monocline
    step-like folds in otherwise horizontal strata
  57. normal fault
    hanging wall moves down
  58. orogenesis
    proccesses that build mountains
  59. passive continental margin
    formation of subdusction zone from same plate
  60. reverse fault
    • hanging wall moves up
    • dips greater than 45deg
  61. strike-slip fault
    displacement horizontal and parallel to fault
  62. syncline
    downward fold
  63. terrane
    any crustal fragment that has distinct geologic history from adjoining rocks
  64. thrust fault
    • hanging wall moves up
    • dip is less that 45deg
  65. transform fault
    strike=slip fault between large crustal plates
  66. angular unconformity
    tilted or folded strata overlain with younger flat-laying strata
  67. conformable
    rock layers deposited without interruption
  68. catastrophism
    belief that landscapes formed from catastrophies
  69. correlation
    matching up rocks of similar age in different regions
  70. princliple of cross-cutting relationships
    fault or intrusion is younger than affected rocks
  71. disconformity
    unconformity where beds abova nad below are parallel
  72. eon
    • greatest division of time in geologic time scale
    • Precambrian, Phanerozic
  73. epoch
    • fourth subunit of geologic time
    • divides periods
  74. era
    • second subdivision of geologic time
    • divides eons
    • especially Paleozoic, Mesozoic, Cenozoic
  75. fossil
    remains or traces of prehistoric life
  76. principle of fossil succession
    • fossil organisms succeed each other in a definate and determinable order
    • time period can be recognized by fossil content
  77. geologic time scale
    • division of Earth history
    • uses relative dating princliples
  78. half-life
    time required for half the parent material to decay into daughter material
  79. inclusions
    • pieces of one rock unit contained within another
    • contained rock is older
  80. index fossil
    geographically widepread fossils limited to a short span of time thats provides a method of mathching similar aged rocks
  81. nonconformity
    break that separates older rock from overalin younger rock
  82. numerical date
    actual number of years that passed since event occured
  83. principle of original horizontality
    • layers ore deposited in horizontal pattern
    • rocks found otherwise were changed since deposition
  84. paleontology
    study of fossils
  85. period
    • third subdivision of geologic time scale
    • divides eras
  86. radioactivity
    spontaneous decay of certain unstable nuclei
  87. radiocarbon dating
    radiometric dating using carbon-14
  88. radimetric dating
    • determining actaul age of rocks that contain radioactive isotopes
    • uses percentage of parent to daughter material based on know half-life
  89. relative dating
    placing rocks in sequence of formation
  90. law of superposition
    each bed is older than the one above it
  91. unconformity
    period where depostion ceased and erosion and/or uplift occured
  92. uniformitarianism
    physical, chemical and biological laws that operate today also occured in the past