GEOS - 5. Sedimentary Rocks

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GEOS - 5. Sedimentary Rocks
2015-02-18 20:06:52
geology sedimentary

For Exam 1
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  1. Sedimentary rocks make up less than ___ percent of the crust.
  2. Sedimentary rocks cover ___ percent of the continents.
  3. Where are sedimentary rocks made?
    On the surface of the earth
  4. How is a sedimentary rock formed?
    Sediment buried & squeezed
  5. Define weathering.
    Breaking apart rock, mechanically and chemically.
  6. Define erosion
    The moving rock parts somewhere else
  7. List mechanical erosion methods
    Water, wind, gravity (landslides), ice
  8. Define clast.
    A chunk of rock; clay, sand, gravel
  9. Define chemical erosion.
    occurs when water transports dissolved minerals away from their source rocks (example: acidic rainwater dissolves limestone & it ends up in caves)
  10. Define mechanical deposition
    Slide stops, wind/water slows, ice melts
  11. What is compaction?
    Sediment compacted into a denser state,reduction in void space btn particles
  12. Define cementation:
    Chemical precipitation in pores; filling of void spaces by chemical precipitation
  13. What is porosity?
    Measure of relative amount of void space
  14. Besides compaction and cementation, what can also contribute to the lithification of rock?
    Crystallization; crystal growth w/in the void spaces in a rock
  15. Define clastic sedimentary rock.
    Sediments --> rock
  16. What are the types of sediments ordered from small to large?
    Clay, sand, gravel
  17. What is the most common mineral in sand?
  18. What depositional environments will you get poorly sorted clastic sediments?
    landslade, glacier, slow streams
  19. What depositional environments will you get well sorted clastic sediment?
    Slow streams & wind, beach (waves)
  20. What sediment makes conglomerate?
    rounded gravel particles, sediments of high-velocity streams
  21. Describe breccia.
    Like conglomerate except w/ angular particles
  22. Describe sandstone.
    • Made of sand, quartz
    • 10% of sedimentary rocks
    • strong, hard to eroid
    • cemented together
  23. Describe shale.
    • Made of clay
    • 2/3 of all sedimentary rocks are shale
    • splits into thin slabs (fissile)
    • weak, easy to erode
  24. What is oomicrite?
    rock containing abundant oolites w/in a muddy matrix
  25. How is a chemical sedimentary rock created?
    Chemical transport of rock particles - dissolved in water, deposit chemically
  26. How is limestone formed?
    Biochemical, from shells on seafloor (calcite), dissolved over 100s-10,000 of years
  27. Describe limestone
    • strong, easy to erode because it is water soluble
    • changes through time rapidly on a geological scale
  28. What percentage of sedimentary rocks is limestone?
  29. What are other important chemical sedimentary rocks?
    Chert, quartz
  30. How is iron ore formed?
    Water with dissolved iron but cannot be oxidated
  31. Name two evaporites.
    gypsum, salts
  32. Describe the strength of an evaporite.
    Extremely weak, behaves as plastic material under pressure.
  33. What is bedding?
    Sediment laid down in layers/beds/strata
  34. What is stratigraphy?
    Study of layers and what has happened at a particular time; the branch of geology that deals w/ the horizontal and vertical changes and relationships between sedimentary rock units
  35. What is uniformitarianism?
    The processes used to understand rocks and rocks used to understand processes
  36. What is a fossil?
    Remains of life (footprints, burrows, feces, etc.)
  37. What are facies?
    Depositional environments that are divided into subenvironments
  38. What sedimentary rocks are most likely to form on a steep slope?
    Clastic, bad sorting, many types of rock, conglomerate
  39. What sedimentary rocks are most likely to form on a glacier?
    Clastic, bad sorting, contains large particles, conglomerate
  40. What sedimentary rocks are most likely to be formed at a desert by wind?
    clastic, well-sorted, sand --> sandstone
  41. What sedimentary rocks are most likely to be formed at a desert by evaporatoin?
    Chemical-evaporation of water, salt, phosphates, & gypsum
  42. What sedimentary rocks are most likely to be formed by wind-blow dusty soils?
    caused by drought and bad agricultural practices, clastic, very good sorting, shale
  43. What sedimentary rocks are most likely to be formed in a fast-moving river?
    bad sort, boulders & gravel.
  44. What sedimentary rocks are most likely to be formed in a slow-moving river?
    Clay & sand, good sorting
  45. What sedimentary rocks are most likely to be formed at the mouth of a river?
    sand & clay, really good sorting
  46. What is a delta?
    When the river hits the sea
  47. What sedimentary rocks are most likely to be formed at a lake?
    really fine-grained sediments deposited on lake bed, good sorting
  48. What sedimentary rocks are most likely to be formed in a swamp?
    sediment made out of plants --> coal (dead stuff that never gets biodegraded)
  49. What sedimentary rocks are most likely to be formed on a coast?
    Waves --> very well sorted; sand & pebbles from river mouths or weather/erosion
  50. What sedimentary rocks are most likely to be formed at a coral reef?
  51. What sedimentary rocks are most likely to be formed in the deep ocean?
    mix of stuff to make chert, oil, and limestone
  52. What are Appalachian Valley & Ridge ridges made of?
    shale, sandstone, limestone; ridge top: sandstone
  53. What are Appalachian Valley & Ridge valleys made of?
    shales and limestone
  54. What sedimentary rocks are mined for construction?
    gravel, sand, brick, cement, limestone, sandstone
  55. What chemicals serve as resources?
    lime, salts, fertilizer, gypsum (plaster), iron ore
  56. lime is an important ___.
  57. What percent of energy comes from fossil fuels?
  58. Most groundwater usage is from ___.
    Sediment & sedimentary rock
  59. What is the porosity and permeability of shale?
    low porosity, low permeability.
  60. What is the porosity and permeability of sandstone?
    high porosity, high permeability
  61. What is the porosity and permeability of limestone?
    irregular porosity, highly irregular limestone; water flows fast through caves and cracks.
  62. Is clay fertile?
  63. Is clay permeable?
    Not very.
  64. Is sand fertile?
  65. Is sand permeable?
  66. What does detrital origin mean?
    when fragments have been eroded, transported, and deposited.
  67. What does nonclastic mean?
    grains form an interlocking network similar to igneous rocks w/ crystalline texture.
  68. What is parallel bedding produced by?
    Transport of sediment by currents or by deposition in standing bodies of water where sediment particles fall through a column of water to their resting points on the bottom.
  69. What is cross bedding?
    Result of deposition of sediment that moved in wavelike bedforms near sediment-fluid interface