Ch 10 Rocks

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My notes for my 8th grade earth science class

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Ch 10 Rocks

  1. 1. The Rock Cycle Ch 10
  2. 2. Rocks and the Rock Cycle <ul><li>Magma is the parent of all rocks </li></ul><ul><li>Three Major types </li></ul><ul><ul><li>Igneous “from fire” </li></ul></ul><ul><ul><li>Sedimentary </li></ul></ul><ul><ul><li>Metamorphic “Changed Form” </li></ul></ul>
  3. 3. <ul><ul><li>The Rock Cycle </li></ul></ul><ul><ul><li>Series of processes in which rock changes from one type to another and back again. </li></ul></ul>
  4. 6. <ul><li>Igneous Rocks </li></ul><ul><li>Forms as Magma cools </li></ul>
  5. 7. <ul><li> - Igneous Rock Structures </li></ul><ul><li>Below crust is Intrusive </li></ul><ul><li>Intrusions- underground rock masses </li></ul><ul><li>Batholiths over 100 square kilometers </li></ul>
  6. 8. <ul><li>Stock under 100 Km 2 </li></ul><ul><li>Laccolith -domed lake of rock, forces up small mountain ranges </li></ul>
  7. 9. <ul><li>Sill layer of rock formed between other layers </li></ul><ul><li>Dikes - magma forcing it self across layers </li></ul>
  8. 10. <ul><li>Extrusions </li></ul><ul><li>Above Crust is Extrusive </li></ul><ul><li>Volcanic neck -lava remains from interior of volcano </li></ul><ul><li>Lava plateau -lava flows out of cracks and covers land </li></ul>
  9. 12. <ul><li>Texture of igneous rock </li></ul><ul><ul><li>Slow cooling allows large (course) crystals to form </li></ul></ul><ul><ul><li>Extrusive rock will have very small crystals </li></ul></ul>
  10. 13. Porphyry Porphyry is a mix of large and small crystals
  11. 14. <ul><li>Rapid cooling may result in a glassy appearance obsidian, or may trap gas bubbles, pumice </li></ul>
  12. 15. Obsidian
  13. 16. Three Families of Igneous Rock <ul><li>Granite light colored or felsic (silica) orthoclase feldspar, quartz, hornblende, and mica </li></ul>
  14. 17. Granite
  15. 18. <ul><li>Diorite medium colored, plagioclase feldspar, hornblende, augite and biotite. Little quartz </li></ul>
  16. 20. <ul><ul><li>Basalt dark or mafic (Iron) plagioclase feldspar, and augite </li></ul></ul>
  17. 21. Basalt
  18. 22. <ul><li>Sedimentary Rocks </li></ul><ul><li>Sedimentary rocks are formed when sediments undergo compaction (pressure) and cementation (glue) </li></ul>
  19. 23. <ul><li>3 types </li></ul><ul><li>Clastic, Chemical, Organic </li></ul><ul><li>Clastic - sediments (small pieces) are carried away by wind, water or ice and left as deposits </li></ul><ul><li>These deposits then undergo cementation and compaction </li></ul>
  20. 24. <ul><li>Chemical - rocks form from minerals that have been dissolved in water </li></ul><ul><li>Organic - rocks are the remains of living things </li></ul>
  21. 25. <ul><li>Clastics </li></ul><ul><li>Clastics are identified by the size of their sediment </li></ul><ul><li>Conglomerate- rounded. pebble size </li></ul><ul><li>Breccia- angular pebble size </li></ul><ul><li>Sandstone - sand sized particles </li></ul><ul><li>Shale - clay particles </li></ul>
  22. 26. <ul><li>Conglomerate- rounded. pebble size </li></ul>
  23. 27. Conglomerate
  24. 28. <ul><li>Breccia- angular pebble size </li></ul>
  25. 29. Breccia
  26. 30. <ul><li>Sandstone - sand sized particles </li></ul>
  27. 31. Sandstone
  28. 32. <ul><li>Shale - clay particles </li></ul>
  29. 33. Shale
  30. 34. <ul><li>Chemical </li></ul><ul><li>Some minerals precipitate due to a change in temperature, limestone </li></ul><ul><li>Evaporates -left behind when water evaporates gypsum, halites </li></ul>
  31. 35. Limestone
  32. 36. Rock salt and Gypsum
  33. 37. <ul><li>Organic </li></ul><ul><li>Coal -formed from plants being buried then compacted </li></ul><ul><li>Organic limestone -shells from clams, coral, oysters and plankton form limestone </li></ul>
  34. 38. Coal
  35. 39. Organic Limestone
  36. 40. <ul><li>Features </li></ul><ul><li>Stratification-layer representing conditions when formed. cross-bedding </li></ul><ul><li>Ripple marks and mud cracks </li></ul><ul><li>Fossils </li></ul><ul><li>Concretions precipitated minerals build up around existing rocks </li></ul>
  37. 41. Concretion
  38. 42. <ul><li>Metamorphic rocks </li></ul><ul><li>Rock may change because of exposure to heat and pressure, or have minerals dissolved or added </li></ul><ul><li>Two types metamorphism </li></ul><ul><ul><li>Contact (direct) </li></ul></ul><ul><ul><li>Regional (Barrovian) </li></ul></ul>
  39. 44. <ul><li>Classification </li></ul><ul><li>Foliation </li></ul><ul><ul><li>metamorphic rock has visible stripes </li></ul></ul><ul><li>Can be formed when crystals are pushed into parallel bands or minerals of different densities separate into bands </li></ul>
  40. 45. Schist
  41. 46. <ul><li>Banding </li></ul><ul><ul><li>Minerals form into district lines, </li></ul></ul><ul><ul><li>Requires more heat and pressure than foliation </li></ul></ul><ul><ul><li>Both take flat minerals like mica and force them into bands </li></ul></ul>
  42. 47. Gneiss
  43. 48. <ul><li>Example of formation </li></ul><ul><li>Slate, schist and gneiss </li></ul><ul><li>Slate comes from shale </li></ul><ul><li>More heat and pressure turn slate in schist </li></ul><ul><li>Schist transforms into gneiss </li></ul>
  44. 49. <ul><li>Unfoliated </li></ul><ul><li>Have no bands </li></ul><ul><li>Formed from rocks with one mineral </li></ul><ul><li>Quartzite formed from sandstone </li></ul><ul><li>Marble formed from limestone </li></ul>
  45. 50. Slate
  46. 51. Quartzite
  47. 52. Marble
  48. 53. Images from about.geology.com

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