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  1. 1. Chapter 12 Earth’s Internal Structure, Rock Cycle, and Geologic Time
  2. 2. Earth’s Internal Structure
  3. 3. The Cores <ul><li>Inner </li></ul><ul><ul><li>Solid -> pressure > heat </li></ul></ul><ul><li>Outer </li></ul><ul><ul><li>Liquid -> heat > pressure </li></ul></ul><ul><ul><li>Creates ____magnetosphere____ </li></ul></ul><ul><li>How? </li></ul>
  4. 4. <ul><li>Asthenosphere </li></ul><ul><ul><li>“without _strength_” </li></ul></ul><ul><ul><li>Is part of the upper mantle </li></ul></ul><ul><ul><li>Molten rock </li></ul></ul><ul><li>Lithosphere </li></ul><ul><ul><li>“_stone_” </li></ul></ul><ul><ul><li>Includes the upper part of the asthenosphere </li></ul></ul><ul><ul><li>Slides over the upper mantle </li></ul></ul><ul><ul><li>Location for earthquakes, volcanoes, & continental drifts occur </li></ul></ul>
  5. 5. The Crusts <ul><li>Oceanic Crust </li></ul><ul><ul><li>Mostly ___basalt___ </li></ul></ul><ul><ul><li>Thinner and denser than continental </li></ul></ul><ul><li>Continental Crust </li></ul><ul><ul><li>Mostly granite </li></ul></ul><ul><ul><li>Thickest beneath mountain ranges </li></ul></ul><ul><ul><li>Thinnest in ___Rift Valley Africa____ </li></ul></ul>
  6. 6. Rocks and Minerals of the Crust <ul><li>Minerals </li></ul><ul><ul><li>Naturally occurring with distinct configurations in crystalline form </li></ul></ul><ul><li>Rocks </li></ul><ul><ul><li>2+ minerals bonded in solid state </li></ul></ul><ul><ul><li>3 Major types </li></ul></ul><ul><ul><ul><li>Igneous </li></ul></ul></ul><ul><ul><ul><li>Sedimentary </li></ul></ul></ul><ul><ul><ul><li>Metamorphic </li></ul></ul></ul>
  7. 7. Igneous <ul><li>Form from solidification of molten magma </li></ul><ul><ul><li>Extrusive </li></ul></ul><ul><ul><ul><li>Cools _____on surface________ </li></ul></ul></ul><ul><ul><li>Intrusive </li></ul></ul><ul><ul><ul><li>Cools _____within the crust_____ </li></ul></ul></ul>
  8. 8. Obsidian Gabbro Basalt Granite Pumice Intrusive Pyroclastic Extrusive
  9. 9. Intrusive Igneous Rock Examples Horizontal spread Vertical spread Huge; unknown depth Horizontal spread that warps rocks above it Types of _________
  10. 10. Batholith
  11. 11. Sill
  12. 12. Dikes
  13. 13. Silicate Minerals and Igneous Rocks
  14. 14. Mafic Igneous Minerals <ul><li>Mafic: “m” for magnesium, “f” for Fe (iron) </li></ul><ul><li>Silicates containing magnesium and iron </li></ul><ul><li>Mafic minerals are denser and heavier than felsic minerals </li></ul><ul><li>Color? </li></ul>
  15. 15. Felsic Igneous Minerals <ul><li>Felsic: “fel” for feldspar “si” for silicate </li></ul><ul><li>Feldspars </li></ul><ul><ul><li>silicate-aluminum minerals, as well as K, Na, Ca, </li></ul></ul><ul><li>Felsic minerals are lighter in color and less dense than mafic minerals </li></ul>
  16. 16. Igneous Rock Felsic Mafic Granite Extrusive Intrusive Rhyolite Gabbro Basalt
  17. 17. Sedimentary Rocks <ul><li>Form from burial, compression and chemical modification </li></ul><ul><ul><li>e.g. ________ and ___________ of materials </li></ul></ul>
  18. 19. Classes of Sediments <ul><li>Clastic (composed of fragments = clasts ) </li></ul><ul><li>Chemically precipitated sediment </li></ul><ul><li>Organic sediment </li></ul>
  19. 20. Clastic Sedimentary Rocks <ul><li>Consist of inorganic rock and mineral fragments </li></ul><ul><ul><li>quartz most important component </li></ul></ul><ul><li>“ _______” - separation of particles by size </li></ul><ul><ul><li>determines texture of rock </li></ul></ul><ul><li>Compaction and cementation </li></ul><ul><ul><li>Cementation occurs when dissolved minerals recrystallize </li></ul></ul><ul><ul><ul><li>_______ and __________ are common cements </li></ul></ul></ul>Clastic sedimentation - hyperlink
  20. 21. Common Clastic Sedimentary Rocks <ul><li>Classified by size of particles </li></ul><ul><li>Sandstone </li></ul><ul><ul><li>fine to coarse cemented sand </li></ul></ul><ul><li>Conglomerate – </li></ul><ul><ul><li>sandstone with mutlisized pebbles </li></ul></ul><ul><li>Siltstone, claystone, mudstone </li></ul><ul><ul><li>________ – any of the above that break easily into small flakes </li></ul></ul><ul><ul><li>usually __________ and ______ easily </li></ul></ul>
  21. 22. Sandstone Shale Conglomerate
  22. 23. Chemically Precipitated Sedimentary Rocks <ul><li>Precipitation and recrystallization </li></ul><ul><ul><li>Carbonate rocks: </li></ul></ul><ul><ul><ul><li>limestone : calcium carbonate (calcite) </li></ul></ul></ul><ul><ul><ul><li>dolomite : calcium-magnesium carbonate </li></ul></ul></ul><ul><ul><li>Chert : silica in hard noncystalline form </li></ul></ul><ul><li>Evaporites: _________________________ </li></ul><ul><li>- halite - rock salt </li></ul>
  23. 24. Dolomite Halite Limestone
  24. 25. Organic Sediments <ul><li>Large accumulations of plant remains </li></ul><ul><li>Hydrocarbon deposits (“fossil fuels”): </li></ul><ul><ul><li>solids: peat (histosols) and coal </li></ul></ul><ul><ul><li>liquids and gases (mineral fuels): </li></ul></ul><ul><ul><ul><li>petroleum </li></ul></ul></ul><ul><ul><ul><li>natural gas </li></ul></ul></ul>
  25. 26. Peat Coal
  26. 27. Metamorphic Rocks <ul><li>“to ______________” </li></ul><ul><li>Existing rock is modified </li></ul><ul><li>Form from: </li></ul><ul><ul><li>________ and ___________ </li></ul></ul><ul><ul><li>Contact with invading magma – batholiths, dikes, sills </li></ul></ul><ul><li>Mineral components are rearranged </li></ul><ul><li>Look for banding </li></ul>
  27. 28. Slate Gneiss
  28. 29. Rock Cycle
  29. 30. Geologic Time <ul><li>“deep time” </li></ul><ul><li>Def: the period of time that encompasses all of Earth history, from its formation to present </li></ul>
  30. 31. <ul><li>Universe: 14 BY </li></ul><ul><li>Earth: 4.6 BY </li></ul><ul><li>Large to small </li></ul><ul><ul><li>Eons </li></ul></ul><ul><ul><li>Eras </li></ul></ul><ul><ul><li>Periods </li></ul></ul><ul><ul><li>Epochs </li></ul></ul>
  31. 32. Telling Geologic Time: Radiometric Dating <ul><li>Measure amount of radioactive decay of rocks </li></ul><ul><li>Radioactive isotopes </li></ul><ul><ul><li>Unstable isotopes change from one element to another </li></ul></ul><ul><ul><li>Radiation is emitted in the process </li></ul></ul><ul><ul><li>_____________ – the amt of time required for ½ of the isotopes in any sample to decay </li></ul></ul>
  32. 33. The Grand Canyon and Geologic Time
  33. 34. The Geologic Time Scale Related to the Calendar Year Dec. 31 (0.05 seconds before midnight) 18 Your birth Dec. 31, 6 P.M. 3 my Early hominids Dec. 31, 5 A.M. 10 my Grand Canyon downcutting Dec. 18 155 my First mammals Dec. 13 220 my First reptiles Dec. 3 340 my First land plants Nov. 10 625 my First vertebrates Oct. 12 1.0 by First cell with nucleus mid-July 2.0 by Oxygen in atmosphere mid-April 3.2 by First single-celled organism Jan. 1 4.6 by Earth formed Time in Year Age Event