Sedimentary rocks


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Sedimentary rocks

  1. 2. - 75% of the rocks exposed at the surface are sedimentary rocks.
  2. 3. - sediments are loose materials such as rock fragments, mineral grains, and bits of plant and animal remains that are moved by wind, water, ice, or gravity.
  3. 4. - sedimentary rock forms when sediments are pressed and cemented together, or when minerals form from solutions.
  4. 6. - sedimentary rocks often form in layers
  5. 7. - older rocks are usually found at the bottom layers, however, sometimes forces within Earth overturn layers of rock, and the oldest are no longer at the bottom.
  6. 9. - sedimentary rocks are usually classified as detrital, chemical or organic. <ul><li>detrital = clastic </li></ul><ul><li>chemical and organic = nonclastic </li></ul><ul><li>* you need to know all of these terms!!! </li></ul>
  7. 10. - Detrital sedimentary rocks: made from broken fragments of other rocks
  8. 11. 1. when rock is exposed to air, water, or ice, it is unstable and breaks down. This process, which breaks rocks into smaller pieces, is called weathering.
  9. 12. 2. when layers of small sediments stick together because of pressure, compaction occurs.
  10. 13. 3. when water and other minerals (such as quartz, calcite and hematite, which act as naturally glues) move through open spaces between larger sediments, gluing them together, cementation occurs.
  11. 14. 4. Detrital rocks have granular textures, much like granulated sugar. They are named according to the shapes and sizes of the sediments that form them. Breccia: angular Conglomerate: rounded
  12. 15. <ul><li>Big Sediments Conglomerate (round pebbles) </li></ul><ul><ul><li>boulders </li></ul></ul><ul><ul><li>pebble </li></ul></ul><ul><ul><li>gravel </li></ul></ul><ul><ul><li>sand sandstone (feels sandy, has pores) </li></ul></ul><ul><ul><li>silt shale (feels smooth, pressure from layers) </li></ul></ul><ul><ul><li>clay </li></ul></ul><ul><ul><li>Small Sediments </li></ul></ul>
  13. 16. Chemical sedimentary rocks: form when dissolved minerals come out of solution. <ul><li>- chemical sedimentary rocks are different: they are not made from pieces of preexisting rock. </li></ul>
  14. 17. - limestone: when calcium carbonate comes out of solution in the form of calcite
  15. 18. - limestone is usually deposited on the bottom of lakes or shallow seas.
  16. 19. - large areas of the central U.S. have limestone bedrock because seas covered much of the country for millions of years.
  17. 20. - The mineral halite forms rock salt when water that is rich in dissolved salt evaporates.
  18. 21. Michigan Basin
  19. 22. - companies mine deposits of rock salt as an important resource.
  20. 23. - Organic Sedimentary Rocks: made from remains of once-living plants or animals.
  21. 24. - fossil-rich limestone: similar to chemical limestone (both made of calcite) however, fossil-rich limestone mostly contains remains of once-living ocean organisms instead of only calcite.
  22. 26. - chalk is made of microscopic shells.
  23. 27. - coal is made of plant remains, chemically changed by microorganisms compacted over millions of years.
  24. 28. - The rock cycle is a continuous and dynamic process.