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Sedimentary Rocks: Formation, Importance, and Environmental Clues

Study the formation, economic importance, and environmental clues provided by sedimentary rocks. Discover how these rocks hold valuable resources, provide fresh water sources, and contain crucial information about Earth's ancient environments and the evolution of life.

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Sedimentary Rocks: Formation, Importance, and Environmental Clues

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  1. WHAT HAPPENS TO THE PRODUCTS OF ROCK WEATHERING Weathering Transport Deposition

  2. II. Sedimentary Rocks

  3. WHY STUDY SEDIMENTARY ROCKS? • Cover over 70% of Earth’s Land Surface • These are the rocks you see most often. • 2) Economically Important!! • Contain all oil & gas deposits • Important source of mineral resources like iron, salt, aluminum; of agricultural fertilizer; of construction materials like gypsum for drywall. • Sedimentary rocks form important aquifers – sources of fresh drinking water.

  4. WHY STUDY SEDIMENTARY ROCKS? 3) They retain information about how and where they formed. Important clues to Earth’s ancient environments! 4) They contain fossils. Important information on the history and evolution of life!!

  5. WHY STUDY SEDIMENTARY ROCKS? They can be incredibly beautiful!!

  6. II. Sedimentary Rocks: Two Types • Clastic: Rocks that form from the lithification (compaction and cementation) of the weathered and eroded products of pre-existing rocks. • Chemical: Rocks that form from the crystallization of minerals out of water (usually sea water).

  7. Clastic Sedimentary Rocks • Rock names are based on the size of the particles that form the rock. or Breccia Siltstone Shale

  8. CONGLOMERATE SANDSTONE SHALE

  9. Chemical Sedimentary Rocks Can be chemical or biochemical precipitates 1) Limestone (CaCO3) – Composed of the mineral calcite. Several different varieties. a) Fossiliferous limestone b) Lithographic limestone c) Oolitic Limestone d) Coquina e) Travertine 2) Dolostone (CaMg(CO3)2) – Compsed of the mineral dolomite.

  10. Fossiliferous Limestone Travertine Deposits Coquina – Fossil Hash Chert Nodules in Limestone

  11. Chemical Sedimentary Rocks 3) Chert – microcrystalline quartz. 4) Evaporites – halite, gypsum, annhydrite Devil’s Golf Course – Salt Crystals, Death Valley, CA

  12. INTERPRETING SEDIMENTARY ENVIRONMENTS: Rocks contain a complex and beautiful story about the Earth’s history. To unravel this story we must learn to read the language of geology.

  13. Clues To Interpreting Sedimentary Rocks 1) Transport History

  14. Clues To Interpreting Sedimentary Rocks 2) Sedimentary Structures A) Ripple Marks – modern beach

  15. Ripple Marks in Sandstone – Rock was formed on an ancient beach

  16. 2) Sedimentary Structures B) Cross Beds – the inside of Ripple Marks

  17. Checkerboard Mesa – Zion National Park, Utah

  18. 2) Sedimentary Structures C) Mud Cracks – Environment that periodically dries out

  19. 2) Sedimentary Structures D) Graded Bedding – Which way is up?

  20. Kissing Camels – Garden of the Gods, Colorado

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