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sedimentary rocks

Learn about the formation of sedimentary rocks through compaction and cementation. Explore clastic, crystalline, and bioclastic rock types. Discover famous geological formations and fossils. Watch a video on clastic sedimentary rocks.

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sedimentary rocks

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  1. sedimentary rocks

  2. A. Formation: 1. Sedimentary rocks form from the COMPACTION & CEMENTATIONof rock fragments/sediments 2. Lithification: the changing of sediments into sedimentary rock

  3. 3. Sedimentary rocks are similar to the sediments from which they form (ie. Sandstone is made up of sand)

  4. B. CLASTIC 1. Form when rock fragments & sediment are carried & deposited by GRAVITY, WIND, GLACIERS, & RUNNING WATER

  5. Clastic Rock Formation

  6. Most sediment is carried byRunning Water 2. The farther water carries sediment, the ROUNDER & SMOOTHERthe sediment becomes 3. When a stream slows down, it drops the LARGESTparticles first, & the SMALLESTlast (HORIZONTAL SORTING)

  7. Observe how sediments are deposited

  8. So…. • If you are far out from shore, would you expect the grain size of the rocks to be large or small? • What about if you are close to the shore?

  9. That means…. 4. Rocks formed closer to shore will be made up of bigger fragments than rocks formed farther away from the shore

  10. Conglomerate – large sediments that are rounded (have been transported by a stream!) Breccia – very large sediments that are angular, most likely deposited by gravity

  11. C. CRYSTALLINE 1. Formed when dissolved minerals in seawater are deposited (seawater evaporates, leaving the minerals behind to crystalize) 2. Also known as CHEMICAL

  12. Salt “Mines” - Rock Salt is being formed as the salt water evaporates from the sea.

  13. “Devil’s Golf Course” – millions of years ago this was a sea of salt water. It has been evaporating over time… …and has formed “pockets” of chemical limestone, rock salt, and rock gypsum!

  14. D. BIOCLASTIC 1. Formed from the remains of plants & animals that are compacted • Fossil Limestone – formed when shell remains of marine organisms are cemented in fragments • Shells are made of CALCITE which reacts with acid

  15. 2. Coal Formation

  16. a. Long ago, huge trees grew in the warm, humid swamps. b. Trees died and decomposed into what is called PEAT c. Peatwas buried under layers ofmud. d. Pressure increased, slowly changing the plant remains intocoal. Coal – note distinct layering of peat

  17. ESRT page 7

  18. STRATIFICATION 1. STRATIFICATION (layering): Layers of sediments that have SIMILARLY colored minerals and are typically sandstones or siltstones

  19. 2. Fossils – actual remains, imprints from plants or animals, or preserved traces from living things

  20. bells & whistles for sedimentary rock identification! • Stratification • Fossils • Fragments of materials cemented together • Ripple marks • Mud cracks

  21. Angel’s Landing, Zion Nat’l Park, Utah – note rock layers

  22. Red Sandstone, Utah – note distinct LAYERING of sediments (sand)

  23. Horseshoe Bend, Utah

  24. Grand Canyon Nat’l Park, Arizona – sedimentary rock formation at its best! The canyons were formed by the Colorado River cutting into the rock layers over time!

  25. Fossils • The remains, impression or any other evidence of a plant or animal preserved in rock. • Fossilization

  26. Brachiopod fossils in limestone Imprint of a leaf Trilobite fossils – over 250 MILLION years old!!!

  27. Mud Cracks and Ripples • Ripple Marks: A sand pattern formed by the action of winds, streams, waves or currents; preserved when sand becomes sandstone • Mud Cracks: Develop when deposits of wet clay dry and contract. The cracks are filled with sediments and fossilize when the clay becomes shale

  28. Ripple Marks in the Shale from running water as the rock was forming

  29. Video Watch the video and jot down 3 notes about it in your notes https://www.youtube.com/watch?v=eOuPsJwYu9I If the video doesn’t show, search for Geologist Kitchen Clastic Sedimentary Rocks

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