2. Sedimentary Rx pages 548-557  For thousands, even millions of years, little pieces of our earth have been eroded-- broken down and worn away by wind and water. These little bits of our earth are washed downstream where they settle to the bottom of the rivers, lakes, and oceans. Layer after layer of eroded earth is deposited on top of each. These layers are pressed down more and more through time, until the bottom layers slowly turn into rock. http://www.fi.edu/fellows/payton/rocks/create/sediment.htm

3. Sedimentary rock is  Most common rock at Earth's surface  Thin blanket over 2/3 of the surface covering igneous and metamorphic rocks

4. FossilsFossils are often found in sedimentary rock. FossilsFossils are often found in sedimentary rock.  Ammonite  Fossil fish

5. Sedimentation  Volcanism builds new rocks  Weathering breaks them down into sediments

6. Two types of weathering: Mechanical and Chemical

7. Mechanical weathering Mechanical weathering breaks rock into smaller pieces Mechanical weathering Mechanical weathering breaks rock into smaller pieces Three ways Frost wedging Root wedging Gravity

8. Mechanical weathering Mechanical weathering increases the surface area of the rock exposed to chemical weathering Mechanical weathering Mechanical weathering increases the surface area of the rock exposed to chemical weathering

9. 2. Chemical WeatheringChemical Weathering 2. Chemical WeatheringChemical Weathering Chemical Reactions with water dissolve rock H 2 O + CO 2 H 2 CO 3 Water and carbon dioxide yields carbonic acid This is what dissolves limestone and makes caves

10. Erosion  Erosion--movement of seds  What can move it ? (Agents of erosion) Wind Water Ice  The larger the sediment the harder it is to move

11. DepositionDeposition— seds are deposited DepositionDeposition— seds are deposited  When deposited sediment accumulates, it begins to transform into sedimentary rock

12. Two types of sedimentary rocks  Clastic Made of bits and pieces of recycled rock Chemical Form by precipitation or evaporization Called Precipitates and evaporites

13. Transformation Transformation of Clastic rocks occurs in two ways: Transformation Transformation of Clastic rocks occurs in two ways:  Compaction seds are pressed together – grains interconnect  Cementation Seds are cemented together like glue – Calcite, – silica, and – iron oxide are the most common cements.

14. Clastic sediments bits and pieces of old rock/plants/animals  Clastic sedimentary rocks are classified by their sediment size and shape Most common is shale--very fine particles Sandstone—sand sized particles Siltstone—silt size

16. Rounder seds mean longer transport

17. And by shape of seds Conglomerate- rounded seds

18. Breccia—angular seds

19.  Egyptian statue made from breccia

20. Chemical Sediments  Chemical sediments precipitate from water Two types – Carbonates – Evaporites

21. Carbonates Made of mostly calcite Ca CO 3 or CaMg CO 3  Limestone is CaCO 3 Very common here  Dolomite is CaMgCO 3 Some of the carbonate is replaced by magnesium

22. Evaporites  Evaporites evaporate from water when a basin dries up Gypsum CaSO 4. H 2 O Halite (Rock Salt) NaCl

23. Halite--—a salt playa

24. Sedimentary Rock Lab  Name the rocks you find in your sample bag.  Choices Sandstone Coal Conglomerate Coquina Gypsum Rock salt Oolitic limestone

25. Sed rock Sed rock review Sed rock Sed rock review  A sed rock quiz A sed rock quiz

26. Sedimentary environments  Sedimentary rocks provide information about events that occurred on Earth's surface  Their color, grain size, and composition give us information about what was happening when they formed

27. Sedimentary rock environmentsSedimentary rock environments

28. Crossbedding Crossbedding and Ripple Marks Crossbedding Crossbedding and Ripple Marks  Crossbedding gives us an indication of wind or water direction Crossbedding  Ripple marks may be Symmetrical-oscillating Asymmetrical- current ripple marks

29. CavesCaves form in sedimentary rock CavesCaves form in sedimentary rock

30. Depositional Environments  Delta -a fan-shaped body formed when water flows from a stream into a standing body of water  Example the Mississippi River Delta Mississippi River Delta The Nile River Delta

31. Environments  River—Alluvial  Desert--aeolian  Delta  Shoreline

32. Alluvial--River Channel  Unconsolidated gravels, sand, and clay

33. Alluvial Fan  Forms when sediment flows from a steep incline onto a flat floored valley and looses velocity rapidly  Seds are laid down the largest first, followed by progressively smaller and smaller as the velocity slows

34. Oxbow lake formation  An oxbow lake occurs between here and Oxford

35. Conglomerate- rounded seds Rounded seds indicate a longer distance of transport

36. Evaporites ---Gypsum Ca SO 4. H 2 O Halite (Rock Salt) NaCl

37. Gypsum

38. Sandstone would indicate a beach or desert was once there

39. Limestone

40. Sedimentary environment

41. What ancient environment would produce the following:

42. A REEF  a. A linear outcrop of fossiliferous limestone, massive bedding, many corals and algal structures

44. SAND DUNES  b: cross-bedded, well-sorted sandstone, with frosted quartz grains

45. c: Unsorted, unstratified, the angular boulders have scratches GLACIAL

46. A Glacial Moraine

47. d. Unsorted, unstratified, the the angular boulders don't have scratches. ALLUVIAL FAN

49. Name this structure

50. e: poorly sorted, but somewhat stratified sandstone and conglomerate with cut and fill structures. RIVER

51. f: very fine parallel bedding, diatoms, red clay, some thin graded bedding. DEEP OCEAN

52. g. Thick deposits rock salt and gypsum. RESTRICTED CONTINENTAL SEAS

53. Jurassic Seaway- example of a continental sea

54. h. Fine-grained sand (made of shell fragments) with ripple marks and worm burrows. LAGOON BEHIND REEF