1. 1 Lab 06 ONLINE LESSON Use down or up arrows to navigate

2. 2 DO TAKE NOTES WHILE PERUSING ALONG…

3. 3 Sedimentary Rocks

4. 4 As we saw last time, a rock is a collection of minerals…

5. 5 There’s a mineral

6. 6 A sedimentary rock is comprised of pieces of other rocks called sediment…

7. 7 There’s a sediment

8. 8 The Rock Cycle tells us that rocks first start out as igneous rocks…

9. 9 Eventually, these rocks undergo changes…

10. 10 Weathering is the process of breaking up rocks…big rocks turn into small rocks

11. 11 Sediment (small rocks) is transported and deposited where it forms into sedimentary rock…

12. 12 So a sedimentary rock is just a collection of rock particles called sediment…

13. 13 Weathering is the process of breaking rocks apart…

14. 14 There are two types of weathering… Chemical Mechanical

15. 15 Chemical weathering is caused by chemicals that come in contact with minerals……

16. 16 One chemical is water… H 2 O

17. 17 Water will come in contact with halite…

18. 18 Water will break up the halite…

19. 19 Halite is broken down into its constituent elements of sodium (Na + ) and chloride(Cl - )

20. 20 This is chemical weathering…

21. 21 Another example of chemical weathering…

22. 22 CaCO 3 + H 2 CO 3 - → Ca 2+ + 2HCO 3 - Acids will break down minerals…… calcite Carbonic Acid

23. 23 Calcite plus carbonic acid will break down to form calcium and bicarbonate…

24. 24 Mechanical Weathering is caused by mechanical actions

25. 25 In other words…rocks are broken down by a pushing, pounding or scraping force…

26. 26 Frost Wedging = low atmospheric temperatures will break up rocks

27. 27 Water in cracks will freeze causing the expanding water to break up rocks…

28. 28 The result is sediment

29. 29 Landslides are another form of mechanical weathering…

30. 30 Rocks under the force of gravity will fall down and break up on impact with the ground…

31. 31 Punch the dinosaur to see a video of some jokers producing an artificial mechanical weathering

32. 32 Did you see that? A large sandstone was pushed over the cliff…fell and broke into smaller rocks…

33. 33 Mechanical weathering in action!

34. 34 So, weathering breaks up rocks…by the way, these rocks are generally referred to as Clastic Sedimentary Rocks…

35. 35 Clastic meaning that rocks are broken up into fragments…

36. 36 So how do sediments make rocks?

37. 37 In addition to weathering… transportation, deposition and lithification of sediments must take place…

38. 38 Transportation is the movement of sediment…

39. 39 Streams are a common mechanism of transportation…

40. 40 Stream is just another word for a river…

41. 41 Streams can carry large quantities of sediment…as long as streams move, sediment is transported…

42. 42 Streams move…sediments move…

43. 43 However, once a stream stops moving, then sediments will be deposited…

44. 44 Deposition occurs when a mechanism of transportation stops…

45. 45 Streams stop…sediments dropout of moving water…

46. 46 Deposition occurs…

47. 47 The result….

48. 48 A sedimentary rock…

49. 49 Such as this sandstone…

50. 50 It is made out of sand…

51. 51 It is a result of mechanical weathering…

52. 52 transportation…

53. 53 and deposition…

54. 54 Once sediment has deposited…it then undergoes lithification

55. 55 Lithification is the process of turning loose sediment into a solid rock…

56. 56 Lithification involves cementation and compaction

57. 57 Compaction Sediment is pushed together

58. 58 Cementation A binding agent is introduced…

59. 59 Cementation to glue sediment together

60. 60 SEDIMENT CEMENTCEMENT

61. 61 Cementation process utilizes… CaCO 3 SiO 2 Fe 2 O 3

62. 62 These are binding agents…That form Clastic Sedimentary Rocks

63. 63 Characteristics of clastic sedimentary rocks… GRAIN SIZE

64. 64 Sediments are formed into a number of sizes…

65. 65 Sizes are listed in metric form

66. 66 So grain size is used to categorize sedimentary rocks…

67. 67 A rock with grains 2mm in size is called a sandstone…

68. 68 A rock with grains 1/256 mm in size is called a shale…

69. 69 A rock with a larger grain size is called a Breccia or Conglomerate…

70. 70 Breccia and conglomerate are based on the roundness of sediments...

71. 71 Characteristics of clastic sedimentary rocks… SORTING

72. 72 Sorting is the arrangement of the grains of sediment…

73. 73 Sorting A collection of very large and very small grain sizes

74. 74 Sorting A collection of less differing grain sizes

75. 75 Sorting A collection of almost the same sized grains

76. 76 Sorting is an indicator of the speed of a stream

77. 77 A fast stream produces a well sorted sediment…

78. 78 A stream of fluctuating speeds produces poorly sorted sediments…

79. 79 Characteristics of clastic sedimentary rocks… ROUNDING

80. 80 Rounding refers to the degree to which sharp corners have been worn away…

81. 81 Rounding

82. 82 Rounding

83. 83 Rounding

84. 84 Rounding indicates the amount of transportation a sediment has undergone

85. 85 The more transportation, the smoother the grain…less transportation, the more angular the grain…

86. 86

87. 87

88. 88

89. 89 Another form of sedimentary rock are Biochemical Sedimentary Rocks…

90. 90 Biochemical sedimentary rocks are made up of the remnants of once living organisms…

91. 91 Here is a coquina…

92. 92 It is made up of shell fragments of marine organisms…

93. 93 Some biochemical rocks contain invisible fragments…

94. 94 Such as this chalk

95. 95 Some biochemical rocks react with acid

96. 96 REVIEW

97. 97 Sedimentary Rocks are made of sediment…

98. 98 Sediment is a result of Chemical weathering Mechanical weathering

99. 99 Sedimentary Rocks are grouped into Clastic Biochemical

100. 100 Characteristics of clastic sedimentary rocks Sorting Rounding

101. 101 Sorting Well sorted Moderately sorted Poorly sorted

102. 102 Rounding Very angular grains Subangular grains Well rounded grains

103. 103 Grain Size

104. 104 A note: Terms such as aphanitic, phaneritic and so on are not applied to sedimentary rocks…

105. 105 It is now time for a short assignment….ask Bob for a worksheet…