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Color, Trace Fossils, Weathering, and Soils

Color, Trace Fossils, Weathering, and Soils. Causes of Color Common Trace Fossils Weathering Processes - Physical Weathering - Chemical Weathering Weathering Products - Soils - Paleosols. Text: Manual p. 15, 89; Boggs Ch.1, 114-122 . Causes of Color. color. mineral.

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Color, Trace Fossils, Weathering, and Soils

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  1. Color, Trace Fossils, Weathering, and Soils • Causes of Color • Common Trace Fossils • Weathering Processes • - Physical Weathering • - Chemical Weathering • Weathering Products • - Soils • - Paleosols Text: Manual p. 15, 89; Boggs Ch.1, 114-122

  2. Causes of Color color mineral occurrence

  3. Color, Trace Fossils, Weathering, and Soils • Causes of Color • Common Trace Fossils • Weathering Processes • - Physical Weathering • - Chemical Weathering • Weathering Products • - Soils • - Paleosols Text: Manual p. 15, 89; Boggs Ch.1, 114-122

  4. Trace Fossils Environment Ichnofacies (Boggs, p. 118)

  5. Color, Trace Fossils, Weathering, and Soils • Causes of Color • Common Trace Fossils • Weathering Processes • - Physical Weathering • - Chemical Weathering • Weathering Products • - Soils • - Paleosols Text: Manual p. 15, 89; Boggs Ch.1, 114-122

  6. Physical Weathering Physical Weathering: Break-down rock into smaller pieces • no change in mineral / chemical composition

  7. 3. Granite Grus 2. Partially-Weathered Granite Physical Weathering 1. Granite

  8. Physical Weathering • roots / lichens • freeze-thaw • wet-dry • hot-cold

  9. Physical Weathering

  10. Physical Weathering Enchanted Rock batholith Exfoliation http://www.governor.state.tx.us/

  11. Physical Weathering Spheroidal Weathering Costa Rica

  12. Physical Weathering Gullying Painted Desert, Utah

  13. Physical Weathering Bryce Canyon

  14. Chemical Weathering Chemical Weathering: Dissolution and/or crystallization of new minerals • alter chemical and mineral composition • disrupt fabrics

  15. Chemical Weathering Hydrolysis: H+ breaks down silicates Feldspar + H+ + H2O  kaolinite + silicic acid + K+ or Na2+

  16. Chemical Weathering pyrite Oxidation / Reduction: O alters Fe silicates and S minerals silicate mineral  Fe-oxide pyrite pyrite  hematite http://web.wt.net/~daba/Mineral/index.htm

  17. Chemical Weathering Fe-oxide Stains Bastrop, TX (E. McBride)

  18. Chemical Weathering pyrite Solution: dissolve in water calcite / dolomite gypsum halite (E McBride) http://www2.nature.nps.gov/ Limestone Karen Rills

  19. Physical/Chemical Weathering Differential Weathering cliff slope bench Grand Canyon

  20. Physical/Chemical Weathering Differential Weathering “Toadstools” Utah

  21. Physical/Chemical Weathering Differential Weathering burrows

  22. Color, Trace Fossils, Weathering, and Soils • Causes of Color • Common Trace Fossils • Weathering Processes • - Physical Weathering • - Chemical Weathering • Weathering Products • - Soils • - Paleosols Text: Manual p. 15, 89; Boggs Ch.1, 114-122

  23. Weathering Products • clastic sediments • residues (source rock) • secondary minerals • ions in solution Soils and Sed. Rocks

  24. Weathering Products Terrigenous Clastic Sediments

  25. Weathering Products Chemical Sediments Cements (M. Campbell) Evaporites Death Valley, CA www.geol.binghamton.edu/faculty/lowenstein/dv/deathvalley.html courtesy Matt Campbell

  26. Soils Soil Profile Horizons • mineral residues • rock fragments • organics http://www.cjnetworks.com/

  27. Soils Soil Profile Horizons O - organic matter A - topmost mineral horizon E - (eluvial) leaching B - (illuvial) accumulation C - weathered bedrock R - bedrock http://www.cjnetworks.com/

  28. Soils • bedrock • time • climate • topography

  29. 30 inches of rain per year Pedocal Soils Pedalfer Soils Soils http://www.mhhe.com/earthsci/geology/mcconnell/wss/soil.htm

  30. Soils • color • texture • structure • consistency • contacts

  31. Soils Texture

  32. FIGURE 3-26 FIGURE 3-28 Soils Structure FIGURE 3-30 columnar blocky platy crumb FIGURE 3-29

  33. Soils Consistency: Plasticity

  34. Soils Standard USDA Soil Description Form

  35. Color, Trace Fossils, Weathering, and Soils • Causes of Color • Common Trace Fossils • Weathering Processes • - Physical Weathering • - Chemical Weathering • Weathering Products • - Soils • - Paleosols Text: Manual p. 15, 89; Boggs Ch.1, 114-122

  36. Paleosols

  37. Paleosols • colors (red, green, purple) • root casts • caliche • vertical streaks • mottled bedding

  38. Paleosols Paleosols Painted Desert, AZ

  39. Paleosols Paleosol, near Hunt, TX Root Casts

  40. Paleosols Paleosol Bastrop, TX (E. McBride) vertical streaks (bleaching)

  41. Paleosols (E. McBride) “terra rossa” fill

  42. Reference Soil Survey Manual, 1993, Soil Conservation Service, USDA Handbook 18.

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