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Geosciences LibreTexts

6: Sediments and Sedimentary Rocks (Exercises)

  • Page ID
    2045
  • [ "article:topic" ]

    Q6.1 Describe the sediment on a beach

    Responses will vary

    Q6.2 Classifying sandstones

    Description Rock name
    Angular grains, 85% quartz, 15% feldspar, <5% silt and clay Arkosic arenite
    Rounded grains, 99% quartz, <2% silt and clay Quartz arenite
    Angular grains, 70% quartz, 20% lithic and 10% feldspar, ~20% silt and clay Lithic wacke

    Q6.3 Making evaporite

    Responses will vary

    Q6.4 Interpretation of past environments

    Description Source rock Weathering Transportation Dep. environment
    Cross-bedded quartz sandstone, rounded grains probably sandstone strong chemical weathering wind desert
    Feldspathic sandstone and mudstone with volcanic fragments and repetitive graded bedding granite and volcanic rock weak chemical weathering short transport in a river sub-marine fan
    Conglomerate with well- rounded pebbles and cobbles, imbricated granite and volcanic rock difficult to tell high-energy river moderate energy river
    Limestone breccia with orange-red matrix limestone mechanical only rock fall talus slope, oxidizing environment