6: Sediments and Sedimentary Rocks (Exercises)
- Page ID
- 2045
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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 |