Desert environment

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  • Hot desert environment
    • Wadi (desert stream channels/flash flood) conglomerates
      • Steep gradient and intensity of rainfall gives the streams high energy so they can transport coarse grained fragments. Deposition is rapid, leaving poorly sorted conglomerate (angular grains). Grains may have a red coating of oxidised iron minerals.
    • Desert sandstone
      • High energy winds and are affected by attrition. They are well sorted and rounded. "Millet seed sand". The grains are coated with oxidised iron minerals so that they have a red colour. Large scale cross bedding (metres - deposited in large dunes). The dunes move in the direction of prevailing winds. Sand is blown up the stoss and down the lee side (preserved face to make the cross bedding).
    • Playa lake. Hot deserts contain temporary playa lakes which may contain ions. When the water evaporates in the hot sun, the dissolved ions form evaporites. Fine grained mudstone is deposited from suspension.

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