These plains are made up of alluvial sediment and volcanic flows, and contain large areas of rich agricultural soils.
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The water then gradually deposits the sediment as it runs, creating an alluvial plain.
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Workers collected gold by washing the nuggets out of sediment in alluvial deposits, or by the more labor-intensive process of grinding and washing gold-bearing quartzite.
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Alluvial plain, formed over a long period of time by a river depositing sediment on its floodplain or bed which becomes alluvial soil.
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The flood threatened area of the Netherlands is essentially an alluvial plain, built up from sediment left by thousands of years of flooding by rivers and sea.
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The morphology of an alluvial river reach is controlled by a combination of sediment supply, substrate composition, discharge, vegetation, and bed aggradation.
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The hydraulic engineer is concerned with the transport of sediment by the river, the interaction of the water with its alluvial boundary, and the occurrence of scour and deposition.
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This sediment has been redeposited in a wide variety of wet environments, including in alluvial fans, meandering channels, deltas, lakes, and perhaps even oceans.