The modern valley of the Colorado River near Columbus and Eagle Lake is incised into terraces representing depositional surfaces of early Pleistocene sediments. The terraces which normally are cut landward from the deltaic shoreline areas have been accentuated by continued Pleistocene uplift along a down-to-the-basin fault crossing the river near Eagle Lake. Extensive deposition of coarse materials in the sag downstream from the fault has steepened stream and terrace gradients in comparison with gradients above the fault. The present river is progressively moving coarse materials downstream from earlier deposits.

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