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the precipitation increased and the great rivers carried a lot of sediments to their lower parts. Besides, small plants, bushes and also trees reappeared, while man began te have more and more influence on the landscape. In the region corresponding to the Ooijpolder, due to frequent floodings, sand and sablon (mixture of clay and sand) were deposited on the river banks, while at greater distance from the summer bedding where the stream was slower, sludge sank to form clay soil. This transition in the composition of the soil can still be found at present time: sand and gravel (among which little pabbles carried from the Alps) along the Waal and thick layers of heavy clay at the foot of the glacial till, with the best part for agriculture in the fertile middle ribbon.
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