In August 1968 overbank flooding of the Prairie Dog Town Fork of the Red River resulted in the deposition of a blanket of very fine to fine sand on the floodplain in Palo Duro Canyon State Park, 24 km southeast of Amarillo, Texas. Surrounding many of the trees on the floodplain, centroclinal cross strata (concentric and with dip toward a common center) were discovered in this new layer of sand. They are the result of infilling of scour holes created around the trees by swirling flood water. Where this primary sedimentary structure is discovered in ancient rocks, it will indicate a specific environment (wooded floodplain) and mechanism of deposition (receding floodwater of decreasing competency). The structure will also indicate top and bottom of strata.

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