Origin of shell beaches, Padre Island, Texas




Watson, Richard Lee, 1943-

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Shell-rich beaches on central Padre Island correlate with a convergence of longshore drift. Wind data collected at Corpus Christi from 1951 to 1960 and sedimentation at inlets to the north and to the south of the study area both suggest a similar convergence of longshore drift. Local highs in shell content of beach sands correspond to areas of high and continuous foredunes, whereas the position of lows correspond with small dunes and numerous hurricane channels. Waves which approach the beach obliquely, sort pelecypod valves such that if the waves approach from the right as the observer faces the sea, there is an abundance of right valves at the top of the foreshore and an abundance of left valves in the shell step at the base of the foreshore. If the waves approach obliquely from the left, the opposite sorting occurs