Origin of Shell Beaches, Padre Island, Texas

Abstract

ABSTRACT Central Padre Island, Texas is the site of a convergence of littoral drift which causes shell and sand from the entire coast to accumulate in the convergence area. Shell material is then concentrated on the beach by aeolian deflation of finer grained terrigenous sand which blows inland to contribute to the extensive infilling of Laguna Madre by wind-tidal flats, and perhaps ultimately to contribute to the aeolian sand plain of the mainland. Ancient shell beaches of the Pleistocene (?) Ingleside Complex of the mainland shore of Laguna Madre bear great similarity to the modern shell beaches of Padre Island suggesting that the general coastal configuration and wind patterns were similar to modern patterns at the time of their formation. It must be concluded that some large carbonate accumulations can occur solely as the result of a sorting process in an area of great terrigenous sediment supply.