ABSTRACT

More than 200 sand samples have been analyzed for roundness values, using roundness as curvature or roughness of surface. These have shown a consistent difference between beach and dune roundness for the same area. Because the roundness value changes at the boundary between the beach and the dunes, the difference appears to be due to selective sorting by the wind. Application of the roundness characteristic has been made to a series of borings in the barrier islands along the Texas and Louisiana coasts as an aid in determining which of the sand formations represent dunes. Dune material has been found in scattered samples from these borings down to depths of 44 feet. A series of samples taken from so-called "beach ridges" of the Texas coast have also been analyzed for roundness and hav been found to represent dune sands, showing they are eolian rather than water-laid, although their linearity suggests dunes inside of a prograding shoreline.