Abstract

The stoss face of a large parabolic dune at Dillon Beach, California, is being actively eroded by wind action. The result is formation of a lag deposit consisting largely of shells of Helminthoglypta arrosa (Gould), a heliciform, terrestrial gastropod. Wind velocities up to thirty miles per hour serve to orient many of these sand-filled shells with the aperture away from the prevailing wind direction. In addition, sandblasting by saltating grains produces a wedge-shaped abrasion or decortication pattern on the spire of the shell with the wedge pointing downwind. Wind-oriented gastropod shells and decortication wedges may be useful criteria for determination of paleowind directions in ancient dune deposits.

First Page Preview

First page PDF preview
You do not currently have access to this article.