Anomalous Response of Beaches to Hurricane Waves in a Low-Energy Environment, Northeast Gulf of Mexico, U. S. A.

Abstract

Submarine sandbars were deposited on the post-storm subaerial beach at Carrabelle Beach, Florida, by Hurricanes Elena and Kate in 1985. These bars contained stratification similar to swash bars and berms, as well as an unusual stratification consisting of interlayered beds and heavy-mineral laminae, which were slightly convex upward. Based on their internal morphology and location above the high-water line, these bars appear to be a relatively unknown type, the stranded bar. Field relationships and grain-size distributions have been examined in order to identify the principal sedimentation mode during deposition. These data support an origin by grain settling from suspension as storm wave energy decreased, but nearshore water levels remained elevated. The sediment pool comprising the bars was progressively sorted during the two hurricanes, which occurred within ten weeks of each other.