Hurricane Betsy in the Florida-Bahama Area: Geologic Effects and Comparison with Hurricane Donna

Abstract

Within a 5-year period two violent tropical storms, Hurricanes Donna and Betsy, passed over the Florida Keys. Although these hurricanes were of comparable size and intensity, their geologic effects differed. Both hurricanes caused extensive damage to the outer reefs, although Betsy acted essentially on a fauna from which Donna had removed the weaker elements. Large-scale movement of sand on White Bank which resulted from Hurricane Donna did not occur during Betsy. In Florida Bay, supratidal sedimentation on the islands and mainland was extensive during Donna, but virtually absent during Betsy. An exception to this was the deposition of spillover lobes of skeletal sand landward of the beach on Cape Sable. Unlike Donna, Hurricane Betsy passed over the northwest portion of the Great Bahama Bank. Large spillover lobes of oölitic sand were eroded back as much as 140 feet. Sedimentation on the Andros tidal flats was restricted to vegetated highs, even though the entire tidal flat complex was inundated by as much as 9 feet of water.