PULLEY RIDGE: WHAT NEWLY MAPPED AREAS REVEAL ABOUT SEA-LEVEL CHANGE

Based on previous publications, Pulley Ridge is known to be a submerged barrier island located approximately 250km West of Cape Sable, Florida. The ridge trends North-Northeast in water depths ranging from 60m-110m and is approximately 32km long, 5km wide and approximately 10m tall. High resolution bathymetric imagery collected by us have been used to show many morphological similarities between Pulley Ridge and modern day “drumstick” barrier islands found off the coast of Georgia and South Carolina. This area harbors one of the deepest photosynthetic coral reefs in the Continental United States, and perhaps the World. These corals are ecologically important, as they are resistant to many of the forces detrimental to shallow water coral reefs. Reef structures may play a part in the preservation of Pulley Ridge, preventing significant reworking of what appears to be s brief still-stand of sea level rise, since the last ice age. In September 2009, multibeam bathymetry and backscatter data collected with a Kongsberg EM 3000 (300 kHz) echosounder aboard the R/V Weatherbird II confirmed the existence of a second slightly deeper ridge to the West of Pulley Ridge. This newly-mapped feature is sub-parallel and morphologically similar to Pulley Ridge, suggesting that it was formed by a similar set of processes. The deeper location suggests a sea level still-stand occurred prior to the formation of the Pulley Ridge still-stand. Preservation of details strikingly similar to modern barrier islands indicates the complex interplay between sea level changes, sediment supply, longshore transport, and biological impacts. Future analyses of recent video transects through these new data by Andrew David and others of NOAA, will be helpful in testing how similar this westward ridge is to the well-studied Pulley Ridge.