ABSTRACT

Bermuda consists of a small group of islands situated atop a volcanic seamount in the Northwest Atlantic.  The islands themselves are composed of marine and eolian, Pleistocene and Recent limestone completely capping the volcanic pedestal.  Three types of submarine limestone cave morphology have so far been identified in Bermuda, with a fourth type suspected.  The first type is reef caves which form at the base of the platform's fringing coral reefs in 10-20 m water depths.  These caves consist of cavities and roofed fissures within the reef itself.  A second type of cave occurs inland and is characterized by fissure entrances and large collapse chambers, both above and below sea level.  This type of cave is primarily found on the strip of land between Harrington Sound and Castle Harbour.  The third type consists of long, nearly level, anastomosing passages at depths of 18 m connecting Harrington Sound with the North Shore.  During glacial periods of low sea level, these caves probably served to transport runoff waters along the surface of the water table from the then enclosed Harrington Sound to outside of the north fringing reefs.  A related type of cave may connect both Harrington Sound and Castle Harbour with the South Shore.  Since the south reefs are only 1 km distant from these two inshore basins, while the north reefs are 15 km, caves following the water table to beyond the south reefs would be expected to be large, single, steeply dipping linear passages.


 

Thomas M. Iliffe, Department of Marine Biology, Texas A&M University at Galveston, P.O. Box 1675, Galveston, Texas 77553, USA.
E-mail: iliffet@tamug.edu

Keywords:  Bermuda; submarine cave; Harrington Sound; Castle Harbour.