Blue Holes of Bahamas: Figure 2. Dolines and vadose shafts produced during sea-level lowstands are drowned by sea-level rise to produce blue holes (A). Phreatic voids produced deep in the platform, possibly within the freshwater lens during sea-level lowstands, form blue holes when the collapse reaches the surface, and sea-level rises (B). Fracture of the steep bank margins of the Bahamas creates voids that become blue holes (C).

doi:10.4324/9780203483855-69

Chapter

Blue Holes of Bahamas: Figure 2. Dolines and vadose shafts produced during sea-level lowstands are drowned by sea-level rise to produce blue holes (A). Phreatic voids produced deep in the platform, possibly within the freshwater lens during sea-level lowstands, form blue holes when the collapse reaches the surface, and sea-level rises (B). Fracture of the steep bank margins of the Bahamas creates voids that become blue holes (C).

Chapter

ABSTRACT

South Andros, and Grand Bahama islands in the northwestern Bahamas, blue holes are found on islands all the way to Great Inagua Island at the southeastern end of the archipelago. In the northwestern Bahamas, blue holes with depths in the 100-125 m range are common, and it was thought that their depth was limited by the position of the lowest glacial sea-level lowstand, which was 125 m below present sea-level. However, exploratory wells commonly intersect voids below that depth, and Dean’s Blue Hole on Long Island in the southeastern Bahamas was found to be over 200 m deep, ending in a large chamber. Blue holes commonly lead into major horizontal cave systems, such as Lucayan Caverns (9184 m long) on Grand Bahama Island, and Conch Blue Hole (1153 m long) on North Andros Island.