Blue hole
From Wikipedia, the free encyclopedia
A blue hole is a submarine cave or sinkhole. They are also called vertical caves.
Blue holes are roughly circular, steep-walled depressions, and so named for the dramatic contrast between the dark blue, deep waters of their depths and the lighter blue of the shallows around them. Their water circulation is poor, and they are commonly anoxic below a certain depth; this environment is unfavorable for most sea life, but nonetheless can support large numbers of bacteria.
The deepest blue hole in the world - at 202 metres (663 ft) - is Dean's Blue Hole, located in a bay west of Clarence Town on Long Island, Bahamas. The next deepest holes are about half that deep at around 100–120 metres (330–390 ft).
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[edit] Formation
Blue holes formed during past ice ages, when sea level was as much as 100–120 metres (330–390 ft) lower than at present. At those times, these formations were subjected to the same chemical weathering common in all limestone-rich terrains; this ended once they were submerged at the end of the ice age.
Blue holes are typically found on shallow carbonate platforms, exemplified by the Bahama Banks, as well as on and around the Yucatán Peninsula, such as at the Great Blue Hole at Lighthouse Reef Atoll, Belize
[edit] See also
- Karst topography
- Cenote
- Blue Hole (Red Sea), a famous diving spot at the coast of the Sinai peninsula
[edit] References
- Stephanie Schwabe and James L. Carew. "Blue Holes: An Inappropriate Moniker for Scientific Discussion of Water-Filled Caves in the Bahamas" (Accessed 3/8/06)PDF (652 KiB)
[edit] External links
- Bahamas Blue Holes Guide
- Bahamas Introduction
- The Blue Holes Foundation
- What's a Blue Hole? Explanation at the Bahamas Caves Research Foundation
