Blue hole

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.

Formation

Blue holes formed during past ice ages, when sea level was as much as 100-120 meters 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.

The deepest blue hole in the world is Dean's Blue Hole at 663ft. The next deepest holes are only around 350-400 feet deep.

ee also

*Karst topography
*Cenote
*Blue Hole (Red Sea), a famous diving spot at the coast of the Sinai peninsula

References

*PDF| [http://www.blueholes.org/pubpdf/symposia.pdf 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)] |652 KiB

External links

* [http://www.tamug.edu/cavebiology/Bahamas/BahamaIntro.html Bahamas Introduction]
* [http://www.blueholes.org/about.html The Blue Holes Foundation]
* [http://www.bahamascaves.com/blueholes.html What's a Blue Hole?] Explanation at the Bahamas Caves Research Foundation