A blue hole is a submarine cave or sinkhole. They are also called vertical caves. There are many different Blue Holes located around the world, such as in the Bahamas and in Belize.
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 335 metres (1,100 ft)—is Tamaulipas, Mexico's Zacatón. The next deepest blue hole is Dean's Blue Hole at 202 metres (663 ft), located in a bay west of Clarence Town on Long Island, Bahamas. Other blue holes are about half that deep at around 100–120 metres (330–390 ft).
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.
Occurrence
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
References
External links
- Bahamas Blue Holes Guide
- Bahamas Introduction
- The Blue Holes Foundation
- Belize Audubon Society
- What's a Blue Hole? Explanation at the Bahamas Caves Research Foundation
es:Agujero azul fa:گودال آبی fr:Trou bleu (géologie) ja:ブルーホール pl:Blue Hole (Belize) ru:Голубая дыра sv:Blått hål id:Blue hole
