Great Blue Hole

The Great Blue Hole is a giant submarine sinkhole off the coast of Belize. It lies near the center of Lighthouse Reef, a small atoll 70 km (43 mi) from the mainland and Belize City. The hole is circular in shape, over 300 m (984 ft) across and 124 m (407 ft) deep. It was formed during several episodes of quaternary glaciation when sea levels were much lower. Analysis of stalactites found in the Great Blue Hole shows that formation took place 153,000; 66,000; 60,000; and 15,000 years ago. As the ocean began to rise again, the cave was flooded. The Great Blue Hole is a part of the larger Belize Barrier Reef Reserve System, a World Heritage Site of the United Nations Educational, Scientific and Cultural Organization (UNESCO).

Exploration and name

This site was made famous by Jacques Cousteau, who declared it one of the top ten scuba diving sites in the world. In 1971 he brought his ship, the Calypso, to the hole to chart its depths. Investigations by this expedition confirmed the hole's origin as typical karst limestone formations, formed before rises in sea level in at least four stages, leaving ledges at depths of 21 m (69 ft), 49 m (161 ft), and 91 m (299 ft). Stalactites were retrieved from submerged caves, confirming their previous formation above sea level. Some of these stalactites were also off-vertical by 5˚ in a consistent orientation, indicating that there had also been some past geological shift and tilting of the underlying plateau, followed by a long period in the current plane.

Blue hole

A blue hole is a large marine cavern or sinkhole, which is open to the surface and has developed in a bank or island composed of a carbonate bedrock (limestone or coral reef). Blue holes typically contain tidally-influenced water of fresh, marine, or mixed chemistry. They extend below sea level for most of their depth and may provide access to submerged cave passages. Well-known examples can be found in Belize, the Bahamas, Guam, Australia (in the Great Barrier Reef), and Egypt (in the Red Sea).

Blue holes are distinguished from cenotes in that the latter are inland voids usually containing fresh groundwater rather than seawater.

Description

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 deep blue color is caused by the high transparency of water and bright white carbonate sand. Blue light is the most enduring part of the spectrum; other parts of the spectrum—red, yellow, and finally green—are absorbed during their path through water, but blue light manages to reach the white sand and return upon reflection.

Blue Hole (New Jersey)

The Blue Hole is located in the Pinelands of Monroe Township, Gloucester County, New Jersey and Winslow Township, Camden County, New Jersey. It is a clear blue body of water situated in the middle of a dense forest, with many similar such lakes in its immediate vicinity. The water has warm and cold spots, averaging 58 to 60 degrees Fahrenheit. The color is very unusual, as most lakes and ponds in the area are brownish due to large deposits of bog iron and the presence of tannic acid. The Blue Hole is circular and about 70 feet (21 m) across. In the 1930s, the Blue Hole was a popular party and swimming spot. A wooden footbridge over the Great Egg Harbor River that once made the Hole easily accessible was wiped out by a storm in the 1960s; now it can only be reached on foot.

A number of legends exist: that it is bottomless with powerful currents, that the water is freezing cold year-round, and that the Jersey Devil is active in the area.

After people became afraid of it, the blue hole was largely abandoned. Perhaps farmers and families in the area warned children against going to the Blue Hole because the Jersey Devil lived there, and it would hurt or steal them. Locals still go to the area and use it as a party spot. There are many other 'blue holes' in the immediate vicinity, as well as quicksand and other seasonal ponds and lakes that form from springs seeping from high water table levels.

Blue hole (disambiguation)

The term blue hole usually refers to a submarine cave or sinkhole, but may also refer to:

Water-filled holes

Other