File:Lighthouse Cave - main chamber (San Salvador Island, Bahamas) 12 (16326937652).jpg
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DescriptionLighthouse Cave - main chamber (San Salvador Island, Bahamas) 12 (16326937652).jpg |
Main chamber of Lighthouse Cave (looking ~southeast toward the Aeolian Chamber), near Dixon Hill Lighthouse, northeastern San Salvador Island, eastern Bahamas. (photo taken by Mark Peter) Lighthouse Cave is hosted in eolian, cross-bedded, aragonitic calcarenite limestones of the Owl’s Hole Formation (Middle Pleistocene). This cave is a classic example of a flank margin cave. They form at the flanks of carbonate islands and at the margins of fresh-groundwater lenses. As such, flank margin caves are phreatic features. In the vinicity of the seawater-freshwater mixing zone (halocline) of a groundwater lens (see diagram - www.carbonatecreek.com/caves/images/carbisland.gif), relatively rapid dissolution of limestone occurs due to the high aggressivity of the water. Limestone dissolution at Lighthouse Cave occurred during the MIS 5e highstand (early Late Pleistocene ~119-131 ka). Flank margin caves have no surface entrances. Access to flank margin caves occurs only after surficial erosion intercepts chambers or passages. Lighthouse Cave was drained of water during the long-duration lowstand accompanying the Wisconsinan Glaciation (middle & late Late Pleistocene). Today, the lowest levels of Lighthouse Cave are partially flooded. Tidal fluctuations indicate connectivity with the ocean. Dripstone speleothem (stalactites, stalagmites, columns) composed of travertine is common at Lighthouse Cave. Published information indicates that speleothem formation has occurred since about 71 ka. Bell holes, bell pits, and sawtooth draperies are also present. |
Date | |
Source | Lighthouse Cave - main chamber (San Salvador Island, Bahamas) 12 |
Author | James St. John |
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This image was originally posted to Flickr by jsj1771 at https://www.flickr.com/photos/47445767@N05/16326937652. It was reviewed on 2 March 2015 by FlickreviewR and was confirmed to be licensed under the terms of the cc-by-2.0. |
2 March 2015
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Date and time of data generation | 10:43, 23 March 2011 |
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File change date and time | 01:31, 20 January 2015 |
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Exif version | 2.21 |
Date and time of digitizing | 10:43, 23 March 2011 |
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Date metadata was last modified | 20:31, 19 January 2015 |
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