Lighthouse Cave

Dixon Hill Lighthouse Cave

Useful Information

Location:	Dixon Hill, at the northeast end of San Salvador Island. Southeast of the Dixon Hill Lighthouse.
Open:	no restrictions. [2014]
Fee:	free. [2014]
Classification:	Karst cave
Light:	bring torch
Dimension:
Guided tours:	n/a
Photography:	Allowed
Accessibility:	Not wheelchair accessible, some climbing required
Bibliography:	John E. Mylroie, James L. Carew (1994): A Field Trip Guide Book of Lighthouse Cave, San Salvador Island, Bahamas, San Salvador, Bahamas: Bahamian Field Station. ISBN-13: 9780935909487
Address:	San Salvador Tourist Office, Tel: +1-242-331-1928, Tel: +1-242-331-1929. E-mail: E-mail:
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History

Description

Lighthouse Cave is the largest cave on the island San Salvador. It has three entrances. The Main Entrance has a drop of two meters, the cave is entered on a ladder. Although undeveloped it is rather easy to visit. Passages radiate outward from a large central chamber and end abruptly.

The floor near the Main Entrance shows forms of vadose flow, and the ceiling numerous so-called bell holes, which are small phreatic pockets. But there are no definite phreatic flow marks on the walls anywhere in the cave, so there was no turbulent phreatic flow involved in cave formation. Only little breakdown can be found, which has been disarticulated in place as a result of dissolution.

Aeolian Chamber was named after the wall rock of this part of the cave, which shows eolian sedimentary structures. The rock is Owl's Hole Formation of Middle Pleistocene age, an eolian, cross-bedded, aragonitic calcarenite limestone. Dating of stalagmites supports an upper Pleistocene age for the development of the cave.

Lighthouse Cave is one of the best known flank margin caves in the Bahamas. They form at the flanks of carbonate islands and at the margins of fresh-groundwater lenses, hence the name. In the vicinity of the seawater-freshwater mixing zone (halocline) of a groundwater lens, the dissolution of limestone happens relatively rapid due to the high aggressively of the water. Limestone dissolution at Lighthouse Cave occurred during the MIS 5e high stand.

Flank margin caves are phreatic features and have originally no surface entrances. Access is a result of surficial erosion which intercepts chambers or passages. Lighthouse Cave was drained of water during the low sea level of the Middle and Late Pleistocene. Today, the lowest levels of Lighthouse Cave are partially flooded again. The water is slightly hypersaline and the tidal range in the cave is almost one metre. The tidal fluctuations indicate connectivity with the ocean.

Many researchers visited the cave and there have been biological, geological and geochemical researches. One result of this scientific interest was the creation of the Gerace Research Center on this island.