Bimini Road - Geological Explanation

Geological Explanation

The consensus among conventional geologists and archaeologists is that the Bimini Road is a natural feature composed of beachrock that orthogonal and other joints have broken up into rectangular, subrectangular, polygonal, and irregular blocks. The geologists and anthropologists who have personally studied the Bimini Road include Eugene Shinn of the U.S. Geological Survey; Marshall McKusick. an Associate Professor of Anthropology at University of Iowa; W. Harrison of Environmental Research Associates, Virginia, Beach Virginia; Mahlon M. Ball and J. A. Gifford of the Rosenstiel School of Marine and Atmospheric Science, University of Miami; and Eric Davaud and A. Strasser of the Department of Geology and Paleontology, University of Geneva, Geneva, Switzerland. After either inspecting or studying the Bimini Road, they all concluded that it consists of naturally jointed beachrock. John A. Gifford, a professional geologist, spent a significant time studying the geology of the Bimini Islands for his University of Miami Master's thesis about the geology of the Bimini Islands. Calvert and others identified the samples that they dated from the Bimini Wall as being natural beachrock.

Detailed studies by E. Davaud and A. Strasser of Holocene limestones currently exposed on North Bimini and Joulter Cays (Bahamas) reveal the sequence of events likely responsible for creating beachrock pavements like the Bimini Road. First, a complete beach sequence of shallow subtidal, intertidal, and supratidal carbonate sediments accumulated as the shoreline of North Bimini built seaward during part of the Holocene. Once the deposition of these sediments built the North Bimini's shoreline seaward, freshwater cementation of the carbonate occurred at some depth, possibly even a meter or so below sea level, beneath the island's surface. This cementation created a band consisting of a thick primary layer of semilithified sediments and thinner discontinuous lenses and layers of similar semilithified sediments beneath it. Later, when erosion of the island's shoreline occurred, the band of semilithifed sediment was exposed within the intertidal zone and the semilithified sediments were cemented into beachrock. As the sediments underlying the eroding shoreline was eroded down to Pleistocene limestone, the beachrock broke into flat-lying, tabular, and rectangular, subrectangular, polygonal, and irregular blocks as observed for modern beaches within the Bahamas by E. Davaud and A. Strasser. Thinner layers of beachrock underlying the primary bed of beachrock were also broken up as the loose sediments enclosing them and the thicker primary bed were eroded. As the loose sediment was scoured out from under the blocks and other pieces of beachrock by so-called "scour and settling processes", they dropped downward for several meters until they rested directly on the erosion-resistant Pleistocene limestone as an erosional lag. Eugene Shinn discusses a similar, but not identical, process by which the Bimini Road could have been created.

The downward movement of large, solid objects by scour and settling processes has been documented by Jesse E. McNinch, John T. Wells, and other researchers. They concluded that large, heavy objects could sink into the sea bottom by several meters without significant lateral movement as the result of scour and settling processes if an erosion-resistant layer of sediment was not encountered. In case of the beachrock blocks composing the Bimini Road and other pieces underlying it, the erosion-resistant layer that limited how far they were dropped downward by scour and settling processes is the Pleistocene limestone on which they now rest.

Finally, pieces of thinner layers or lenses of beachrock underlying the primary bed that was broken up and dropped downward to create the Bimini Road would be trapped beneath the blocks as they also were broken up and dropped by erosion. The trapping of these fragments of beachrock beneath the blocks composing the Bimini Road, as erosion removed loose sediments and dropped them on the surface of the Pleistocene limestone, would have created the so-called "prop" and "wedge" rocks and blocks alleged to be a "second course" of "masonry". Presuming that the blocks of beachrock forming the Bimini Road originally formed at some unknown depth below sea level and have been dropped by erosion by several meters, dating the age of the Bimini Road by its relation to past sea level would be a useless technique that would produce misleading results.

Natural pavements composed of stone blocks, which often are far more rectangular and consistent in size than the blocks composing the Bimini Road, created by orthogonal and other jointing within sedimentary rocks, including beachrock, are quite common and found throughout the world. They include a popular tourist attraction, the Tessellated pavement of Eaglehawk Neck, Tasmania; jointed bedrock that has been completely misidentified as a man-made "Phoenician Fortress and Furnace" in Oklahoma; a "tiled pavement" reported from Battlement Mesa in western Colorado; the tessellated pavement of the Bouddi Peninsula near Sydney, Australia; and Arches National Park in Utah. Natural beachrock pavements that are identical to the Bimini Road have been found eroding out of the east shore of Loggerhead Key of Dry Tortugas and submerged beneath 90 meters of water at Pulley Ridge off the southwest coast of Florida.