Geology Reference
In-Depth Information
(a)
(b)
Fig. 5.
Newly exposed submerged beachrock 'road' on east
side of Loggerhead Key at Dry Tortugas. The 'Loggerhead
Road' was exposed by Hurricane Katrina in 2005.
Undermining of sand beneath the stones caused the rock to
subside approximately 1 m. The blocks are 1-2 m long.
Fig. 6.
A new beachrock road was recently discovered in
90 m of water at Pulley Ridge off the southwest coast of
Florida (Jarrett
et al
., 2005). The blocks are 1-2 m long. The
discovery was made in a joint investigation by University
of South Florida, US Geological Survey, and the National
Oceanic and Atmospheric Administration.
islands near tidal inlets and occur on barrier
islands all along the eastern USA, the west coast
of Florida and the northern Gulf of Mexico.
Similar rows of carbonate beachrock to those
at Pulley Ridge have been reported from the
same water depth (90 m) in the northern Gulf
of Mexico (unpublished Minerals Management
Report). It is well documented that sea level
has risen at least 100 m worldwide in the past
13-10 kyr world-wide (Fairbanks, 1989).
Sea developed geologically in a similar fashion.
In the Persian Gulf or Arabian Gulf, one can
observe that curved spits have provided natural
sheltered harbours allowing villages to be estab-
lished because of the shelter they provide. As
the spits migrate laterally along the coast and the
harbours fi ll in, villages adjacent to the shallow-
ing end of the harbour are abandoned and rebuilt
around the deepening newly forming harbour
entrance.
Similar processes are likely to have occurred
along the southern Mediterranean shore, where
the climate is arid and seawater salinity is gen-
erally elevated. In areas where the harbours were
especially important for commerce, it would
be reasonable to build structures around pre-
viously formed natural beachrock-protected
Speculation and future research possibilities
Alternative thinkers who believe the Bimini stones
are anthropogenic features often cite historic
harbours in the Mediterranean Sea as models
for what they believe occurred at Bimini during
prehistoric or 'Atlantian' times. The sand spits
and offshore barrier islands that migrate and form
harbours in the Persian Gulf may well indicate
that some ancient harbours in the Mediterranean
