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Tidal Sands of the Bahamian
Archipelago
Eugene C. Rankey and Stacy Lynn Reeder
Abstract
Tidal sands consisting entirely of carbonate sediments are ubiquitous in the
Bahamian archipelago. These sands include a diversity of sediment types, including
ooids, peloids, and skeletal fragments. Sands transported by tides, waves, and
currents create barforms in tidal sand complexes with a range of shapes and sizes.
These features are shaped by, and in turn modify, tidal currents that move on and
off the shallow platforms; waves and wave-driven currents play a subordinate but
locally important role in their genesis and architecture. Collectively, barforms
make up shallow shoal complexes. These shoal complexes are focused in areas
with elevated tidal currents (locally in excess of 200 cm/s) near platform margins,
and can exceed 10 km in width. The diversity of barforms and shoal morphology
evident in Holocene examples is refl ected in the stratigraphic record of numerous
ancient tidal sand shoals, with preservation favored by the early cementation
ubiquitous in these carbonate systems.
20.1
Introduction
geologists not only because they occur in tropical
waters, but also because they form modern analogs
for carbonate successions throughout the geologic
record from Archean onward. Carbonate strata form
prolifi c reservoirs that collectively host more than
50% of the world's hydrocarbons and much of its
groundwater; many of the largest carbonate reservoirs
are in tidal sands, including oolitic units (e.g., Harris
and Weber 2006 ) .
The objective for this chapter is to provide an
overview summary of aspects of carbonate tidal sand
shoals in the Bahamas. The purpose is not to explore
any one shoal in detail, but rather it aims to provide
a broad overview of sediments, bars, shoals, their
geologic history, and aspects of their dynamics. As
such, it is intended to be a synthesis; for details of
data or methods, refer to the primary literature cited
throughout.
Tidal sands of the Bahamian Archipelago have been
the focus of study for over 100 years (Agassiz 1896 ;
Rich 1948 ; Illing 1954 ; Newell et al. 1960 ; Purdy
1961 ; Ball 1967 ; Hine 1977 ; Gonzalez and Eberli
1997 ). These sands have attracted the attention of
 
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