Geology Reference
In-Depth Information
These winds are strong throughout the year, but the
speeds peak during the winter where they can blow
steadily at speeds greater than 10 m/s. Several cold
fronts affect this area annually (Roberts et al.
1982,
1992
). These fronts pass over the archipelago from the
northwest to the southeast, bringing winds that shift
from south to west (frequently the strongest) to north
or northeast before returning to the dominant easterly
direction. Tropical cyclones are common in this part
of the Caribbean from June through November, so
hurricane strength winds can be expected during these
months. Neumann et al. (
1978
) estimated that, on aver-
age, hurricanes struck the southern Bahamas/Caicos
once every 5 years, and Florida and the northern
Bahamas once every 7 years.
Despite the generally high wind speeds of the
Bahamian Archipelago, the waves have little effect on
most platform interiors. Large, open water swells decrease
in size due to shoaling caused by the steep platform
slopes and shallower waters of the margins and platform
interiors or breaking either along the reef-rimmed margins
20.2
Boundary Conditions: Tides,
Waves, and Saturation State
The Bahamian Archipelago, located in the tropical to
sub-tropical Caribbean (~20-28°N latitude, ~69-79°W
longitude), includes a series of fl at-topped, isolated
carbonate platforms separated by deeper water pas-
sages (Fig.
20.1
). It is bounded by the Atlantic Ocean
to the north and east, the Old Bahama Channel to the
south, and the Straits of Florida to the west. Water
depths on the tops of the larger platforms (Little
Bahama Bank, Great Bahama Bank, Crooked-Acklins
Platform, Caicos Platform) are less than 20 m, and
many areas are less than 10 m. At their margins, these
shallow-topped platforms slope precipitously to depths
of 500 m (Straits of Florida) or more (Tongue of the
Ocean, Northwest Providence Channel, Exuma Sound,
Crooked Island Passage).
This area is affected largely by the easterly trade
winds, which affect the latitudes between 4° and 30°.
Fig. 20.1
Locations of study areas. Regional bathymetric set-
ting in the eastern Caribbean, illustrating location of major shoal
complexes (
red blobs
) including those discussed in the text and
labelled: Mackie Shoal (
M.S.
), Cat Cays (
C.C.
), Joulter Cays
(
J.C.
), Green Cay (
G.C.
), Tongue of the Ocean (
TOTO
),
Ambergris Cay (
Amb. Cay
). Platforms include: Great Bahama
Bank (
GBB
), Little Bahama Bank (
LBB
), Crooked-Acklins
Platform (
CAP
), and Caicos Platform (
TCI
); Bathymetric data
from General Bathymetric Chart of the Oceans (GEBCO) of the
Intergovernmental Oceanographic Commission (IOC) and the
International Hydrographic Organization (IHO)
