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-85°
-80°
-75°
-70°
-65°
35°
Atlantic Ocean
(a)
Gulf of
Mexico
(b)
Bahamas
25°
Blowholes
Great Pedro Point
Boulder piles
0
5
10 km
(a)
20°
Grand Cayman
Island
Leeward
Netherlands
Antilles
Jamaica
15°
Caribbean
Sea
(c)
Great Abaco
(b)
10°
Eleuthera
(c)
Chevron
ridges
Aruba
Curaçao
Bonaire
Andros
Great Exuma
Long
0
100
200 km
0
50
100 km
Fig. 4.7
The Caribbean Region. a Grand Cayman Island, b Bahamas, c Leeward Lesser Antilles
the product of tropical cyclones (hurricanes). The first of
these examples comes from the Cayman Islands (Fig. 4.7 a).
The islands exist in a region where tsunami have played a
major role in the region historically. For example, in June
1692, a powerful tsunami devastated Port Royal on the
nearby island of Jamaica. The region is also dominated by
tropical cyclones. For example, in 1785 a tropical cyclone
destroyed every house and tree except one on the Cayman
Islands. In 1932, a hurricane with winds of 330 km h -1
generated seas that carried huge rocks weighing several
tonnes. The waves moved coral boulders 0.6-1.0 m in
diameter
of the boulders were emplaced at least 12 m above sea
level. Many of the boulders originated as giant rip-up clasts
torn from terraces formed in dolomite or from boulder
deposits at the base of sea cliffs. The terraces had solutional
weathering pinnacles and ridges with a relief of 2 m that
were planed flat. According to Eqs. ( 3.3 ) and ( 4.2 ), the
largest boulder required a storm wave 12.5 m high to move
it. The equivalent tsunami wave was only 3.1 m high. The
storm waves could only exist if water depths were more
than 16 m deep at the base of cliffs, otherwise they would
have broken. This condition occurs at only one of the
locations where boulders are found. Even here, it is doubtful
if storm waves could have maintained sufficient energy to
transport boulders more than 100-150 m inland.
A second example comes from the Bahamas (Fig. 4.7 b),
where the landscape has been created by either tsunami or
storm waves. The Bahamas offer a range of features sug-
gestive of tsunami from the Last Interglacial. Most inter-
esting are V-shaped ridges up to several kilometers in
length that have penetrated inland from the exposed
Atlantic Ocean side of the islands (Hearty et al. 1998 ). The
ridges are asymmetrical, averaging 3 km in length, with
some exceeding 10 km. They are 20-100 m wide and stand
shoreward
from
waters
less
than
15 m
deep,
constructing ramparts at shore.
Bigger boulders exist than those transported by these
storms (Jones and Hunter 1992 ). The boulders appear to be
related to a high-energy, prehistoric event dating around
1662 that moved slabs as large as 5.5 m in length, depos-
iting some in clusters up to 150 m inland. Some clusters
contain imbricated stacks of boulders, aligned in a north-
south direction, roughly at right angles to the shoreline. At
Great Pedro Point, blocks weighing up to 10 tonnes were
moved 18 m vertically and 50-60 m inland of the cliff line.
The largest boulder measures 5.5 m 9 2.8 m 9 1.5 m. All
 
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