2. Understanding Blue Holes
• Whether hidden deep in the forests, in the
ocean just off a beach, or as main attractions
on isolated cays, the mysterious blue holes
throughout
• The Bahamas reveal much about an island’s
prehistoric geological past. Of note are
Andros’ "Blue Holes National Park" and Long
Island’s "Dean’s Blue Hole."
3. BLUE HOLES
• A blue hole is a large marine cavern or sinkhole, which is
open to the surface and has developed in a bank or island
composed of a carbonate bedrock (limestone or coral reef).
Blue holes typically contain tidally influenced water of fresh,
marine, or mixed chemistry. They extend below sea level for
most of their depth and may provide access to submerged
cave passages.
• Well-known examples can be found in South China
Sea (Dragon Hole), Belize (Great Blue Hole), the Bahamas
(Dean's Blue Hole), Guam, Australia (in the Great Barrier
Reef), and Egypt (in the Red Sea).
• Blue holes are distinguished from cenotes in that the latter
are inland voids usually containing fresh groundwater rather
than seawater.
6. FORMATION
• Blue holes formed during past ice ages, when sea level was as low as 100–
120 metres (330–390 ft) lower than at present.
• At those times, these formations were targets of the same erosion from
rain and chemical weathering common in all limestone rich terrains; this
ended once they were submerged at the end of the ice age.
• Most blue holes contain freshwater and saltwater. The halocline is the
point in these blue holes where the freshwater meets the saltwater and
where a corrosive reaction takes place that eats away at the rock.
• Over time this can create side passages, or horizontal "arms", that extend
from the vertical cave.
• These side passages can be quite long; e.g., over 600 metres (2,000 ft) in
the case of the Sawmill Sink in the Bahamas.
7. BLUE HOLES IN THE BAHAMAS
Deans Blue Hole Waitling's Blue Hole (San Sal)
10. ABACO BLUE HOLES
• Paleontologist Gary Morgan took up residence
in the Abacos to study the remains of
prehistoric creatures found in the depths of
one such Blue Hole called the Sawmill
Sink located in south Abaco. He is assisted by
diver Brian Kaluk and project coordinator
Nancy Albury. W.
11.
12. ABACO BLUE HOLES
• Marc Laukien produced a short movie, a journey
to "The Crystal Caves of Abaco", it's linked
below. It's mesmerizingly beautiful and in Hi Def.
2012 saw almost frenzied activity by scientists
hile under exploration the area is off limits to the
publicbecause it was determined that the deep
microbial waters in blue holes could be similar to
those on the outer planets and moons of our
solar system. Want to know more, Google "Abaco
blue holes similarity planets" and stay tuned.
14. • Richard Franz (left), a University of Florida herpetologist,
and David Steadman, a UF ornithologist, view a crocodile
skull and tortoise shell at the Florida Museum of Natural
History on the UF campus on Nov. 27, 2007.
• The first entire fossilized skeletons of a tortoise and a
crocodile found anywhere in the West Indies were
uncovered in a kind of sinkhole called a blue hole on Great
Abaco Island in the Bahamas, along with bones of a lizard,
snakes, bats and 25 species of birds, as well as abundant
fossils of plants, Steadman says. Radiocarbon analyses date
the bones at between 1,000 and 4,200 years old, with the
youngest fossil being that of a human tibia, he says.
15. The Sawmill Sink
• The oxygen-free conditions of blue holes,
however, are not an impedimentto all
lifeforms. The Sawmill Sink, for example, is
home to thriving anaerobic bacterial colonies
as well as quite a number of fossils perfectly
preserved by the anoxic waters.
17. • Long before tourists arrived in the Bahamas,
ancient visitors took up residence in this
archipelago off Florida's coast and left remains
offering stark evidence that the arrival of
humans can permanently change -- and
eliminate -- life on what had been isolated
islands, says a University of Florida researcher.
19. Fossils
• The first entire fossilized skeletons of a tortoise and a
crocodile found anywhere in the West Indies were
uncovered from Sawmill Sink on Great Abaco Island in
the Bahamas, along with bones of a lizard, snakes, bats
and 25 species of birds, as well as abundant plant
fossils.
• Radiocarbon analyses date the bones at between 1,000
and 4,200 years old with the youngest fossil being that
of a human tibia, he said.
• The fossils are the best preserved of any ever found in
the Bahamas because of their unusual location in the
deep saltwater layer of the sinkhole that contains no
oxygen, which normally would feed the bacteria and
fungi that cause bones to decay, Steadman said.
21. Brian Kakuk
• Expert diver Brian Kakuk and other skilled
scuba divers retrieved the fossils from various
places along the floor and walls of the blue
hole, which contains salt water covered by a
layer of freshwater.
26. SAWMILL SINK
• So far, divers found fossils of various animals
including tortoises, crocodiles, bats, owls, and
beetles from thousandsof years ago in Sawmill
Sink.
• Human skeletons,possibly of Lucayan people, were
also found.
• Since Dragon Hole was only recently discovered, its
bottom might also prove to hold clues to what life
was like thousands of years ago.
29. DRAGON HOLE
• “Blue holes” are a haven for both deep divers and
researchers, though for different reasons. For a
deep diver, it would mean an adventure and an
experience like no other; for a scientist, its an
insight into the past as well as the future.
• Blue holes are very deep and with no oxygen or
light, and they possess one of the harshest
environments that could exist on Earth.
• Two years ago, Chinese researchers discovered
the deepest of blue holes ever found so far—
Dragon Hole. Apart from a topographic survey, it
is as yet unexplored and unventured.
32. Questions
1.Why do you think Cynobateria is found in Blue
Holes?
2.What adaptation might an organism have that
exist at the bottom of the blue hole
3. What are stalactite and stalagmites?
4. Name two fossil discovered based on the Video
5. What problems might arise as
6. List 3 types of gear required to survived in blue
holes
