AU
  
You are currently viewing the Australia version of the site.
Would you like to switch to your local site?
3 MIN READ TIME

EXPLORING BLUE HOLES

The remains of crocodiles, bats and even humans have been found in these openings in the ocean floor WORDS RICHARD EDWARDS

There’s no rule that says the great wonders of the natural world have to be on dry land. Described by legendary underwater explorer Jacques Cousteau as one of the ten best diving sites on the planet, the Great Blue Hole, situated off the coast of Belize in Central America, is believed to be the world’s largest submarine sinkhole. Some 300 metres wide and 125 metres deep, the UNESCO World Heritage Site is a near-perfect circular formation where the seafloor drops sharply away from the surrounding shallows of the Lighthouse Reef atoll.

The warm waters are a beautiful, clear blue. But it wasn’t just the scenery that got Cousteau excited when he took his ship, the Calypso, there in 1971. The Great Blue Hole is also a paradise for geologists, who can marvel at its unusual rock formations and intriguing history. This hole in the ground was formed in drier times. In past ice ages, the sea level was 100 to 120 metres lower than it is now, and so the area around the Great Blue Hole would have been dry land. Cave systems formed in the limestone, and when the ceiling of one cave collapsed as a result of water erosion, a sinkhole formed. It was submerged when the ice melted and the sea rose to its current level.

The presence of stalactites provides evidence of this formation’s past, as they cannot form underwater. Some are five degrees from vertical and show a consistent orientation, indicating that the underlying rock has tilted at some point. Fossils found in blue holes can also provide clues about their past. At Sawmill Sink on Great Abaco Island in the Bahamas, skeletons of a tortoise and a crocodile – along with the bones of a lizard, snakes, bats and over 25 species of birds – were found by University of Florida researchers. A human tibia was also recovered. The fossils are the best preserved of any ever found in the Bahamas thanks to their location in a deep layer of the sinkhole with little oxygen. Oxygen would normally feed the bacteria and fungi that cause bones to decay.

Unlock this article and much more with
You can enjoy:
Enjoy this edition in full
Instant access to 600+ titles
Thousands of back issues
No contract or commitment
Try for $1.48
SUBSCRIBE NOW
30 day trial, then just $14.99 / month. Cancel anytime. New subscribers only.


Learn more
Pocketmags Plus
Pocketmags Plus

This article is from...


View Issues
How It Works
Issue 196
VIEW IN STORE

Other Articles in this Issue


WELCOME
WELCOME
Issue 196
REGULARS
Running on water
© Alamy Meet the common basilisk, also known
Harnessing solar energy
© Alamy This is one of the largest
Ariane 6 in the air
© ESA -S. Corvaja On 9 July 2024,
Eggshell science
© Shutterstock The bone-like lattice structure shown in
Nuking an asteroid could save Earth from destruction
SPACE
A simple trick could lower city temperatures by two degrees Celsius
Summer temperatures in London are predicted to get
ARCHAEOLOGY
2,700-YEAR-OLD SHIELDS AND A HELME T FROM AN ANCIENT KINGDOM UNEARTHED
1,700-year-old ‘barbarian’ burial discovered in Germany
ARCHAEOLOGY
ASTRONOMERS CAPTURE THE MOST DE TAILED MAP OF THE MILKY WAY
A selection of regions of the Milky Way
Japan will start building the first ‘zeta-class’ supercomputer in 2025
Japan has announced plans to start constructing the
TECHNOLOGY
CHINA’S ENORMOUS RADIO TELESCOPE IS GET TING EVEN BIGGER
Creepy ‘biotwang’ noises from the world’s deepest trench have finally been explained
A Bryde’s whale lunging through a school of
Aweird river may have made Mount Everest taller
A‘weird’ river in the Himalayas may have pushed
Pollen allergies drove woolly mammoths to extinction
ANIMALS
First-ever observation of ‘spooky action’ between quarks
Physicists at the world’s largest atom smasher have
JUPITER-BOUND PROBE SNAPS A PHOTO OF EARTH
Earth and the Moon as seen by the
PINBALL MACHINE ADVENT CALENDAR
£24.99 (APPROX. $33) BUILDYOUROWNKITS.COM
STEM SCIENCE ADVENT CALENDAR
£29.99 / $39.95 THAMESANDKOSMOS.COM
EXIT ADVENT CALENDAR: THE SILENT STORM
£40 / 49.95 THAMESANDKOSMOS.COM
RETRO RADIO ADVENT CALENDAR
£20 / $32 EIGHT-INNOVATION.COM
GROW YOUR OWN ADVENT CALENDAR
£34.99 (APPROX. $45.90) TREESBEESANDSEEDS.COM
JURASSIC WORLD MINIS ADVENT CALENDAR
£35.99 / $34.99 MATTEL.COM
Amazing answers to your curious questions
What is the world’s tallest waterfall? The two
THE LIBRARY
The latest book releases for curious minds
Sp ot the dif ference
See if you can find all six changes between the images below
HOW TO…
Practical projects to try at home
INBOX
Speak your mind
BIOLUMINESCENT LIFE
Dear HIW, Why do deep-sea creatures generate their own light in such dark environments? Does it not make them more vulnerable to predators?
SNAPPING PLANTS
Dear HIW, How do plants like the Venus flytrap react to the movement of flies if they don’t have a nervous system?
ANT EFFICIENCY
Dear HIW, Do ants give themselves roles to keep them carrying food in organised lines?
BAREFOOT BENEFITS
Dear HIW, If you walked everywhere barefoot, would your feet be tougher and more useful?
SPECIAL
FINDING THE DINO-KILLING ASTEROID
Hurtling for billions of miles across the Solar System, a gigantic chunk of rock zipped past the planets until it collided with ours. But where did it come from, and how did it change the course of Earth’s history forever?
INITIATING AN IMPACT WINTER
How an asteroid hitting Earth caused countless animals to perish
HISTORY
WHO WAS THE FIRST HUMAN?
50 years ago, Lucy, the famous fossil and most complete skeleton of the species Australopithecus afarensis, was discovered, filling in gaps in human history
SKELETAL FINDINGS
What does each fossilised body part tell scientists about Lucy’s species?
ANCESTOR EVOLUTION
How Australopithecus afarensis became Homo sapiens
LUCY’S DEMISE
Research that took place in 2016 – 42
FINDING LUCY
How we have learned from Lucy in the 50 years since her remains were uncovered
EXCAVATION IN ETHIOPIA
How did Lucy’s environment conceal and preserve her?
MAKING FACES
Reconstructing a digital image of Lucy’s face is
GLADIATOR II MOVIE MYTHS BUSTED
We sort fact from fiction in Ridley Scott’s upcoming Roman epic sequel
PUTTING ON A NAUMACHIA
Inside the arena that brought sea onto land to host staged naval battles
TRANSPORT
THE WORLD’S FASTEST ELECTRIC RACE CAR
Formula E cars are the most powerful and efficient electric racing cars ever made. We jump into the title-winning Jaguar I-Type 6 to find out what makes these racers tick
LEADING THE CHARGE TO VICTORY
We’re in the cockpit with James Barclay, Jaguar TCS Racing team principal
LIGHTNING-FAST ELECTRIC RACE CAR
A Formula E car like the Jaguar I-Type 6 is packed with incredible technology
ENVIRONMENT
HOW HIBERN AT ION WORKS
Winter can bring additional survival challenges to the wild, so some animals have evolved strategies that enable them to avoid these colder, leaner months altogether
WHAT IS A SWIM BL ADDER?
Rising and sinking through water would be impossible for fish without this inflating organ
TECHNOLOGY
LASER WARFARE
From dazzling defences to quick communication, these amplified light beams have multiple applications in the military
POWER-GENERATING BUOYS
How wave energy converters produce clean power from the ocean
HOW FIXED SPEED CAMERAS WORK
Why there’s no escaping the flash of a speed camera when you break the speed limit
SPACE
HOW TO RUN A SPACE STATION
The International Space Station has been in orbit so long it’s easy to take it for granted, but keeping it up and running isn’t a simple business
SPACE EXPERIMENTS
1 ALPHA MAGNETIC SPECTROMETER LAUNCH: 16 MAY 2011
SPACEWALK HARDWARE
A look at some of the tools and safety equipment astronauts need on an EVA
SCIENCE
EXPLORING THE HUMAN ECOSYSTEM
Our bodies are covered and filled with microbes, and we’re only just beginning to understand how vital they are in keeping us alive
MICROBE TREATMENTS
How to make that good bacteria work even harder for you
WHAT IS G-FORCE?
The faster you move, the more of this stomach-churning force you feel
TWINS EXPL AINED
Why do people have multiple babies in a single pregnancy?
WHAT IS THE BLOOD-BRAIN BARRIER?
How cell-lined blood vessels in the brain control what enters this organ
Chat
X
Pocketmags Support