Saturday, March 29, 2014

Bahamian Blue Holes

Man O War Cay

Halocline is the zone where salt water and fresh water meet.  In a vertical column of water, fresh water will sit on top of salt water because it is less dense.  If an object falls into such an aquatic vertical column, it can remain suspended in the halocline and decompose in this suspension.  It is a paleontologist’s delight.   

Yesterday, we were on the ferry from Marsh Harbor to Man O War Cay in the Abaco Island chain in northern Bahamas when we met Nancy Albury, a paleontologist whose passion is the study of Bahamian blue holes.  We were on our way to a talk she was giving entitled, New Discoveries from Blue Holes, Caves, and Beach Sands: Are clues from our past charting our future?  Craig is a patient companion when I drag him to these kinds of events but even he was excited about this one.  The attraction: the discovery of perfectly preserved Cuban Crocodile skeletons at the bottom of the Abacos blue holes.  The Cuban Crocodile (affectionately hereby known as CC) is the one that even the scientists at the Crocodile Conservation Center in St. Augustine, Florida give a wide berth to.  CC is nasty.   It doesn’t have the more common sideways, elbows-out kind of crawl that other crocs have.  Instead, it moves more upright on its legs with its feet forward making it fast and aggressive.  Our fascination with crocs and alligators was piqued when we visited the Center a couple of years ago and to have the croc raise its head again was reason enough to catch the ferry to another island to learn more from Nancy.  She generously gave us a private audience on the ferry with her stash of bat specimens, crocodile and tortoise bones, and stories of living on and exploring these islands.

The thing is, CC doesn’t live in the Bahamas anymore.  Nor do 22 bird species whose remains were part of the 43 avian species found at the bottom of the blue holes here.  A blue hole is a deep chasm in the earth or ocean where fresh water is trapped on top of salt water.  The salt-water source is from the bottom of the hole, and is typically fed from cave systems and tunnels that lead out to and in from the ocean.  Bahamian blue holes are particularly remarkable for the clues they are providing about geological, biological, and sociological history.  The Bahamas archipelago was once high and dry, and dotted with stalactite and stalagmite column filled land caves.  Water levels here are presently 425 feet higher than they were at the peak of the last ice age.  As sea levels rose, these caves were filled with layered saline and fresh water, and perfectly protected by the halocline layer of trapped hydrogen sulfide gases.  Flora and fauna that are 1500 years old are still green as they lie suspended in the halocline.  Nancy showed us the bright blue wing of an insect that was also centuries old. 

The once terrestrial (land locked) ecosystem is frozen in time and the tricky part is getting access to it.   Nancy and her colleagues are cave divers of the extreme kind who weave in and out of the kilometers long cave systems, looking for clues in skeletal remains, coral remnants, seeds, plants, and insects.  Human remains have also been discovered and are speculated to be the now extinct Lucayans, South Americans who lived here a thousand years ago.   Nancy’s work is highlighted with superb photos at http://www.bahamascaves.com/photogallery.html.  National Geographic has also profiled Nancy's discoveries.  


We have anchored at the northern end of the Bahamas in the Abacos, joining the parade of North American cruisers heading back north.  We have been captive at Marsh Harbour for a week, until the heavy surfs at the cut entrances between the islands and the Atlantic Ocean settle down.  The secure holding of our anchor enables us to leave the boat without worry and take the local ferry across the Sea of Abacos to Man O War Cay and colonial Hope Town on Elbow Cay.  After meeting Nancy, a beach is no longer just a beach.  It is another revelation of the topography and history of these islands.


Hope Town, Elbow Cay, Abacos, Bahamas

Friday, March 7, 2014

Lessons



We are back in Black Point Harbour, on Great Guana Island in the Exumas, Bahamas.  There is one other boat here with us.  Two weeks ago, there were over 100 boats in this harbour.  Over the past two days, we have watched boats roar out of here in what our friend, Beth, calls the Black Point 500.  This is the mass nautical exodus that occurs every couple of weeks when news that a North Front bringing punchy west winds is about to blast us.   Black Point is wide open to those testy west winds.   Weather forecasters have again been sending bold typed warnings:
CLUSTERS OF STRONG CONVECTIVE SQUALLS AND THUNDERSTORMS TO 40 KNOTS…
We are staying put in Black Point.

My sister Colleen, sister-in-law Cindy, and our mom Gail, are with us.   They have watched the lovely parade of boats blasting past us on their way to somewhere else.  The other hardy boat remaining is owned by a family from Canmore, Alberta.  For those of you unfamiliar with western Canadian geography, Canmore and our home town are only a couple of hours apart, bordering the central Canadian prairies and Rocky Mountains.  Land-locked, central Alberta.  We all grew up making snowmen and sliding down icy hills on toboggans.  Canmore family and Alberta Crewed have decided that this is the place to rock through the system. 

Colleen finally voiced her bewilderment at our decision to stay.  “I’m a bit concerned.  It’s us and a boat from Canmore.  Are you sure?”  After sitting out several fronts in this area, we are confident this is our best bet.  There are very few places one can escape west winds on the Bahamas banks.  The sheltered bays become packed with scurrying boats and tend to have very strong currents.  At Big Major, Little Major passage where most are heading to, we had very long nights (see previous blog).  Here at Black Point, we have excellent holding (sand), lots of space (no kidding), and are close to a town if we want a break from the rocking and rolling.  Ida who owns the Laundromat/store/hairdresser also pointed out that the town watches out for those of us on boats.  They are ready to help if we need anything. 

Black Point has also become our home this winter.  The community’s generosity and kindness towards us foreigners continues to humble us.  When I introduced my family to our town friends, they all hugged mom.  “Mama!”, they exclaimed.  Mamas seem to be the ones in charge in Black Point.  They are revered; running many businesses, organizing churches, baking bread and ensuring supplies are brought in from Nassau for the yachties, and caring for multi-generational families.   

Walking main street



We were snorkeling along the shore near the school a couple of days ago when Mom and I popped up and were called over by a class of five year olds and their two teachers in the midst of an outdoor classroom.  They wanted to know what we were doing, and what we could see.   These children are growing up in and around the water.  I could not imagine telling them anything they didn’t know.  They therefore told us.  Watch out for rays and don’t step on them.  They have sharp tails.  There are also sharks.  “What kinds of sharks?” I asked them. “Nurse sharks!"  "Black Tip Sharks!"  "Big-ass sharks!”  Of course.  Watch out for rays and big-ass sharks.  They sang us a song about Love, blew us kisses, yelled that they loved us, and sent us back into the sea.   


Black Point is more than our haven through storms.  They haven’t given up on silly Canadians yet.

Our shoreline lesson