LIMESTONE CAVES ON ABACO: WELL WORTH LOOKING INTO…


Abaco Parrot nest (Caroline Stahala)

LIMESTONE CAVES ON ABACO: WELL WORTH LOOKING INTO…

I have written several posts in the last few months featuring Brian Kakuk’s amazing photos of the underwater caves of Abaco. These caves, mostly beneath Abaco’s pine forests, are fabulous treasures of rock and crystal. A recent post example can be seen HERE. I have also featured some of the famous Blues Holes of Abaco from time to time, for example HERE. So now it’s time to turn attention to ‘land caves’, the dry(ish) limestone holes and caverns that are dotted around Abaco, especially in the South, and bear witness to aeons of geological development through erosion.

The coppice and extensive pine forests are pitted with holes of widely varying sizes. I’m way out of my depth here, geology-wise (polite corrections invited), but this sort of landscape is I believe known as KARST. This term presumably includes Abaco’s ‘dry’ holes, the blue holes and the substantial network of underwater caverns. Small examples can readily be found in easily accessible places such as non-dense coppice. We were very surprised when we pushed our into the coppice bordering the Delphi Club guest drive and took a closer look at a hole. Although the weather was hot and dry at the time, you will see that the hole has some form of micro-climate, with damp walls and interior and wet-climate plants like small ferns and forms of what I take to be moss and algae.

ONE OF MANY LIMESTONE HOLES BESIDE THE DRIVES AT DELPHILimestone Hole, Delphi, Abaco (Keith Salvesen)

A HOLE NEAR HOLE-IN-THE -WALL – LARGER INSIDE THAN IT LOOKS 

Limestone Hole, Hole-in-the-Wall Abaco01  Limestone Hole, Hole-in-the-Wall Abaco03

THE CAVE-DWELLERS OF ABACO: THE FABULOUS PARROTS

Among the best-known special residents of Abaco are the ground-nesting parrots, gorgeous birds that I have often featured in the past – see the parrot page HERE. Not so long ago, their numbers had reduced to an unsustainable population – fewer than 1000 – that faced extinction. The creation of the National Park covering the pine forests where they breed, coupled with a vigilant and intensive conservation program, have reversed the trend. There is now a sustainable breeding population again, exceeding 3000 birds.  

The only other breeding Cuban parrot population in the Bahamas is found on Inagua, where they nest conventionally in trees. There is a very small non-breeding population on New Providence. Abaco’s cave-dwelling subspecies of the cuban parrot is unique. Here’s an insight into how they live, deep in the pine forest, during the summer breeding season, with many thanks to Caroline Stahala, the scientist who spent some 10 years researching and protecting the parrots.

PARROT NEST HOLES: VULNERABLE TO PREDATORS, PROTECTED FROM FOREST FIRESLimestone Holes & Abaco Parrots (Caroline Stahala) Limestone Holes & Abaco Parrots (Caroline Stahala)

PARROTS MAY NEST DEEP – OR SHALLOW. Limestone Holes & Abaco Parrots (Caroline Stahala)Limestone Holes & Abaco Parrots (Caroline Stahala)

THE BREEDING SEASON: NEST, EGGS, HATCHLINGS, FLEDGELINGS…Limestone Holes & Abaco Parrots 08Limestone Holes & Abaco Parrots (Caroline Stahala)Limestone Holes & Abaco Parrots (Caroline Stahala)Limestone Holes & Abaco Parrots (Caroline Stahala)

HOW BIG DO THE ‘DRY’ HOLES GET?

TBH my personal experience is somewhat limited. I believe there are large, sea-scoured caves along rocky parts of the south coast, but those are rather different from the eroded ground holes discussed here. As so often I rely on Mrs RH – far more intrepid than me – and her exploring skills. The cave shown below is right down at the far south of Abaco, at Hole-in-the-Wall, hidden in the coppice along the ‘Soldier Road’ from the T-junction (we are talking rough tracks here – very – not proper roads) towards the lighthouse. 

Soldier Road Sign, Hole-in-the-Wall Abaco

Limestone Hole, Hole-in-the-Wall Abaco15Limestone Hole, Hole-in-the-Wall Abaco16Limestone Hole, Hole-in-the-Wall Abaco06Limestone Hole, Hole-in-the-Wall Abaco13

The rock is far more colourful than you  might expectLimestone Hole, Hole-in-the-Wall Abaco09

Credits: Caroline “The Parrot Lady” Stahala; Mrs RH for investigating the last cave and taking the camera with her; RH the rest; Woody Bracey for our great day of birding at Hole-in-the-Wall and his local knowledge of the area… 

“ROCK & ROLLING WAVES”: ROCK EROSION ON ABACO


Rock Erosion Gilpin Point 3

“ROCK & ROLLING WAVES”: ROCK EROSION ON ABACO

On 26th October 2012, the ‘roof’ of the geological feature at the southern tip of Abaco known for centuries as Hole-in-the-Wall was blasted apart by Hurricane Sandy. The combination of huge waves and powerful winds proved too much for a structure that had existed since the last ice age. I posted in detail about this event last year HERE so now I will concentrate on some geological aspects.

The photo below shows the Hole a year or so before its destruction. At the left-hand end of the bridge there is a paler area underneath where limestone rock had recently fallen into the sea, suggesting an underlying instability. At close quarters there were plenty of cracks in the apparently solid structure. (I’ve no idea why I didn’t straighten the image. Let’s say… Artistic Perspective)hole-in-the-wall-abaco-ricky-johnson

This photo was taken a few days after the collapse, the first to be published of the new view. The clean white rock at either end of the ex-bridge is clearly visible. The section on the left became a new islet at the southern extremity Abaco, separated from the mainland for the first time in history. I proposed various names for it (not all serious) – Sandy Cay (or Isle) was the clear, indeed obvious, winner…

Hole-in-the-Wall Abaco- the new gap Nov 2012

This close-up of the south side of the bridge shows the detail of the rock fragmentation. Tara’s photographs are (as far as I know) the very first of the new gap and of Abaco’s new islet, predating John Haestad’s by a day.HOLE-IN-THE-WALL ABACO post Sandy 3

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We recently went to a beach near Crossing Rocks that we had never explored before (plenty of interest there for later posts). We were struck by the fragmented and pitted nature of the limestone rocks on the shoreline. We noticed some pale exposed rock surfaces, similar to those at Hole-in-the-Wall. We watched the incoming waves scouring and undercutting the rocks, leaving overhangs (see video below). Erosion is increased by the double action of the waves. The immediate area hinted that there may even have been a very small Hole at one time. On the day we were there, the sea was gentle. It’s easy to imagine how the hugely destructive force of the wind and crashing waves resulting from hurricanes such as Sandy can eventually shatter solid rock that has been gradually eroded and destabilised over centuries by wave action.Rock Erosion Gilpin Point 1 copyRock Erosion Gilpin Point 2 copy

Photo credits as shown / RH. You have Mrs RH to thank for a shorter (50 secs) video than the one I originally made (75 secs). Now I’ve redone the thing, I agree – one wave does look very like the next… 

ADDENDUM Just remembered that I took an aerial photo of HitW from the plane the other day. It’s a phone photo through BahamasAir window glass, and I’ve had to tweak it a bit. It shows the relevant area…all the blurry dark stuff is part the pine forest of the National Park 

Image - Version 2

ADDENDUM 2 In response to a comment about the power of hurricanes, here is an image I have posted previously of a large rock some way out from the Delphi beach. Before Hurricane Irene in 2011, it was a solid rectangular slab. This is what it was like after Irene had moved on northwards  Delphi Blasted Rock