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… 

SAWMILL SINK, ABACO: INDUSTRIAL ARCHAEOLOGY IN A POST-APOCALYPTIC LANDSCAPE


Sawmill Sink (adventureactivist youtube)

SAWMILL SINK, ABACO: INDUSTRIAL ARCHAEOLOGY IN A POST-APOCALYPTIC LANDSCAPE

1. BLUE HOLES

The Blue Holes of Abaco are geological wonders about which much has been written – much of it in the NATIONAL GEOGRAPHIC MAGAZINE. Sawmill Sink is one of the best-known inland ones; and there are other holes in the shallow seas on both sides of the island. They are deep chasms in the limestone rock, many leading to extensive and complex cave systems under the island. Divers exploring Sawmill Sink have found many prehistoric fossils, including those of an extinct giant tortoise, and land crocodiles. Most conveniently, this fascinating blue hole is close to Delphi, hidden deep in the pine forest and accessible only by historic logging tracks.

LOGGING TRACK TO SAWMILL SINKSawmill Sink Abaco 19

AERIAL VIEW OF SAWMILL SINK DEEP IN THE PINE FORESTSawmill Sink Map copy

This article is not about Blues Holes in general, nor Sawmill Sink  specifically. I have such a post planned, but for the moment I’ll put some relevant links at the end of this one. Feel free to scroll straight there if the cumbersome heading has already put you off… but in an effort to hold your interest, here’s an image of the Sink to give you an idea of what it looks like. There are wooden steps down and a platform to enable you to swim in it (there are no crocodiles these days. So they say…).

SAWMILL SINK, ABACOSawmill Sink Abaco 8

2. A LOGGING HISTORY

South Abaco – defined loosely as the area south of Marsh Harbour – is dominated by pine forest. There are a few settlements and individual residences, all by the coast. The forested swathes are criss-crossed by an extensive system of logging tracks, many now all but impassable. They are reminders of Abaco’s historic importance as a source of wood deriving from the ubiquitous tall, slim pines. One use to which they were put was as mine pit props in the collieries of Wales.

 1996.2039.db

Last June when we went to Sawmill Sink, we saw a rusty rail sticking up from the undergrowth. We were with Ricky Johnson, the man who could invariably answer any question about Abaco; he explained that there had at one time been a light railway through the forest to carry the felled timber to the highway, where it was transported to the coast for loading onto ships.Sawmill Sink Abaco 17

Last month we returned to Sawmill Sink. The south part of the island was enduring the annual outbreak of forest fires, most (if not all) believed to be set by hunters wanting to clear to undergrowth to make hog-hunting easier. While the occasional natural fire is actually good for the forest (cf burning moorland), the set fires do great damage over a vast area. On some days there were 6 or more separate seats of fire appearing in one day – highly unlikely to be the work of nature. Thick palls of smoke drifted across the island, and out to sea. Even far out on the Marls, the fires were visible, with the smell of burning carried on the wind. This year, the fires came uncomfortably close to some of the settlements. Night-long community action was needed in some places to protect property. At Delphi, the fires came within 300 feet or so before finally fizzling out in the coppice… Two years ago, they  came nearly as close. For a post-fire wander round the Delphi drive circuit click FOREST FIRES (it was one of the first, tentative posts on this blog – and boy, does it show… it needs a rethink)

DELPHI GUEST DRIVE: A WARM WELCOMEForest Fire, Delphi, Abaco

The photos that follow show the track to Sawmill Sink immediately after a fire had swept through the area. Trees were still smouldering and in places the ground was still hot to the touch. Along the way the evidence of the former usage had been laid bare. Some images show the paved path that leads from the logging track to the Sink. I have no idea if these are the first images of so many visible remains of the logging trade, revealed by the burnt-off undergrowth. I haven’t tracked down any others at all so far. I write as a non-resident of the island, so if anyone can add any information, please do so via the COMMENT box. Sawmill Sink Abaco 1 Sawmill Sink Abaco 2 Sawmill Sink Abaco 3 Sawmill Sink Abaco 5 Sawmill Sink Abaco 6 Sawmill Sink Abaco 7 Sawmill Sink Abaco 9 Sawmill Sink Abaco 10 Sawmill Sink Abaco 11 Sawmill Sink Abaco 12 Sawmill Sink Abaco 13 Sawmill Sink Abaco 14

Finally, we found this rock close to the Sink. Are those plant fossils? Bearing in mind that sea probably covered this area entirely (the highest point on Abaco is a mere 134 feet ASL), might these be anemones or sponge fossils of some sort? Comments from fossilologists welcome.

STOP PRESS thanks to FOSSIL LADY (aka Kathi) for the following: “Those don’t look like plant fossils to me, they remind me of stromatolites, a sponge like creature that first dominated the earth billions of years ago. Some varieties still survive today. It would be worth it to have a geologist have a look see. ps the sinkhole is awesome!”Sawmill Sink Abaco 15

SOME BLUE HOLE LINKS TO EXPLORE 

BAHAMAS CAVES RESEARCH FOUNDATION

FRIENDS OF THE ENVIRONMENT, ABACO

NATIONAL GEOGRAPHIC

ADVANCED DIVER MAGAZINE ARTICLE

As a reward for having waded through the smoke and ash above, here’s a short video of what you can see if you dive in a blue hole. It’s worth saying (1) that you need to check you are allowed dive – some holes are subject to ongoing research and (2) blue hole diving and caving is an inherently unsafe activity unless you have the right equipment and know exactly (by which I don’t mean “hey, I can wing it”) what you are doing… 

Photo credits: all RH except header (adventureactivist, youTube); pit props (Scottish Mining Museum); aerial view (Gmaps)

BLACK-FACED GRASSQUITS ON ABACO – PRETTY FAMILIAR BIRDS


BLACK-FACED GRASSQUITS ON ABACO – PRETTY FAMILIAR BIRDS

Both pretty and familiar, in fact. Birds of the pine-woods, coppice, garden… and feeder. They are an unremarkable species, they don’t have off-beat avian habits, they aren’t scarce… but if they weren’t there, you’d probably miss them. Males and females have notably different colouring, with the female having a bright eye-ring. They tend to hang out in pairs or small groups. These little birds are abundant in the north Bahamas, but like many species found there, they are only very rarely found in south Florida.

MALE BFG IN THE COPPICE NEAR THE DELPHI CLUB

A MALE BFG DEEP IN THE PINE FOREST NEAR THE SAWMILL SINK BLUE HOLE

No two books describe their call in the same way. I’m not venturing into the vexed field of avian phonetics of the ‘chip chip chip kerrrrr–ching’ variety… so here’s a very clear recording of the song of Tiaris bicolor from the excellent Xeno-Canto (Paul Driver)

FEMALE BFGs EAGERLY SNACKING ON THE FEEDERS AT THE DELPHI CLUBTHESE TWO PHOTOS SHOW THE DISTINCTIVE EYE RING OF THE FEMALE BFG