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Dunn's Hole Cave

Mar 31, 2006, 10:30 - 22:30 EST

 

District: Stewart Town

Parish: St Ann

WGS84 L/L: 18 21 43.4; 77 26 50.8

 

JAD69: 202599 E, 189842 N

JAD2001: 702710 E, 690130 N

Altitude: 170m (Dunn's Hole Cave)

Accuracy: +/- 10m horizontal; +/- 15m vertical

Type: Chamber cave

Accessibility: Vertigear

Depth: 70m

Length: 200m

Explorers: NSS - 1957

Survey: BRG McGrath - 1958, JCO - Mar 31, 2006

JU Ref: Text - pg 164; Map - 164

 

Entrance size: 25m W x 52m H

Entrance aspect: 170 True

Vegetation in general locale: Bush/farm

Vegetation at entrance: Bush

Rock type: White limestone

Bedding: Poor/massive

Jointing: Poor

Speleothems: Few. Stals.

Palaeo resources: None

Archaeo resources: None

Hydrology: Wet

Siltation: Great

Sink: Active (Spring)

Rising: N/A

Stream passage with surface activity: Flowing

Stream passage without surface activity: N/A

Dark zone: 0%.

Climate: Warm, humid.

Bats: <1000

Bat guano: Some

Guano mining: None

Guano condition: No accumulation (individual faeces)

Eleutherodactylus cundalli: Some

Neoditomyia farri: None

Amblypygids: None

Periplaneta americana: None

Cave crickets: Undetermined

Sesarma: None

Other species: This cave is entirely in the twilight zone. No trogs are present. The bat roost is believed to be limited to Artibeus jamaicensis. Stygobites were not seen, and would not be expected due to the great input of silt to the cave (downstream fissures/passages are mud-choked). American roaches are not present, presumbably because no one enters this cave, and it is rural enough that there is no rafted garbage.

Visitation: Three visits in the last 50 years.

Speleothem damage: None

Graffiti: None

Garbage: None

Ownership: Private

Protection: None

 

Vulnerability: Medium. The flora of the hole itself, rather than the cave found at the bottom, is unique. Because of the difficult access, invasive species have been limited to what is transported via natural means. We observed a fern species, looking somewhat like a low tree-fern, growing in the hole itself that I cannot remember seeing before (N.B. my knowledge of Jamaican ferns is limited). A species of liverwort was thick on the walls of the hole (not the cave), that appeared to be a common species, but the profusion of it was notable. We did not spend any great amount of time looking at this, but casual observation showed the flora at the bottom of this very deep hole to be markedly different than that found at the top. The illumination of the hole itself is very particular; the depth, and narrowness, is such that parts of it receive direct light for at most several hours a day, and this restricted to the two periods when the sun passes directly overhead, this totalling perhaps two to three months out of the year. This site, biologically, is important in the outer sections moreso than in the cave, because of it's great inaccessability, and lack of human disturbance.

 

Dunn's Hole and Dunn's Hole Cave
March 31, 2006
Team: G Van Rentergem, H De Splenter, RS Stewart, IC Conolley, E Slack, J Vacianna.
Notes: RS Stewart

The entrance to Dunn's Hole Cave - Photo by Guy van Rentergem

Dunn's Hole was not part of the original plan for the March 2006 expedition, and was only decided on three days before our visit. What led us there, albeit indirectly, was Smokey Hole Cave.

On Sunday, Mar 26, five days before our visit to Dunn's Hole, we successfully explored and surveyed Smokey Hole Cave, but a quick field estimate of the depth at the time had led us to believe that it was only 157m to the bottom of the shaft, and therefore not a new record as we had hoped it would be. On Monday evening, after taking the day off due to lack of sleep the night before, we returned relatively early to the Last Resort, in Windsor. Hilde and Elizabeth cooked some excellent food, and everyone was planning on an early sleep. After the others had gone to bed, while finishing my last beer and having a contemplative puff, I hauled out my copy of Jamaica Underground and pondered the list of the deepest known caves in Jamaica. At the top of that list is Dunn's Hole. Our depth at Smokey, assumed to be 157m, put it in fourth place. I had been of the thought for a long time that the JCO should be familiar with the deepest cave on the island, and accordingly, it was on my to-do list, but because the entire extent of the cave was known (nothing more to explore), I had seen no rush and had pencilled it in for 2007, this being the fiftieth anniversary of the first descent (NSS - 1957). However, my eyes kept returning to that list in Jamaica Underground, and Dunn's kept sitting there, right at the top. It was no great distance away (Stewart Town) and involved only an hour's drive. It seemed unlikely to me that the others would also suddenly want to see it in real life, as I now very much did, especially after all the planning that had been involved for Smokey, but as I made my way to bed, I decided to ask Guy what he thought of the idea in the morning.

On Tuesday morning, as I finished a very strong cup of coffee and my brain resumed functioning, I remembered Dunn's. In the bright light of day, it seemed a rather silly idea, tackling a cave said to be 230m deep, which we knew the NSS to have found difficult, without us having given any thought beforehand to logistics, but I decided to suggest it to Guy anyway. Surprisingly, he thought it was a fine idea, and his only concern was the drive required. Upon learning that it was only an hour away, he became enthusiastic, and within minutes we had decided to knock off Dunn's on the coming Friday. When Hilde and Elizabeth next wandered by on the porch, we passed the news along. Elizabeth was slated to leave us on Wednesday, gone for the rest of the expedition, but after her asking of me if she would be part of the descent team, and my telling her, "Yeah, man, you're coming down", she decided to see if she could alter her plans. Later in the day, when I was getting a signal with my cell-phone, I called Ivor in Kingston to let him know what was afoot. Judging by his laughter, it seemed that he thought we might have lost our minds, but he was definitely interested in being part of it and would see what he could arrange (transport would again be a factor for him, having to come from town). On Wednesday, Elizabeth returned to St Mary, but made it clear that if there were any way she could return on Friday, she'd be back. On Thursday, March 30, we received word from both Ivor and Eliz that transport had been taken care of, schedules changed, and that they'd be with us. When we arrived at Dunn's, on Friday, we had a very solid, highly experienced, compact team in place, and what I had considered to be a potentially irresponsible plan on Tuesday morning would prove, in the end, to be a piece of cake, entirely because of those who were there.

Friday, March 31, was one of those rare days when we all ran early. The plan was to meet at 10:00 AM at the Stewart Town square, and then make the short drive south to the Endeavour district where the cave is located. Guy, Hilde, and I were out of Windsor not long after 8:00 AM, and arrived in Stewart Town well before 10:00. Ivor and Elizabeth had the good fortune of getting a drive from Kingston with a very nice lady from UWI, Joan Vacianna, who would take on rope-watching duty at the top of the hole, and despite the distance, they were at Stewart Town not long after us. Now assembled, next came the drive down the road to the south. This road had been impassable for a long while after Hurricane Ivan (during our visits to the nearby Drip and Belmont caves), but because both of the vehicles we were using were 4x4's, and the road had seen some attention in the last months, we soon arrived at the t-junction of Endeavour, and were, in theory, somewhere close to the hole.

The first order of business was to actually find the hole. None of us had looked for it before, but I assumed that because of its great size it would be well-known in the district (as it turned out, we didn't meet anyone during our visit to the cave). We also had the JAD69 coordinates from Jamaica Underground, which plotted it just west of the road, just south of the t-junction, and also an elevation map of the cave that showed the road running along a cut into the hill immediately above it. We began our search by simply driving slowly along the road south of the junction, while looking out the windows to the west. Within a hundred metres, we could see the signs of a very deep cockpit right where the JU plot said it should be. By the time we had found a place to turn around, we had had a good look at the road side of the pit, and had spotted an old track to the south. Now, knowing that we had found it, we returned to the junction to park the cars in a spot where there was plenty of room for passing drivers.

During our intitial investigation, we'd spotted two possible routes to the hole: on the south side, there was a vague track running toward the side of the pit; to the north, there was a large field, adjoining the road, that gave easy access to what looked like a very short section of bush leading up to the edge of the hole. We started out by making the easy trek along the edge of the field (a fine crop of well-tended sweet potatoes that we were careful to not step on) to see what could be seen. I should note that this was my suggestion, and although it would prove to be helpful, eventually, all of the ropes/gear wound-up coming along, which was unfortunate (especially for Ivor who was carrying the Monster Rope), because this side would turn out to not be the best way down.

On this day, I was on machete duty, so I went out front. During the previous expedition, I had picked up a new 26 inch machete, being tired of always borrowing other people's old, dull cutlasses, and had hired Pem-pem to give it a first, expert sharpening. The file that I'd bought for that had been lost, but at the start of this session, I'd picked up a new one, and was touching-up the blade every morning (and some afternoons). As a result, during the entire expedition, I had a razor-sharp, excellent cutlass, and very much enjoyed using it. So, this day, in my enthusiasm to carve a track through the short stretch of bush that lay between the field and the hole (to finally have a look at it), I ended up out of sight of the others. When they caught up, I received a minor scolding from Eliz for having done this. She was right, of course; it's JCO policy that we keep good communication/location happening at all times, in case one of us has an accident. But, in my defense, I can say that I assumed they'd see the path that I chopped (I chopped extra just to make sure they could), and it was a very short distance to shout across. In my humble opinion, it all goes back to the very first session that she was onboard for, when I gave her a minor scolding after Elizabeth's Cave - since then, she takes advantage of every opportunity to turn the tables on me. Who knows... maybe it will keep me from mishap someday, and it's a good reminder that the few rules we have apply to everyone, including the Chair of the JCO. At any rate, we were all soon assembled at the edge of what was undoubtably Dunn's Hole, with a vertical wall of well over a hundred metres below us extending into the deepest cockpit I've ever seen. It was very, very criss.

After we'd found an overhanging spot that supplied the best view, the traditional tossing of rocks took place, and this was very instructive (and also very impressive as the rocks smashed and echoed at the bottom). If we were to hang ropes where we stood, they would pass through the tops of a few trees that clung to the cliff-face, and then down a massive vertical with no ledges en route. To the right, away from the road side of the cave, the ground steepened upward, and even though the vertical below seemed more stepped, it would be very difficult to reach an anchor point and we would have to deal with even more trees below us. Across from us, toward the alternate route (the track we had seen to the south), it looked much more do-able, with the descent through a steep ravine. With some knowledge now of the layout of this monster, it was decided that Guy would hike around, via the road, to check the track, while we stayed in place to identify where he was in relation to the layout we could see in front of us. We had the radios with us for discussion, and a shout would make it across the pit to determine direction.

Guy headed out, and was to the trail within fifteen minutes and giving us short, loud shouts so we could place him. We could see that the ground below him was sloping, rather than vertical, and by radio he told us that the track seemed to lead very close to the hole. This sounded much more promising than where we were, so the decision was soon made to tackle it from that side. Accordingly, we gathered up the ropes and gear (Ivor again bearing the Monster Rope), and hiked back around to the road, and then to Guy's track.

Ivor and the Monster Rope - Photo by Guy van Rentergem The track that leads into the bush was quite easy to follow for the first fifty metres. It appears to have been well-used in the past (probably for lumber), and contours along the side of a hill that falls away steeply to the right, running under a sparse canopy of secondary growth. Ahead of us, to the southwest, the terrain could be seen to run down into a saddle that lay between us and the hills on the west side of the hole. We carried on, aiming for this saddle, with the hill still descending steeply to the right, and the forest now opening up somewhat. A session of chopping through a large patch of the common invasive fern followed, and then as we came again under the cover of a few trees, we decided that there was little more to be gained by getting further into the saddle. Where we stood, the hill fell smoothly to the right toward the hole, under fairly open forest, and it seemed as good a place as any to establish our first anchor. We dumped our loads, located a suitable tree, and tied the first of our ropes to it.

The descent that would begin our entry into Dunn's Hole was down a steep, forested hillside, and although much of it could be scrambled by hanging onto trees, the slope was great enough that a rope would not only make things safer, but faster. This first rope would be the 100m 10mm line. To get it running straight down through the trees, the chosen method was to have Guy go first on rappel while feeding the tail end out of a rope-bag. At the top, for the time-being, we would retain the 100m Monster Rope, and the 60m 11mm line. The Monster Rope would be used next, being judged a good choice for the rockier terrain we expected to encounter lower down, and once we had the first of the team at the bottom of that, we would know if we would have to bring the 11mm line down to finish it off. We had no concerns about finding suitable anchors, because the NSS information for Dunn's indicated a series of steps that offered many staging spots to tie ropes and assemble crew en route, making this pit quite unlike the sheer vertical at Smokey. Our plan of attack seemed sound, and accordingly Guy led the way, rappeling down through the trees, feeding rope from a pack as he went.

Guy was soon out of sight, hidden in the bush below, but about ten minutes later he radioed up that he was at a step in a ravine, and had run out the full length of the 10mm line. Now would come the Monster Rope. Our chosen method for getting this giant down to where Guy waited was to have one end clipped to my harness, and have the rest fed out from a coil at the top as I rappeled down. When I reached the step, it would be stretched out straight up the slope through the trees, and we could simply pull it down to where we were. This technique worked perfectly, and I was soon with Guy at the step and we were hauling down the line. Next, the Monster Rope was tied to a convenient tree, and the free end was lowered down the vertical below, this being close to 90 degrees. Here, at this second anchor, even though we were still some distance above the bottom of the pit, the view was incredible. Steep hills rose to the left, and across from us, a giant sheer wall towered over the still unseen depths. Large primitive-looking ferns, of some uncommon species, tree-like in the lower parts, grew on the more level parts of the ravine. This great, stepped gully that we descended through is notable in itself - it apparently begins at the saddle above (just beyond our top anchor), and then cuts its way, ever more steeply, down the sides of the cockpit, until in the lower sections it consists of a series of vertical pitches of ten to twenty-five metres, all separated by shelves that cross the ravine. At the very bottom, just before the cave entrance, a spring rises from the rocks to run into it, and this water flows through a last series of steps over giant breakdown boulders to enter the cave (the route we took is down the left side of the profile on the map found at the bottom of this page). However, I am getting ahead of myself - Guy and I are now at our second anchor point, with the next rope in place.

Guy again got on rappel, on the Monster Rope, and headed down. After a short time, he radioed up that we would indeed have to use the 11mm line, since there was still one last set of verticals between him and the cave. Ivor, still at the very top, copied this and let us know that he would bring it with him. I was next on the Monster Rope, and after descending several, terraced verticals, and scrambling down 50m of rocky slope, was with Guy just outside an incredibly large cave entrance. Before us, immediately under the massive wall on the north, an opening at least 30m high led into the cliff. Just below us, great boulders stretched across the floor of the entrance, their inward faces presenting the final verticals for which we'd use the 11mm line. Turning to look around, we could see the steep sides of the hole rising upwards until only a small piece of sky was left between. In truth, the entrance to this cave, massive and set in an incredibly deep pit, is probably the most spectacular on the island.

Hilde at the bottom of the Monster Rope - Photo by Guy van Rentergem Hilde had gotten on the top rope as I had started my descent on the second rope, so she quickly caught up with us and was soon coming down the last vertical above us. Next would come Ivor and Elizabeth, and the rigging of the final rope, the 60m 11mm line, required to get us down the giant boulders at the entrance to the cave. I should mention a problem we had with communcations at this point. We had three radios, two of which were high-power. One high-power unit would remain at the top with Joan. Of the two remaining radios, I had one and Guy had the other. Without thinking, I had brought the radio I was using all the way to the bottom, rather than leaving it at the change-over from 10mm to Monster Rope, and as a result, we had no communications from there to the bottom. The distance was such that little could be done by yelling, and the best we managed was "On-rope!" and "Off-rope!". This turned out to be good enough, but we were sure to alter things on the way up, when we had the first ascender take the low-power radio, and leave it at the change-over, with us keeping it there until the second-last of the team reached it. This would also have been a much better system for Smokey than what we used, and we have to remember it for the future.

The final rope, the 11mm, was soon tied to a tree and thrown into the cave. I have no recollection of what order we descended in, but the vertical was short enough that we were all quickly down. Now, we scrambled down a steep slope of smaller boulders, stones, and dirt, into the largest chamber I've seen in my life. Guy's survey afterwards showed it to be 200m long, 100m wide, and 80m high, but just reading those numbers doesn't give a true idea of what it's like when you're in there. Imagine a giant ellipsoidal structure, two football fields long, and one wide, with a ceiling 27 stories high, and then fill the area outside of this with solid rock. Make this rock smooth enough that it bounces sound quite nicely, and have the curved walls focus the echoes. Through the middle of this, run a flowing stream, in a channel carved ten metres deep into fine-grained semi-compact mud. In the air, put a light fog that makes the far walls hard to see, despite the light that arrives through the seventeen-story high entrance (which, of course, is at the bottom of a 200 metre pit, and not well-lit in the first place). Now, put yourself about half-way into this, near the west wall, sinking into mud deeper than your knees, knowing that it's a very long way down to solid rock, because this is where I soon was.

I believe that all five of us were equally impressed when we finally entered Dunn's Hole Cave, since some time was collectively spent just standing around where the rope had dropped us, alternating between saying things like, "Look at the size of the bloody thing!", and silently staring. Eventually, the caver in each of us kicked-in, and we all wandered off across the great expanse to see what could be seen. I decided to head to the wall to the left, and follow it around. This went fine for the first while. I reached it, no problem, despite sinking into mud a little, and turning to the right, I made my way deeper into the cave. The floor of the cave did not improve as I did this, and after about 50 metres, the mud floor was becoming ever softer, to the point where it was hard to pull my feet out. I carried on (not particularly wanting to turn back to return to the entrance area, where I could cross the stream-gully to get to the other wall of the cave), looking for patches that seemed dryer. This was not to be. At my far point, on that side, I was slowly sinking up to my knees in soft, damp, fine-grained silt/clay. Several final steps were accomplished, with great effort, and then I could no longer extract my feet. As I wobbled, feet stuck to the floor, and gradually sinking deeper, I briefly thought of the depth of the mud below me, and had visions of slowly sinking away to finally leave only my helmet sitting on the surface (having undone the chin-strap en route). From what I recalled, reading about quick-sand, etc, the best idea was to float on it, horizontally, so my worst-case scenario plan was to lie on it, and swim across the top, as it were. However, I had no desire to get that dirty, and wasn't particularly worried yet, so I instead tried doing it with hands and feet, keeping my knees off of it and moving like a quadrupedal spider. This worked quite well, after the intitial exertion of getting my feet unstuck, and I was soon out of the worst of it, on my feet again, and working my way back to the entrance, to then link with the others along the other wall.

A detour to the left, toward the center of the cave, as I made my way back, showed the stream-gully to be impossible to cross - it was deep, wide, and carved into the same material that had just caused me to get stuck. I swung back away from it, and skirted well to the side until I was at the solid rock of the entrance area. As all of this had been taking place, the sights and sounds were fantastic. From my spot in the mud near the west wall, the others, on the far side of the chamber, looked tiny, with their headlamps illuminating very small sections of cave around them. Voices could be heard, but the long sustain of the echoes blurred them into extended tones, with no vowels or consonants apparent. The few times I tried to shout across to the others, it was laughable - my voice came back to me in an unintelligible roll of sound that seemed to take forever to finally fade away. There wasn't just one echoing bounce, of course - it repeatedly criss-crossed the chamber from one side to the other, until you were surrounded by it [1]. So, accompanied by this surreal sound-track, I slowly caught up with my fellow lilliputians, on the east side of Dunn's Hole Cave.

The east side of Dunn's - Photo by Guy van Rentergem The section from the entrance area to the chamber east of the stream-gully starts out higher and dryer than the west, although still floored with mud. However, the mud here is dry, and deeply cracked. Some of the fissures in this surface were 15cm across, and over 60cm deep, all joining to form irregular polygons and curving triangles, spread across a large expanse of the floor. We did not feel good about walking on it, since it looked so pristine, but did so anyway, trying to step lightly. It was our belief (and hope), as we did this, that the floor receives regular resurfacing, at least during times of severe weather, and since it would probably be decades until the next vist occurred, as it had been since the last, the damage would eventually be repaired. At any rate, the amount of disturbance we caused in total by crossing this was not great, and we tried to use the same route on the way out.

On the edge of this cracked terrain, there is one large stalagmite. Other than some flowstone, I don't recall seeing much else in the way of formations anywhere in the cave, so as though to make up for it, the one stal is appropriately gigantic. The width is about four metres, it is over ten metres high, and it is made up of tiers of beautiful flowstone. Despite it being the height of the dry season, there was a great amount of dripping of water down the sides, with this causing it to look like a large, calcified, champagne fountain. The colours consisted of golds and rich browns, and the moisture made it glisten and shine. It put me in mind of the legends associated with many caves in Jamaica that talk about "golden dishes set on golden tables", and I would suggest that these now be expanded upon to include "golden champagne fountains" (although stacks of glasses filled with cold, sparkling Red Stripe would be preferrable).

Upon reaching the great stalagmite, I had basically caught up with the others, although they were scattered about somewhat. Guy and Hilde were diligently surveying, Ivor was off looking into the stream-gully, and Elizabeth was lingering at the stal. After a few minutes, I pushed on further along the east side of the chamber to search for where the stream finally sank. Eliz was along for part of this, and after about 50 metres we came to a long, thin pool that lay along the side of the chamber. The drop into this from the muddy floor above was about six metres, and impossible to scramble - all we could do was look at it from the top. We carried on along the side of this to soon intersect the stream-gully, which had done a turn to the right (east) as it travelled through the cave, to eventually feed this pool. A bit of searching found a spot upstream where it was possible to cross a narrow, low part of the stream, by way of a large enough leap to clear the especially soft mud on the banks, and after a run and a jump, I was across.

On the other side of the stream-gully, a steep hill of dryer mud led upward. I scrambled up this, then after a bit of ups and downs on heaps beyond, I reached the high point of the central section of the cave. I can speculate that I was actually on the top of a pile of breakdown boulders that were well buried under mud, but it's hard to be sure. What was most notable about this section, though, was the presence of rafted debris, in the form of sticks, old chunks of wood, etc, at the highest points of the hill. At some point over the last couple of years, that hill, and therefore the entire floor of the cave, was underwater. It flitted through my mind that our theory on the cracks getting resurfaced, which would erase the signs of our passage, would indeed occur, and I was able to get rid of the little tinge of guilt that lingered. I sat myself down at this high-point, lit a cigarette, and tried to imagine the amount of water that it had taken to fill the chamber that lay below me. Sometime during the last two years, perhaps during Hurricane Ivan, there was a true lake in that cave, covering a couple of hectares, and 20 metres deep in places. When this filling was underway, it must have been an incredible sight, as the great hole outside of the entrance funnelled the rains and fed the water through the entrance. The last of the verticals were probably waterfalls, with the flow booming into the lake below. The sound alone must have been fantastic, and if one had had the wherewithall to get down there a day before the hurricane hit, and find a good perch high on the side of the entrance (perhaps bolted ten metres up the wall), it would have been a magnificent experience [2].

Before I move on with this account, the floor of the cave, and the resurfacing, should be addressed further. At present, a stream begins where the spring enters the cave, and cuts through deep layers of silt, centrally through the cave, until the pool is reached. During extreme weather events, i.e. hurricanes, when the cave is flooded, the course of the stream might change, as well as the surrounding terrain. The pool will no doubt always be in the same place, because this is where the water apparently exits the cave, but the dimensions of it might not be permanent. In short, the topography that we observed in the cave may be temporary, and greatly altered at times. I suspect that my smoking spot is relatively permanent, as it did suggest a mud-covered breakdown pile, but I cannot even be sure of that. It would have been very informative to have been in there before Ivan - for all we know, the pool was at one time as wide as long, with an obvious exit point through a choke low on the wall, and has now been thoroughly mud-choked due to a massive, sudden input of silt from the hills surrounding the pit outside.

By the time I finished my cigarette (and for those purists who are aghast at me having had a smoke in the first place, yes, I took the butt back out with me), Guy and Hilde had caught up, surveying their way along. I lent a hand for a few minutes, holding the target in the final section, and we then turned and began the journey back out of the cave, joining Elizabeth and Ivor en route.

Our return to the entrance was uneventful, and we were soon at a small flowing pool, held in rocks, not far from the bottom of the 11mm rope, washing the cave mud off of our boots and hands (which would quickly return from whence it came) in preparation for our ascent. The time now was about 17:30, with sunset less than an hour away, and we had quite a distance to cover, most of it vertical, before we would rejoin Joan who patiently awaited us at the top of the uppermost rope. It didn't seem wise to have her all alone in the dark up there, sitting in the bush. Accordingly, Elizabeth was very soon on rope, and heading up.

Our plan for extracting ourselves, and the ropes, from the hole, while also allowing Guy to finish the survey up the series of pitches ahead of us, was such: First, Elizabeth would make a quick, direct ascent, stopping only to leave a radio at the changeover from the Monster Rope to the 10mm. Next would be Hilde, who would also carry on straight to the top. Third would be me, but I would wait at the change-over until the Monster Rope below was free (i.e. both Guy and Ivor at the change-over), because I would haul the Monster Rope back up the final pitch, using the same system as when it came down. Fourth would be Guy, who would survey en route, assisted by Ivor who would be below him and the last person up. This all went well [3]: Elizabeth reached Joan during late twilight, and Hilde soon afterward. I awaited Guy and Ivor at the change-over, and then after we'd hauled the Monster Rope to that point, I clipped in one end, got on the 10mm line, and dragged it up through the bush behind me as it was fed out from the change-over (this was tough work towards the top, but no problem), and then Eliz and Hilde pulled it up while I coiled it at the top. Finally, Guy and Ivor came up the 10mm line, which was soon hauled up and coiled, and we were almost done with Dunn's. One last bit of work was necessary - Guy extended the survey out along the track to the road, with Hilde holding the target and myself clearing obstructing branches with the machete. At the road, they continued the survey, and in fact didn't end it until we were back at the cars where we tied it into a good GPS position that I got while awaiting them.

We were all assembled at the cars at 22:30, and after sorting and stowing gear, we climbed in and headed for Stewart Town. From here, Guy, Hilde and I would return to Windsor, and Joan, Ivor, and Elizabeth would head for Kingston. Upon reaching the Stewart Town square, with my vehicle well in the lead, we ran into a police check point and were immediately flagged down. I climbed out, introduced myself, mentioned that we'd worked for the St Ann Constabulary at Hutchinson's, told them we'd just come out of Dunn's Hole (they seemed impressed), and although they asked a couple of cursory questions, everything was fine. Several minutes later, the others caught up, and after a little time was spent washing at the standpipe near the square, we moved on again, to go our separate ways (with the police smiling and waving as we left).

Before closing this account, I will add some brief notes on the biology of the cave, and address our decision to change the officially listed depth of the cave.

The one large chamber that makes-up the cave is being used as a roost by bats, but because it is all in the twilight zone, the roost is limited to small numbers of Artibeus jamaicensis, with the total count being under a thousand, and probably much less. The ceiling of the chamber is very wet, with much dripping in places, and this seems to further restrict the numbers. There are no troglobites present, because there is no part of the cave that is entirely dark during the daylight hours. Birds, believed to be Swallows, are using the entrance area, and Guy has supplied a sound-clip of these in .avi that can be found here (right-click and save as).

We have decided, based on the survey carried out this day (found below these notes), that the old figure of 230 metres for the depth of Dunn's Hole needs to be altered. The cave itself is only 70m deep, while the hole in which the entrance lies is 190m. We have split Dunn's into two sections, Dunn's Hole and Dunn's Hole Cave, and accordingly moved the cave well down the list of the deepest known caves in Jamaica, with Smokey Hole now at number one at 194m.


[1] The smoothness of the walls and the shape of this great chamber combine to make the acoustics very particular, and very entertaining. The chamber is essentially the upper half of a slightly-inclined horizontal ellipsoid, with an opening at one end. At the west wall, the distance directly across to the east wall is about 100m. This gives a return travel time of 2/3 of a second for the first echo. However, the curved walls to left and right, across from you, are also bouncing the sound back, as is the ceiling. This runs out the first set of echoes to about 1 second. It doesn't stop there, of course, because the surfaces are smooth relective rock, free of sound-dampening vegetation etc, and the repeated, contained bounces cause the last fading sounds to arrive five to ten seconds after they first left you, depending on where you are in the cave. One can speculate that the shape of the chamber supplies a couple of particularly good spots, these perhaps at the two foci of the ellipsoid, quite close to each other in the center of the cave. It would be interesting to wander around in this chamber timing echoes until the sweet points are found, although I believe these might be in the stream-gully area, so you could need pontoons to do it.

[2] Guy and I have discussed, several times, attempting to get into certain caves just before a hurricane hits. One would have to be circumspect about the choice of cave, and be prepared to stay for several days, but this is well within the realm of our expertise. The only thing stopping us from doing it is not having the money that would allow us to suddenly jet off, on a very last minute basis, to Jamaica. I am hopeful that some day I will get lucky and be on the island when a hurricane is about to hit, and if this happens, I have several targets in mind. Logistically, the main concerns are having enough water, food, batteries, cigarettes, and alcohol to last for a few days. A good book might come in handy, to kill time until you can get back out. This plan is definitely on the to-do list, and it's only a matter of timing.

[3] "Well" in this sense means that we were successful. However, at one point when Guy was on the Monster Rope, with Ivor below him, an old log that was perched in the ravine let go and tumbled into the hole with a terrific amount of crashing as it went down. Fortunately, Ivor dodged this as it came toward him, and was fine. It took a minute for us to find this out, because he had dropped the radio when he scrambled out of the way. When he had refound it, and replied to my repeated questions regarding his condition, he told me, "yeah, I'm alright, but I lost the radio". Hearing this, I was of course relieved, but I had a momentary sinking feeling, dismayed that we'd lost one of the new, spiffy radios, then suddenly realized that he couldn't have lost it permanently, because he was using it to talk with me.

Map of Dunn's Hole

Area Map for Dunn's Hole

Detailed Area Map for Dunn's Hole

Jamaican Cave Notes - Main Page