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Hulls Cave

March 26, 2009

Videos: Jan Pauel on the importance of bats (11 MB wmv)
Overview of the visit by Guy Van Rentergem: Low resolution (27 MB wmv), Medium resolution (51 MB wmv)

District: Aboukir

Parish: St Ann

WGS84 L/L: [Reserved - by request only]

JAD2001: [Reserved]

JAD69: [Reserved]

Altitude: 610m WGS84

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


Type: Shaft to cave

Accessibility: Vertigear

Depth: 105 m

Length: ~45 m

Explorers: JCO - 2009

Survey: JCO sketch map - 2009

JU Ref: N/A

JU Map: N/A

Entrance size: ~5 x 8 m W

Entrance aspect: 185 deg true

Vegetation in general locale: Scrub/bush/farm

Vegetation at entrance: Bush

Geology: White limestone

Bedding: Poor/massive

Jointing: Poor

Speleothems: Stals

Palaeo resources: None seen

Archaeo resources: None

Hydrology: Dry

Dark zone: 0%.

Climate: 20 deg C, semi-humid.

Bats: >500

Bat guano: Much

Guano mining: None

Guano condition: Fresh/fluff

Visitation: None

Speleothem damage: None

Graffiti: None

Trash: Some (a few items tossed in shaft)

Ownership: Private

Protection: None

Vulnerability: Medium. Deep guano deposits - would be high vulnerability if access was not so difficult.

Click for large size
On the breakdown boulders looking up toward the entrance. Photo: Kurt Garrez.
Click for full resolution.
Hulls Cave
March 26, 2009
Team: RS Stewart, K Garrez, J Pauel, G Van Rentergem, A Ekparian, D Ingleman.
Notes: RS Stewart

On January 31, 2004, the day before the first Jamaican Caves Organisation (JCO) visit to Hutchinsons Hole, our team explored a deep shaft near Aboukir that had been brought to our attention in an email a month before. The name assigned was "Berties Sinkhole", after the owner of the land where it's located. During the visit, we had not met Bertie himself, just several members of his family. Subsequent plotting of the GPS position showed it to be unlisted, and, in fact, the first speleo site noted for the entire district. In our experience, finding one deep shaft in a district usually indicates there are others nearby, often located along a fault-based lineament. A return to the area was put on the to-do list. As it turned out, five years would pass before this finally happened.

In late 2008, an email arrived informing of us of deep caves near Aboukir. We pencilled it in for the March 2009 expedition - the district is located conveniently close to Aenon Town, where we'd already planned to be based for several days.

On the morning of March 24, 2009, having arrived in Aenon Town the night before, the team hit our usual breakfast spot in the nearby town of Cave Valley. During the course of things, a route-taxi driver, "Dave" aka "Homy", who remembered us from our Cave River System visits, informed us of several caves in his home-district of Aboukir, on land owned by friends/family, which he very much wanted us to explore. This coincided perfectly with our plans, so phone numbers were exchanged, and arrangements made to visit the area on March 26.

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Looking down the entrance shaft. Photo: Kurt Garrez.
Click for full resolution.
On the morning of March 26, we met with Homy, told him our plans were still on, and he made the necessary phone calls. Soon after, in a convoy of two vehicles, we headed for Aboukir. I was pleased and surprised, upon our arrival, to meet Bertie himself. Better yet, he remembered our previous visit, having apparently heard a thorough account afterwards, and he expressed a great willingness to show us several more caves he knew of, roughly a km down the road. These included a deep, unexplored hole, which we decided would be the first target. The Landrover was already overflowing, with six of our crew inside, leaving nothing free but the roof, but obligingly, Bertie ascended the rear ladder, and off we went. Navigation was supplied by shouts from above, and within five minutes, a final call told us to pull over. A suitably wide part of the road was found for parking, equipment quickly extracted from the vehicle, and vertigear donned. We deemed two ropes enough for the exploration: the 100m, 13mm Monster Rope, and a shorter 9mm line in the unexpected event that the hole would be especially deep. Guy, as at The Asuno, hoisted the main rope on his back (strapped to a large pack-frame - a method that works quite well), once again taking more than his fair share of the load. The 9mm line, which weighs nothing, was picked up by one or another of us, and the long etrier was stuffed in a pack. Thus prepared, our intrepid crew, accompanied by a sizeable audience of local people, set out to see what awaited.

A description of the approach, and location map, have been removed from this online report, and are available by request only.

Once at the hole, the traditional tossing in of rocks was carried out. As usual, we could not see down the shaft from the easily accessible section at the top, but they were obviously bouncing off the wall of the pit as they fell, giving no solid guidance on the depth, other than it was over 30m. No matter - we'd know once we were hanging from a rope in it. Accordingly, a stout tree was found well upslope, the 13mm rope was tied on, tossed in the hole, and I got on rappel (I volunteered, having been second at Morgans earlier in the week).

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Looking directly up the shaft. Photo: Kurt Garrez.
Click for full resolution.
A slope at about 30 degrees extended about 6 metres to a short pitch of 2-3 m. Beyond that, another slope of about 5 m led to the actual edge of the shaft. I worked my way past the lip, got my feet on the wall, and had a good look down. It seemed to be a fairly short pit, perhaps a little more than 30 m, but not much. I headed down, moving slowly with four bars of the rack on the 13mm, actually having to feed rope through. Some 20 m passed, as I concentrated on picking up speed by spreading bars and lifting the tail of the rope, before I kicked up the headlamp to the 3 watt beam, and looked for the bottom of the rope. I couldn't see any coils on the floor, but knowing there was roughly 80 m of rope in the pit, assumed it just wasn't visible yet. I kept going down, free-hanging away from the wall as the shaft widened, and a surprising amount of time passed. Finally, I saw the end of the rope - dangling a metre or two above the floor. I stopped, tied off the rack, and radioed up that we had a bit of a problem - the rope didn't reach. I felt like an idiot reporting this, as I'd already estimated the shaft at about 30 m. More important was what I'd do now. If the rope ended just a metre above the floor, I could get off at the bottom, then the top-side crew could find a lower anchor, send the next person down, and we were on our way. I descended a little more, took another look, and started to think it was more than a metre off the floor, in which case it would be impossible for me to get off rappel. I also noticed at the bottom an opening to the side, extending to the north, although I couldn't tell if it were a passage, a chamber, or just a widening into a choked soak-away. Wha' fi do, I radioed up that I was changing to ascent, and headed back up.

My ascent back to the anchor was about 60 m, and took about 25 minutes. Once there, we rerigged the mainline to a lower tree, using the 9mm line to get to it from the top, and then I invited Kurt to go next - I needed time to recover from the ascent. He was glad to do so, and headed down.

Hulls Cave Sketch Map - Plan
Rough sketch map of Hulls Cave - PLAN. Very approximate.
I must confess that I fully expected him to hit bottom and report a simple, blind shaft, like Berties Sinkhole, in which case, all that would be needed was a quick look, an altimeter reading, and we'd be done with it - I had no great desire to spend more time on rope in a deep, unimportant pit one day after having done The Asuno. However, once he touched down, he reported a large chamber, complete with bats, extending under the hillside above. That is, a pristine bat-roost, which is a rare thing in Jamaica. Accordingly, I got on rope, and rappelled down to join him.

The following description of the cave must be prefaced by the following:

Those who may be interested in the guano are advised that it isn't possible to mine it, despite your best efforts. The entrance pit is 300 feet deep, mostly straight down. You would die in the attempt, on some make-shift pulley system, for what is commercially a small amount of fertilizer. Don't even think about it - just leave the site alone, and respect it as one of the few pristine bat-roosts on the island. Even better, plant a few trees around the outside to improve bat foraging opportunities.

The bottom of the entrance shaft intersects a large dome-shaped chamber, about 40 metres across, and 20 high. A pile of breakdown boulders extends from the shaft to the centre of the chamber, rising a couple of metres in the mid-section. To the right as one looks inward from the shaft, a scramble past a tall, broad stalagmite leads down to the floor of the chamber. Here, deep deposits of fresh/fluff guano cover most of the floor around the perimeter of the chamber, in places rising over 80 cm above the surrounding layer. The total depth is undetermined. The ceiling above hosts at least 500 bats, with numbers perhaps in the thousands. Roosting seems to be wide-spread, although I chose to not use my 3W beam to look closely, not wanting to disturb the bats.

Hulls Cave Sketch Map - Profile
Rough sketch map of Hulls Cave - PROFILE. Very approximate.
I worked my way carefully around the outside wall of the chamber, stepping on rocks that protruded from the guano when possible, and generally sticking close to the wall in a fairly thin layer. I steered around several particularly deep deposits en route to my farpoint, about two-thirds of the way around the chamber from where I'd started, then returned using my previous track. I am confident that I caused very little damage to the deposits, and none whatsoever in the most important parts.

At the last deep deposit before I returned to the stalagmite, I stopped, extracted a hand-lens and reading glasses from my backpack, and leaned carefully over the guano to search for inverts. I hoped to find Collembola, having seen them in great numbers on similar deposits at Marta Tick, but saw none. In fact, I could not find any macroinverts whatsoever, other than a small, white moth (possibly Decadarchis or Tinea) that is common in Jamaican bat caves. A return visit should be made to collect several small samples of guano to study under the microscope.

Cave crickets (U. cavicola) are present on boulders and formations in the cave, but not numerous.

Webs of some sort of Araneae were noted in several fissures, but the species that made them was not found - it needs a closer look.

The common invasive roach P. americana was not seen in the cave. This reinforces the pattern already noted by the JCO that the roaches are restricted to caves that have been mined for guano.

Kurt began his ascent while I was searching for critters. By the time he was at the top, I had seen enough for a first visit, and in turn got on rope. My ascent was uneventful, although slow. My legs were begininning to feel the effects of the various deep pits we'd done in the previous days. Nevertheless, I reached the top with enough time left in the day for us to proceed to the next of Bertie's caves. This was within hiking distance, and turned out to be a perfect site for giving our two new Peace Corps Volunteers a little training in vertical work, on a 10 m pitch. A report will follow for what we called Berties Pit Cave.

With regard to cave biology, Hulls Cave was the most important site visited during the March 2009 expedition, and a return has been put on the to-do list, pencilled in for late July 2009. Several things need to be done, including: obtaining several core samples of the guano deposits; a thorough invertebrate bioinventory; a basic survey; and perhaps catch and release netting of the bats at the entrance to determine species make-up. This should be the only additional visit to the interior of the cave, after which it will go on the JCO off-limits list. The site will only remain pristine if we stay out of it.

We must also conduct an outreach session in the local community to make everyone aware of how important their caves are, and why they should be protected. Periodic follow-up visits will help to keep the information fresh. These will probably happen naturally in the course of exploring other unlisted sites in the area, which we suspect to exist, and to await us.

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