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Jackson's Bay Caves

July 25, 2010 (First of three reports for JBC. July 27-28 is here. Aug 8-9 is here.)

District: Portland Ridge

Parish: Clarendon

WGS84 L/L: By request only

JAD2001: By request only

JAD69: By request only

Altitude: 30m WGS84 (JBC-1)

Accuracy: +/- 5m horizontal; +/- 10m vertical


Type: Complex

Accessibility: Scramble or walk-in

Depth: JU has 60m but alt of JBC-1 is 30m (?)

Length: >3000m

Explorers: JCC, 1964-77

Survey: JCC

Vegetation in general locale: Scrub

Vegetation at entrance: Scrub

Geology: White limestone

Bedding: Poor

Jointing: Poor

Speleothems: Stals, flowstone

Palaeo resources: Yes

Archaeo resources: Yes

Hydrology: Wet

Dark zone: >99%.

Climate: ~23 deg C, humid.

Bats: >5000(?)

Bat guano: Some

Guano mining: None

Guano condition: Varies (needs work)

Visitation: Occasional

Speleothem damage: None

Graffiti: Some

Trash: None

Ownership: Private (Gun Club)

Protection: None

Vulnerability: High.

Jackson's Bay Caves
July 25, 2010
Team: RS Stewart, A Hyde, M Ketover
Notes: RS Stewart

This was my first visit to Portland Ridge, and from what I'd heard of the area, I anticipated difficulty finding any caves at all (scrubby, thick bush, and no residents). Accordingly, I asked Adam Hyde, who knows the area well, if he could come out for the day, and get me started with a couple of entrances. With those, I would attempt to georeference the Jamaica Underground area map to find the others.

The two of us, and a friend of his visiting from Costa Rica, Mike Ketover, made it a day trip from Kingston, with me driving the Discovery. We didn't reach the Gun Club on Portland Ridge, where the caves are located, until about noon, which meant we were tackling it at the hottest time of day. Usually, it isn't much of a problem.

Introductions were taken care of first - with "Bredda", who tends to the club house along with his family - and we then hiked southeast along the coast until we reached a Gun Club track that leads inland. The track, flagged with red paint, does not lead directly to any of the caves, but does come close to Potoo Hole, which was one of Adam's discoveries. By the time we'd reached the general area where Adam knew we should turn off and start bush-whacking, I had already begun to regret bringing only 1.5 litres of water. There was little shade, we were in the southernmost part of the island, close to sea level, and the heat of the sun was intense. This would prove to be a major factor during the entire five days I would spend in the district.

Understandably, Adam was a little unsure of the exact route from the "Red Trail" to Potoo - it had been some time, and it all looks the same (macca, agave, and cactus) - but he forged ahead, swinging his cutlass, in what he remembered as the right direction. After some twenty or thirty minutes of this, incredibly, he found the entrance hidden in the scrub. I pronounced, "You're a f*cking star, Adam - great work", and we then took a good look at what he'd found.

I believe we were at the main entrance (there are three in total), which is a pit about 6 x 10m wide that is very bushed up around the perimeter. It is not suitable for a harp trap, and it would require much clearing to erect a mist net, which would be unwise due to the archaeological importance of the site (would make it too obvious, and possibly attract visitation). We did not enter the cave, but my understanding is that the pit is 20m deep, and there are good deposits of guano, and presumably bats, in the chambers beyond. We are not posting the position of the entrance because of the archaeo significance of the cave, but can supply it by request if we deem the reason for the visit to be important, and the proposed method to be respectful.

Next on the agenda was the poorly-named, "Entrance 1", of Jackson's Bay Great Cave (JBC), which is located beyond Potoo Main (the main entrance of JBC is actually the, "Water entrance", aka, "Entrance 2"). Again, Adam went ahead wielding his machete, and after a little while, and much work and searching by Adam, we were there. This one would be entered, and we would come out at a second entrance, thereby giving me three entrances to use for georeferencing.

Entrance 1 of JBC is a collapse pit into the NE side of the main NW passage series. It is about 4 x 6m wide, and can be scrambled on two sides into the cave below. It is not suitable for a harp trap, but a mist net will work after a little clearing. However, it may not be the best entrance to net at - there are a total of 9. This is addressed in the report for the final two days of fieldwork at JBC.

Led by Adam, the three of us now climbed down into the pit - carefully. It is of no great depth (~3m), but near-vertical with rocks at the bottom, and we had no ropes (mea culpa). It would be helpful to have a short length of 9mm line (>15m), a few 3m lengths of webbing, and fig-8 descenders for this pitch (no need for full harnesses and racks), as there are trees available to use for a doubled, pullable, rappel line.

At the bottom, the route descended further over breakdown boulders for another 20m or so until we levelled out, and then Adam swung us to the east, toward Entrance 2. We soon hit pooled water, roughly knee-deep, and then a low section where the roof approaches the water. [The easiest route passes a fine formation of flowstone, with active microgours, that is on the right wall. One must take care to not touch this - you must shift left, and put up with the water at chin-level - whether you like it or not]. The passage opened up again beyond this, and after about 150m we could see the light of another entrance ahead of us, reflecting in the waters of a wide, high chamber. We had reached the "Water Entrance", as it is called by the locals, also known as Entrance 2.

The Water Entrance of JBC, like many of the other entrances in the area, is defined by a collapse pit (most of the caves are very close to the surface). The entrance itself is on the west side of the collapse, about 12m wide, and 3m high, and lies atop a breakdown boulder slope that extends down about 15m until the pool is reached. There are glyphs on the rocks near the pool, and on the wall to the left (as one looks into the cave), and on formations straight ahead. We will give no details regarding such in this report, but they are available by request.

Our mission for the day was now almost complete (one last GPS position to take), but before we exited the cave, Adam showed us the start of the crawl passage that leads to the very large eastern section of the cave, which I would visit later with Sasha, and Warren. This was greatly appreciated, because it is not obvious, and I might not have found it myself.

The track from the Water Entrance to the coast was in pretty good shape, and fairly easy to follow, but we left a few flags nevertheless. I cannot predict how long they will survive. Once down to the sea, we hiked along the Taylor's Hut road toward the Gun Club, stopping partway to watch a Nurse Shark hunting crabs in shallow water, about 10m off-shore. This was quite impressive (the first shark I had ever seen in real life), as it was at least 2m long, and had large dorsal and tail fins sticking out of the water.

Once back, we chatted for a few minutes with Bredda, and then headed out, reaching town about 9:00 PM.

With regard to georeferencing: Three points were recorded - Potoo Main, JBC 1, and JBC 2. Accuracy for all was good. The horizon was low, with many sats available, plus WAAS. The open question is the accuracy of the area map, as will be demonstrated in the report for Aug 8-9.

Many thanks to Adam for his help, and a big-up to Mike who did extremely well considering it was his first time caving.

Section of the JU area map with 2 of the 3 referencing points. Click for full size.
Section of the JU area map with 2 of the 3 referencing points. Potoo intentionally not shown. Click for full size.

Map of Jamaica showing the location of Portland Ridge. Click for full size.
Map of Jamaica showing the location of Portland Ridge. Click for full size.

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