Jamaican Caving Notes
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August 28, 2010
Schwallenburgh CaveOur explorations of Schwallenburgh Cave took place primarily because of the following entry in Jamaica Underground, from the JCC in 1963: "A sloping floor of mud and rocks ends in a pit of 65m with two small ledges. A large cavern below is blocked with guano."
August 22, 28, 2010
Team: RS Stewart, D Selvyn, A Haiduk
Notes: RS Stewart
Deep guano deposits serve as invaluable repositorys of Jamaica's natural history, but are now rare because of guano mining (used as fertilizer for ganja). Those few that survive are usually in chambers that lie at the bottom of deep shafts (e.g. Hulls Cave), or in chambers that are separated from the entrance by flowing or standing water (e.g. Rota Cave). Schwallenburgh sounded very promising. One concern was that it was located on, or close to, Windalco bauxite mining land, and may have suffered the same fate as many sites in St Ann and Manchester. That is, filled in or otherwise destroyed as bat roosts.
The location visit, by Donovan Selvyn and RS Stewart, took place on August 22. At first, the search was fruitless - it was listed to be somewhere on land that is now either part of the Mt Rosser bypass, or on the Windalco mining works, and there were no residents to ask about known caves. [On that, we had indeed heard of a cave in the district from people at the Faith's Pen food stalls, so had reason to think it might be Schwallenburgh, but most of them had only heard of it themselves, not been there. The one person who had was not available that day.] After about an hour of driving and hiking around construction sites and a partly-built highway, we at last got lucky by asking a man named "Troy" who we came across near the asphalt plant. He knew of it, and was quite happy to show us where it was.
The location was actually only about 100m from a place where we had looked earlier, but beyond a patch of thick, high, cane-like grasses. It took much chopping to get through this, and the entrance was thoroughly hidden behind - without the help of Troy, we would have never found it.
We were able to tell very quickly that we had the right cave - the upper part matched the map and description perfectly. About 30 minutes was spent figuring out how we would rig the pit on our return, and then we hiked back to the truck, and called it a day (Stewart had a badly-infected, swollen foot that would barely squeeze into a shoe, and he was in a fair amount of pain.)
An accurate GPS position of the entrance was taken, but because of the sensitive nature of the site, we are not posting the coordinates online. Also, there is a local name for the cave that could help in finding it, which we will not post.
On August 28 (Stewart's birthday), Selvyn, Stewart, and Andreas Haiduk returned to descend the pit. Our mode of entry was to tie the 100m 13mm rope around a large boulder, rap down about 10m of slope to the shaft, and then continue on vertical - one at a time, of course. Haiduk and Stewart were using racks, so had no problem, but Selvyn had somehow wound up with the smallest of our figure-8's, and simply couldn't move on rope. To deal with this, Haiduk went down first, tied his rack to the bottom of the rope, which was pulled up, and then Selvyn went down with the rack, and then Stewart came last. It must be noted that the "small ledges" mentioned in the JCC account are barely ledges at all - more like minor deviations in the wall of the shaft.
A description of the chamber follows: At the bottom of the shaft, a boulder slope continues downward on the north side. The first section is almost level, then drops steeply about 5m, and then becomes less steep until a boulder/talus choke is reached at the far end. It gradually narrows as it descends. The ceiling starts fairly high, near the shaft, and then lowers until it is only about 4m high near the end. There is no actual guano choke, at least not now (we saw no sign of disturbance that would indicate a change in conditions).
The guano is very deep on the west side of the descending chamber, and quite shallow in a thin strip along the east (which is where we walked). It is difficult to estimate the true depth because much of it might be sitting on breakdown boulders, hidden below, but it is at least 2m in places, and may be as much as 4m. This does not include sediment on the floor of the cave, only fluff and compacted guano. To investigate the nature of the guano, we made a small cut inward about 30cm, and the same wide, on the edge of the deepest section (a very small area of the deposit was disturbed - <1%). The vertical extent was about 50cm, although the guano extended down further (we were standing on top of a compacted strip along the east wall). The top layer is fluff, and then it becomes more dense until highly-compacted guano is reached at the bottom. The transition is gradual - no particular strata were obvious.
The thin strip along the east wall appears to be such because the cave occasionally takes water, probably during heavy rain, which erodes the guano deposited in that section. It is convenient in that it allows access to the side of the deep sections without causing damage.
The roost itself is not massive. We estimated numbers in the low hundreds, mostly/all Artibeus jamaicensis, above the top of the shaft, and perhaps 1,000 or less above the section at the bottom, which included species other than AJ, although the make-up is undetermined. The great depth of guano has resulted because of many years of accumulation, rather than great numbers of bats - as far as we know, this was only the second visit to the bottom of the cave.
No invasive roaches, P. americana, were seen (which is always the case with caves that have not been entered by guano miners - the roaches hitchhike in with the bags the miners use to take it out). Haiduk found a large, white isopod (>1cm) on the shaft wall that we've seen in other shafts, but never in chambers. Presumably, it's an accidental, although we have no idea why it prefers vertical walls.
Netting at the site will be best done with a mist net near the top of the slope that descends to the shaft (width is about 12m here). Outward of this point there is a large lighthole that probably also serves as an exit for bats (we have not been there during the emergence).
Sampling of the deepest sections of guano can be done with minimum impact by leaning an aluminum ladder against the west wall with the feet on the east. The estimated length needed is about 10m (this needs to be checked using the disto during a return visit).
Our exit from the cave was uneventful, although Stewart was somewhat slower on ascent than Selvyn and Haiduk due to the lingering effects of the infected foot.
On a personal note - the author of this report had a fine birthday party later at Pollyground, complete with much food, good music, and good company. During the course of it, he spent quite a while chatting with a very nice young lady he'd known for a while, who eventually became his significant other, thus making the day one of the best he has ever spent in the field.
An adaptation of the JCC (1963) map follows, with a cross-section G-G' added that shows where the deepest guano deposits are. Please be aware that the accuracy is poor in the lower section - it extends somewhat further than shown.
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