Cave River - Border Hole
May 8, 2007
Team: RS Stewart, J Pauel
Notes: RS Stewart
South Entrance: 18 13 13.1 N; 77 23 58.8 W - WGS84
North Entrance: 18 13 17.1 N; 77 24 01.3 W - WGS84
Tuesday, May 8, was our second day spent investigating the Cave River System. On Monday, the River Sink and Top Hole had been visited, which, amongst other things, had given us two known points for the KHE map from 1965, and allowed us to determine rough locations for the other entrances of the system.
In the morning, over coffee, I'd used the map to work out a distance and bearing for the entrance to Border Hole, in relation to the south entrance of Top Hole, for which we now had a GPS point. Once we'd hiked to the general area, I set the GPS to navigate to Top Hole, and thus had a constant display of distance and bearing. Using that, we hiked in the direction that would put us at the determined distance and bearing for Border, and it was soon found, within some tens of metres of where we expected it to be.
To the south of the entrance to Border Hole, the river rises from True Sink, and flows aboveground for about 30m through a section of collapse called Bamboo Trench, until it passes below very large boulders that obscure the entrance to Border, where it again goes underground. The route through the boulders to reach the entrance is not easy - at first, it seems as though there is no entrance at all, and much scrambling is required to get past the first set of large boulders that hide it and block the way (we used a 9mm line in one spot). Those who look for the site using our coordinates are advised to not give up the search too quickly, thinking that they're in the wrong place, and to refer to the map that accompanies these notes.
At the base of the entrance scramble, a wide section of passage is reached through which the river flows. After about 150m of wading and swimming, a collapse entrance is found on the right (northeast) side. We noted it and carried on deeper into the cave. Soon, the passage narrows, and one must swim more frequently. Along with the swimming, it is necessary to scramble along echinolithed walls at times, as the passage steps downwards in a series of short waterfalls (quite nice to look at). After a few hundred metres, the river sumps to the left, with a separated, stagnant, garbage-filled pool of still water to the right. This section only takes water when the river is higher, and during our visit was not sharing water with the main passage itself. We swam through the mess (with Jan out front), and reached the end of it after about 20m. Now, we began our return to the second entrance we'd noted on the way in.
Surprisingly, the second (north) entrance is not indicated on the KHE map (I have added it to the map that's atached to these notes). This led to some confusion on our part at first, causing us to wonder if we were indeed in the cave we thought we were. After the expedition, when we georeferenced the KHE area map using our GPS points, we were able to see that it matches a feature shown on the Border map that indeed does indicate a collapse, but neglects to note the associated entrance.
After reaching the second entrance, we decided to attempt the scramble out so that we could georeference it, and find a track for it aboveground. This would prove to be somewhat nerve-wracking. The entrance, like others in the system, had bamboo growing immediately outside, and the scramble to get out was up a steep slope about 15m high, on mud-covered rocks, with a layer of leaf-litter and much dead bamboo on top. Jan went first, and gingerly made his way about two-thirds up, followed by me. Here, we stopped to try to find a safe way to carry on, and as we did, I noticed something moving out of the corner of my eye. Looking, I saw a rat running by about 30cm from my feet. As I do not care for rats, I was startled and jumped about a half-metre to the right. This in turn startled Jan, and we both came very close to sliding back down the steep slope onto the rocks below. With this bit of panic out of the way, Jan carried on, very carefully, until he was at the top and on safe-ground. I followed, kicking steps as best I could in the mud, concerned the entire time that they might let go as I put my weight on them. Fortunately, they didn't, and I was soon with Jan. After taking a breather, I ran the GPS, got a good position, and then we easily found our way back to the route that had taken us to the first entrance, this through scrubby, poor, pasture land.
The passage itself has two notable features: First, there is a substantial section of phreatic pipe, which was not seen elsewhere in the system. The cross-section is circular, with scalloping on the walls. I believe this is in the section between the two entrances, but I did not note the location specifically on my fieldsheets. Second, the water in the passage is very warm, as it has spent little time underground upstream of Border Hole. It sinks near Aenon Town, comes out aboveground in the section before True Sink, and then again at Bamboo Trench, and has only been underground for about 200m before it reaches Border Hole. Before it reaches the first sink, the river is wide and shallow, and flows for a great distance, allowing for much solar heating. In fact, it is so warm that in the first section of Border Hole (in the phreatic pipe, I believe), the water was steaming, as warm water travelled through the cooler temperature of the cave. This was quite interesting to swim through and leant a rather surreal quality to the experience.
In the other sections of the cave, downstream of the north entrance, the passage is relatively narrow, and as with much of the rest of the system, runs through pure echinolith. This highly-eroded, sharp-edged, native rock makes travel very slow - one misstep, if it results in a fall, can cause great harm.
Siltation is great throughout the cave, with large accumulations at the turns in the section between the first and secnd entrances. It consists of both sand and silt. The sand input is from the Cave River sources in the non-calcareous central inlier, the Black Grounds, to the northwest. The silt component is topsoil made available by agriculture, which is common immediately upstream. There is also highly localized input at the south entrance, as a result of farming directly adjacent to the entrance on the west side. During our visit, a section of soil on the collapse slope to the west, about 2-3m wide, was actively slumping downwards.
There is much trash in the cave, consisting of plastics (buckets, bags, bottles, etc), rubber (boots, tyres), and polyurethane (insulation). Evidence indicates that most of it is coming from the River Sink, that is, the start of the system in Aenon Town. During our visit to the sink on May 7, we observed solid waste floating in the water, and also caught in the build-up of bamboo and other organic material accumulated in front of the entrance to the sink. We also noted that dumping was common in the river upstream, as well as the gullies that feed into it. We did not see any notable input of trash at the two aboveground sections between the River Sink and the entrance to Border Hole. We believe it to be certain that the main input of solid waste to Border Hole is from the River Sink.
There is a considerable accumulation of solid waste at the downstream end of Border Hole, in the overflow pool (it's difficult to quantify it, but it's roughly one piece of floating garbage per 1 sq metre). This indicates that the solid waste is reaching the end of the cave, that is, where it sumps and human access is restricted until it rises again in Top Hole. We observed much trash in Top Hole during our visit on May 7, and the main input, as with Border Hole, appears to be the River Sink.
The fauna of the cave consists primarily of invertebrates (other than fish, see below). No bats were seen. Much of the cave floods to the roof in heavy rains, especially downstream of the second entrance, and in those sections that are somewhat dryer, such as the old phreatic pipe, the roosting space is poor, consisting of very shallow scallops. However, there may be seasonal occupation in the area of the two entrances, at least by Artibeus.
Fungal gnats and associated predators were not common, due to the absence of bats and accompanying guano deposits. No cave-adapted spiders were seen, although they may be present, but not in great enough numbers for us to have easily seen them.
Neoditomyia farri were present. This is a predaceous fly larvae common in Ja river caves that constructs a simple hanging "web" to snare flying prey. It usually consists of a slghtly drooping horizontal thread, 5-15cm long, from which fall many fine threads, up to 20cm long. The larvae are about 1-1.5cm long and 2mm wide, and will usually be seen on the horizontal, main support thread. Apparently, their required nutrient input is low, because they survive in areas with little prey, and seldom have anything in their snares when you see them in a river cave. For those who may come across them, it should be mentioned that the thread construction is very fragile, and can be destroyed by simply breathing on it. This will not kill the larvae, but it will force it to expend more energy to rebuild it, with the prey capture rate possibly not enough to support the extra output.
The invasive roach P. americana is present, but in low numbers. The nutrient input is rafted detritus, rather than guano, with this limiting the population.
The aquatic faunal component consists of at least one endemic stygobite (Sesarma verleyi), several species of opportunistic fish common to the river external to the cave, and one invasive freshwater species, the Australian Red Claw. The Red Claw has the potential to be very damaging to the original aquatic species in the cave, and it will be addressed separately in the NEPA report for the Cave River System.
Please be advised that there is a serious flood-risk in the section downstream of the second (north) entrance during the rainy-season. Do not enter this part of the cave during times of regular, heavy storms, especially if the water table is already high.
KHE Map via Jamaica Underground.