June 4, 2006
Team: RS Stewart, J Pauel, A Haiduk.
Notes: RS Stewart
The day before, June 3, our team had visited St Clair Cave. The plan was that if we managed to complete our mission at St Clair in one day, the next would be spent on the upstream caves of Riverhead and Worthy Park. This was the case, and on Sunday morning, June 4, after a nice breakfast at Marie's in Pollyground, we headed out to find the headwaters of the Rio Cobre, at Riverhead Cave.
On June 3, we had observed the normally dry riverbed of the Black River to be in flood (not to be confused with the one in St Elizabeth; this river is actually the top-end of the Rio Cobre), but we were uncertain if the waters were issuing from the cave itself, or a rising further downstream. The best approach seemed to be to follow the river upstream from a point where it was flowing, rather than trying to hit the cave from the highground to the northwest, where a road passes only 300m away. Accordingly, we followed the backroads from Pollyground that would get us to the nearest downstream section of the river, this being reached at a small bridge close to 18 09 21.8 N, 77 06 09.5 W, WGS84. At this bridge, there are two lanes, one on either side, that parallel the river in the upstream direction (west). We happened to choose the southern of the two, but this was found to swing left, away from the river, after several hundred metres. At this point, we got down into the river (which continued to smell of sugar cane, as it had further downstream near St Clair Cave the day before), and waded through it for some distance until the land on the other bank seemed to suggest a track, whereupon we climbed out on the north side and found ourselves on the extension of the lane that we had first seen at the north side of the bridge. This petered out in a coffee plantation, but access continued to be quite good for a couple of hundred metres further. At this point, a climb down into the river to follow the bank for a short distance got us to the entrance. In the last part of this, a very old, unused aqueduct runs along high on the north bank until a dam is reached at the mouth of the cave. The total distance from the bridge to the cave is 750 metres, and by using the lane on the north side, it can be hiked in under 20 minutes.
The entrance to the cave is moderately large and gives way to a chamber that is much larger. To the right, a boulder slope extends upwards for about 20m. The river passage itself curves to the left and is moderately high and rift-like, at least in its first section. We declined to enter this, because Riverhead is known to have noxious gases (waste-sugar input from Worthy Park), and we had already had a serious stint of that the day before at St Clair. From what we could see of the river passage, swimming would have likely been necessary in parts, and this seemed very dicey if we were to hit the low oxygen levels and high carbon dioxide that we had encountered at St Clair. Our main interest was to see if Riverhead was active, and feeding the Black River, which we had done. Investigations into the batroost and general biota of the cave could wait until dryer times.
As noted, there is a dam in place where the river exits the cave. The flow of the river may be guestimated by using the following numbers: a depth of apx 22cm where the water flows over the dam, with a width of about 6m. Andreas informs us that there is a formula that will work with those two parameters, with no need of flow velocity. [Video of the entrance in flood: WMV 1.6 MB; QT 5 MB; AVI 9 MB]
A return to this cave in the dry-season is high on our to-do list. The batroost that was noted by others in the past was identified to have the species P. aphylla amongst its members, and because of the great interest in determining if this species still exists, a rapid assessment of the extant biology of the cave is required. As for this visit, as the table included with these notes indicates, we could not really learn much.
The hike out from the cave was done entirely along the land to the north of the river, and went very quickly. Upon reaching the cars, we moved on to Worthy Park.
Before closing this account, I should note a humorous episode that took place: It was raining the entire time that we were carrying out the visit, and on the drive to the bridge, over wet, rough roads, I kept hearing occasional honks from the horn in Andreas' VW Beetle, in which he followed behind me. When this first happened, I stopped, stuck my head out the window to check, and Andreas with a grin informed me that "it's alright, it's automatic!". Moisture in the wires, no doubt. On the drive back out, this again took place, with Andreas now ahead of me, but added to this was the car alarm in Jan's SUV, regularly squawking/whooping/etc, as he drove behind me (also because of the rain, I believe). At any rate, we covered a couple of kilometres preceded by the beeping of Andreas' horn, and followed by Jan's car alarm, with me in the middle listening to the resultant concerto (I kept the stereo off so that I could best enjoy it). I imagine it was equally entertaining for others who might have heard us go past, and we certainly didn't have to worry about anyone coming around a corner and running into us.