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Apr 4, 2004

ROTA SINK


Position: WGS84 - 18 21' 09.8" N, 77 47' 56.3" W, +/- 10m

Field notes: R. S. STEWART

Cavers: R. S. Stewart, G. van Rentergem, I. C. Conolley, M. Taylor, M. Bellinger.

Time in: 11:30 EST, Time out: 16:30 EST

THREAT VULNERABILITY: High

A return to Rota Sink was high on our to-do list this session; it would be our first opportunity in a year to explore the cave when the chance of flooding was low. To get to Rota Sink, we had decided to make the journey by way of Peterkin Cave and Rota Cave, the first two, of the set of three, that comprise this system. We would do this for two reasons: firstly, it would be a nice jaunt through the underground, and secondly, we would reach the entrance to Rota Sink faster than by attempting the confusing overland route with its myriad of intersecting paths through the old agricultural land of Maldon.

Well before noon, the crew reached the usual parking spot on the road above Peterkin Cave, and we were soon entering the westernmost of the entrances. I will give an overview of the Peterkin/Rota system as I describe our travel on this day.

The waters of the wayward Tangle River, in one of its incarnations, enters Peterkin Cave at the western end. It does this underground during the dry season, and when it is rainy, surface waters will also enter by way of pasture-land to the southwest. It is at these times of heavy rain that much of the garbage to be found throughout the system enters, by way of rafting.

When one goes into this western entrance to Peterkin, a large passage will be found that leads across boulders to a pool of some 15 x 20 metres. This pool can be crossed by either swimming through the middle, or by staying close to the south wall where it is possible to wade, albeit chest deep. Once past this, a smaller passage leads to a sump where the river continues, submerged. Soon before this sump, a large slope of flowstone is found on the right side, (east), that ascends up into a breakdown chamber. The flowstone can be climbed using bouldering techniques, and at the top, to the left, (north), a crawl through a low, wide, muddy extension leads into a higher, dryer, section of the cave. From here, one keeps to the left wall of a long breakdown chamber until daylight is seen at the very large east entrance of Peterkin cave. Rather than exiting completely from this, one must go down to the right, (southeast), and pass through another small cave, (some 35 m long, 15 wide, and 7 high), to exit on the side of a hill, at no great distance from the west entrance to Rota Cave. Seventy metres away, at a bearing of 60 deg true, a seasonal stream-bed leads into the west entrance of Rota Cave.

We had main good time through Peterkin, following the now familiar route described above, and were soon ready to enter the next part of the system, Rota Cave. After a quick stop to double-check the previously obtained GPS position for Rota West, we headed underground again.

Once into the entrance to Rota, a scramble down over boulders lands one in shallow water, that is to say, shallow in the dry season when it is possible to enter the cave without dying. It will be noted by visitors to the cave that this entrance passage, of about 8 metres in height, shows debris, such as bamboo leaves, sticking to the walls right up to the top. During the rainy-season, this entrance passage floods to the roof. It now being early April, and safe, one merely wades along, to the south, through a decent-sized passage, (about 8 m wide, and 8 high), for several minutes, until one hears the river flowing through the main passage ahead. A couple of minutes more, and you once again reach, flowing past, the underground river that had sumped in Peterkin Cave. This T-junction, into the large, main river-passage of Rota, offers two choices: upstream, to find where the river enters, or downstream, to eventually exit at the east end of the cave. Downstream, and out, was our route, for we were still on our way to the main target, Rota Sink.

Downstream in Rota Cave, one wades through the river at times, and when deeper water is reached, one scrambles on rock walls on the south side. The river passage remains large the entire way and leads one directly to the eastern entrance. Before this point is reached, large breakdown chambers, not indicated in the existing map, intersect the river passage on the south side. These large breakdown chambers, apparently not mapped by Bristol U because they were not hydrologically significant, house a very large number of varied species of bats. I took the opportunity on this visit to make a quick foray into these chambers to observe the bats, in particular their current estimated numbers, to see if there was evidence of a seasonal decline as observed at Thatchfield, the week before, and reported by Susan Koenig, at Windsor. Interestingly, the numbers seemed as great as ever; Rota does not seem to be experiencing the same seasonal cycle. This done, I led us out of Rota Cave and on to Rota Sink.

We had only visited Rota Sink once before, during a time when rains prevented us from going very far into this final section of the Peterkin/Rota system. The GPS position obtained during that previous visit allowed us to re-find the entrance without any great amount of time being wasted, and soon after leaving Rota Cave, we were scrambling down into the large entrance chamber of Rota Sink.

At first, to look at the drop into the entrance chamber of Rota sink, it appears that vertigear is necessary, there being a vertical of about 10 metres with no obvious climb down. But, if one looks carefully, a scramble down through rocks will allow one to easily reach the bottom without need of a rope. At the bottom, a beautiful chamber is reached. The waters of the Tangle River enter underground, from Rota Cave, through horizontal fissures in the wall. They then splash through rimstone pools, and flow into the main river-passage of the cave. This passage, 4 m wide and 4 high, is entered at the northeast side of the entrance chamber. It begins with a swim across a pool some 10 m wide, through very cool, refreshing water. Our crew, a very solid, experienced team, had at last reached our goal for the day; we began to launch ourselves through this water, to explore Rota Sink.

It should be noted that this cave is in no way a sink. In fact, it is as far from being a sinkhole as one can imagine. The waters arrive underground, the entrance is via the top of a breakdown chamber high on a hill, and the development is horizontal. It continues the underground flow of the Tangle River, en route to Springvale, and flows year-round.

On this visit, Ivor pointed out a large piece of bamboo that had been rafted in during the rainy season, lodged in rocks some 12 metres above the entrance chamber floor. This cave not only floods to the roof, it pools up like a standpipe where head-room allows. Rota Sink cannot be trifled with... at the wrong time of year, if you go in, you will die. This was not the wrong time of year, so one by one, we swam across the first pool to venture into what was for us new-ground.

I headed in for the swim first, finding the water temperature quite nice, in fact much warmer that my pond in Canada ever gets, even in July. Once across, the others followed, not perturbed in the slightest by the swim itself, but all noting how cold it was. Guy and Ivor came across without the use of life-jackets, as we only had three for the five of us, but they seemed to have no problem. I confess, I hadn't even considered this, and had neglected my duties as the supposed guide by forgetting about it until they had reached where I was, on dry ground at the far end of the pool. It had been in my mind that we could use a 30 m rope, that we had with us, to shuttle life-jackets back across to them, but however it happened, they made it without the use of flotation devices.

I had expected the river passage of Rota Sink to be low and muddy... it wasn't. It is wide and high, and is a testament to the great flow of water that blasts through this cave during the two rainy-seasons every year. We followed this magnificent passage for several hundred metres, sometimes out of the water, but more often in it, until finally the river sank through breakdown boulders to disappear below us. It was in this section, while scrambling over highly eroded rock, echinolith, that I had two of my three points of contact suddenly let go at once, and I found myself dangling by one hand, with my other limbs sliced somewhat by the sudden fall. At the time of the writing of these notes, they have all finished healing, but I must once again give thanks to Jah for ensuring that all of my accidents are minor and serve only as a good reminder of what can happen if one is not careful.

The Tangle River finally goes missing, in Rota Sink, under boulders in a breakdown chamber, about 350 metres in from the entrance chamber. At this chamber, to the right, it chokes. To the left, a large muddy passage continues. We followed this, and soon reached another Y-junction. To the left, the passage drops into vile, pooled, water that bubbled methane as we walked into it. We decided to take the passage to the right. This passage, like the other, experiences limited seasonal scouring, it serving as an overflow for the main river. As a result, there is heavy deposition of silt during the slow draining of the waters at end of the rainy-season, and it is very muddy. It is about 2 m wide, and 3 high, and after some 15 metres drops several metres into a lower, muddier part. There was some concern as to whether we would be able to re-ascend this muddy pitch, but Guy, brilliant, fearless caver that he is, scrambled down anyway. I soon followed.

At no great distance from this scramble, we again found a Y-junction, with both branches low and very muddy. Guy took it upon himself to crawl and slither into the most likely-looking of the two, and forged ahead. I stayed at the junction, being not too keen on getting into the mud if someone else were willing to do it. After 10 or 15 minutes, Guy returned. He had found the last Y-junction that showed on the JU map, and had a look at both branches. It seemed as though it was not encouraging for a way on, (but I look forward to reading his notes on this). We thusly called a halt, hauled ourselves up the muddy pitch above us, and began to make our way out of the cave.

The trip out was without incident, but when we were again above-ground, we were faced with a decision: return via Rota Cave and Peterkin, below-ground, or attempt to find our way out through the confusing trails above-ground. We chose above-ground. The usual wrong turns, consulting of GPS and compass, were done again, but we had much better success this time. There is a slim possibility that Malibu and I might be closing in on learning the various trails that criss-cross this part of Maldon.

The hydrology of this system is thus: Peterkin Cave is the upstream section, and because it has surface flow into it, through pasture-land during the rainy-season, it has much garbage and is polluted by cow feces. At the Peterkin sump, the passage continues, submerged, with a large enough cross-section to allow the garbage to flow underground into Rota Cave. At the downstream end of Rota Cave, where the river disappears though sponge and fissures, the garbage is filtered out and is concentrated in the final passages. Rota Sink benefits by having its waters issuing into the cave through fissures, and because the only entrance is some distance from the nearest houses and roads, it is fairly pristine. Nevertheless, the cow feces that enter via Peterkin pollute this continuing river, and continue underground to rise at Springvale, as polluted as they started. The waters are not filtered through sand and gravel; they run through passages and fissures. The upstream catchment should not be pasture-land... it should be put back into forest.

The map that follows, done by Bristol University in 1967, is to be seen as more of an advisement than a true rendition of the system. Rota Cave, in particular, is not accurate. Not only does it not show the main roosting chambers, the section shown from the main T-junction to the east entrance is about 80 metres short. The Bristol University crew did splendid work, but they were pressed for time, and were trying to do initial maps for many caves, and were not able to map things as accurately as they would have preferred. We'd like to offer our deepest respect for what they accomplished, and we hope that they don't mind us posting their map.

Adapted from Bristol University by way of Fincham

Map scanned from Jamaica Underground, Alan G. Fincham. Survey by the Bristol University Expedition of 1967.


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