Hang Khe Dung
Geologylesson 1.01; from the Mendip guide to cave exploration: "Theresbees two types of rock; cave bearing limestone and tother shite"
It was uncomfortablyhot as we left the roadside of the Ho Chi Minh highway. We were accompanied on our march to the sound of distant thunder in the mountains. Oursmall teamconsistedof Deb, Mr Kyand his gang of 4 porters, a national park ranger & myself. With an objective to check out a small stream sink in the valley next to Hang KheTrieng (AKA Trevor’s cave).
It had been a late start to the day, supplies, porters and transport being sourced and organised in the morning, we now had a leisurely walk down to the Doong River for our evening camp at the base of the first ascent, ready for a long haul the following day. Our unhurried pace allowed ample time to fit in a spot of crab hunting and BBQ at the first stream crossing, followed by afternoon tea at the Doong minority village and rounded of by a spot of drag net fishing for our supper in the main riverbefore retiring to our hammocks in the warmth of the evening sun, life's tough at the sharp end of speleology.
Dawn start, and the first ascent for a rude awakening. We followed a hunters trail up over a steady hill and dropped into the adjacent valley. A dry wet season river bed provided a virtual motorway into the interior. Travelling upstream we eventually reached a set of pools at the base of a steep 'perfume tree harvesters'path,wherewe replenished our water bottles in preparation for the day’s main event. Mr Ky advised us that the cave and camp was just over this hill. Great we thought, and asked how long it would take? "Six hours"! Not quite the answer we had hoped for. We climbed, we toiled, we crawled, we sweated, we plodded, we fell over, we staggered, we scrambled, did I mention we sweated, throughbamboo crawls, rattan traps, 36 degree heat, no shade, loose scree and tornado felled trees and always taking a near vertical direct line for the summit peak. At the top we were relieved to see that we would not be climbing any higher today, as we were on the highest peak for miles. To our relief the descent down the other side was not at the same gradient, which bode well for the journey back. Eventually wecrashed out of the bush into a wide valley with an active stream bed strewn with flood felled trees. We set up our hammocks a on a gravel bank a couple of hundred metres upstream, near a convenient crab catching pool, and set about preparing a late lunch. Fed and watered, and armed with survey gear, we set off to investigate our lead.
The stream bed led to an uninviting rotting log jamb (an entomologists paradise) disguising the active stream sink. We crashed through the detritus and climbed down into a very black conglomerate maze. Choosing a route through the multitude of small tubes was made easy by an incredibly strong draught whistling into the cave (we later discovered it was not so easy relying on following the draft to negotiate the conglomerate maze in reverse). We picked up the stream and followed it through a complex series of tubes until it sank into a boulder collapse. Steep walled boulder run-ins on the left of the passage became a reoccurring theme in the upper sections of the cave, this left us nervous that our trip would be cut short by an impenetrable boulder choke. We regained the solid passage and noticed that the conglomerate became lighter in colour and resembled a mosaic of differing types and colours of angular stones set in light grey cement. We continued along a zig zagged section of parallel tunnels, the last of which was stunning. The highly textured mosaic walls stopped abruptly at floor level, and met a smooth curved & undulating bright pink floor, it looked bizarre, and neither of us had ever seen a passage like it. We dropped into another complex of interconnecting passages within rock that resembles scabbled concrete. From this point on the cave started to grow in stature as we reconnected back to the stream.
We froze in the strong draught as we swam across a brace of deep pools. Exiting the wind lashed swims we were able to warm up in a large square railway tunnel sized passage. This section of cave was extremely photogenic with its roof decorated with shields of stal and marbled calcite and green pools. We encountered a boulder run in from the left and the roof rose in to blackness, andour lights soon revealed a large chamber. A large inlet stream emerged from the left wall of the chamber; unfortunately we could only follow this passage for several metres until a deep blue sump barred the passage.
We continued through the chamber climbing over a huge breakdown boulder pile to the edge of a deep precipice. We were looking down a massive tunnel with the stream rumbling 20m or so below us at the base of a very steep boulder slope, with no obvious way down. High up on the right a well decorated passage/grotto could be seen, unfortunately ropes and protection were required to gain access. Our immediate concern was how we were going to safely descend down to the stream way so we could continue exploring along the enormous passage. Our investigation found a small vertical squeeze under a van sized boulder, which provided a precarious descent to a rock ledge which allowed a safe access down to the stream. We did find it somewhat ludicrous that we were digging out a loose vertical squeeze in a 40m x 40m wide open railway tunnel. We continued to follow down a series of climbs with the cascading stream below along a remarkable passage with somewhat unusual and striking with flat horizontal pink roof, vertical square dark red walls, cream coloured floor and turquoise pools and stream. We followed the passage to another large chamber with stream thundering through. We turned around at this point and headed out photographing as we went.
The following day we continued from the chamber downstream along the massive passage. It wasn't long before ourhearts sank as the passage appeared to close down completely and end in a large pool. Swimming across the pool, a low arch revealed a sharp turn in the passage with the continuation of the stream following a deep canal "Sign of Zorro revisited". After a long cold swim the passage regained its grandiose stature and charged off again into the hillside. The massive rectangular passage continued, and was intercepted by another high level inlet coming in from the left. We suspected that we were close to the surface, as the passage became littered with decaying vegetation and the air was filled with swirling bats overhead.
The huge passage again swung to the left and took on a different character, and the stream funnelled into massive silt covered boulder pile, the passage looked to continue wide open at high level, but due to the steepness and severity of the near vertical mud coated walls; we dismissed it as a plausible route to glory. Our focus turned to the complex boulder choke and an attempt to trace the stream through the blockage. After an age of dead ends, blind alleys and dodgy voids with in the rock pile, we retreated and took a second look at the high level passage. Our initial thought was to scrabble up the slope for a better view; this was easier said than done. Combined tactics and got Deb to the top of a muddy 45 degree arête allowing a scramble to the top of the 6m climb. However, getting the next person up and both down again was going to be dodgy. To overcome this obstacle a ladder of steps was hewed into the near vertical mud slope using a karabiner. With the climb safely negotiated we found ourselves perched on an obstacle course of steep muddy arêtes. Legs straddled either side of the knife edged ridge, we tentatively crawled between 8m deep precipices on 80degree mud slopes, whilst cursing leaving the rope back in camp. What goes up must come down, this involved a slide of faith, then reversing the slide by cutting more steps to ensure it was reversible before both of us committed to the slide and the open passage beyond.
We followed the stream along a stooping silt lined passage that had the feel and look that it spent a significant part of the year submerged. We stumbled around a bend and encountered a deep emerald pool. Our discussions immediately turn to "it must be a sump! Doesn't look hopeful, Looks cold! Time to call it a day, we better just check it out, just in case". Deb took the lead and swam off in the direction a low arch, and causing mayhem to the local white fish population. Shouts of "It goes" filtered out from the archway, signalling another succession of floating survey stations. The canal took a sharp turn to the right, and after several survey legs we beached on a shingle bank in large rectangular passage. We stormed off surveying in the vain attempt to warm up after the long swim. This plan was thwarted when the passage turned 90 degrees left and immediately the roof descended deep into a turquoise sump pool. A swim around the pool failed to reveal any sign of airspace and confirmed the end of our exploration. Amazed at the distance we had travelled underground without encountering any limestone, we beat a steady retreat, ensuring we captured a photographic record of the cave on route, and checking that no obvious side passages had been missed.
Extremely happy with 1.5km of sandstone cave tucked under our belts, it was time to end our foray into the “hills of other rock" and embrace the demanding nine hour walk back to base, in time for aperitifs at cavern bar.
Cu Tom, Vuc Cu Tom, Hang Cu Ton 2, Wet Rift Resurgence
Martin College, Steve Woods and myself spent 3 days upstream of the river flowing past Ruc Caroon, the once full-on, bone-shaker of a journey tamed by a vastly improved road. The village’s former sense of extreme isolation has been exorcised following it having being re-built, on a grid system, as a larger, uniform, settlement complete with café/store, school and communal village hut. Nowadays the village elders, patriarchal spokesman, rounds of rice wine toasts, suspect food and hours of talk around permissions and guides are replaced by Khanh’s 30 min disappearance followed by a trek down to the river and desultory waves to the only vaguely interested villagers.
Turning upstream, the left-hand bank was followed for some 90 minutes or so before fading daylight and a thunderstorm forced an attempt to make camp shortly abandoned as a better site was found a further 20 minutes upstream. This extended trek crossed an obvious resurgence (left-bank, upstream), “Wet Rift Resurgence” which we would look at two days later.
The new campsite was particularly pleasant. Open aspect, sandy beach, wide river complete with swimming and a dry crossing point. Idyllic.
Hang Cu To + Vuc Cu Tom – 14th April 2014
Crossing the river to the right-hand side, a steep valley ascended to the first of the two new caves, Hang Cu To. A very large and exciting looking depression was descended via a corkscrewing, and heavily vegetated, path on the left-hand side. This levelled off into a large, desiccated 20m x 20m chamber complete with obligatory bat roost and connecting chambers of a similar size. Despite its obvious looking promise, the cave quickly closed down after approximately 200m of surveying with no sign of any obvious leads, water or drafts.
Back to top of the depression and a further 20 min walk to Vuc Cu Tom. Now this wasan exciting looking lead! A straight 20 – 25m pitch into a huge depression complete with its own dense foliage. Perhaps indicating its potential, in Son Trach Khanh had flagged he would want to accompany us down the cave and hence we had packed a complete spare SRT kit. As the pitch would necessitate a rebelay over the lip, initially we tried to dissuade him from going down but quickly realised the potential loss of face, or any failure on our part to encourage his obvious enthusiasm, might ultimately prove counter-productive. Instead we decided to use two ropes on the pitch and a safety tether between Khanh and myself.
Unusually I had failed to pack my foldaway saw so clearing the bushes over the lip had to be addressed with a porter’s machete. Lowering down a couple of meters and locking off before wildly swing a sharp machete close to the now tensioned rope caused wild fluctuations of amusement and panic across the faces of the Sherpas. Finally rigged with two separate tree/sling re-belays, all descended without incident.
The bottom of the doline was an impressive 100m x 100m, the greenery becoming denser towards the middle with increasingly larger boulders peppering the floor. A general decrease in available sunlight however meant that where the walls met the floor; a reasonably easy path could be circumnavigated around the entire perimeter. Unfortunately, other than a side chamber and bat roost, there was little of interest. A quick thrash into the centre of the bowl-shaped floor failed to find any ongoing passage/leads despite signs of a wet-weather stream. Disappointing as the cave had had such initial promise but hey ho, such is the lot of exploration caving and at least Khanh seemed to thoroughly enjoy himself.
Hang Cu Ton 2 – 15th April 2014
The next a day, a return along yesterday’s route before branching of to the right led to Hang Cu Ton 2, a 30m elliptical cave entrance with no obvious continuation. By now Martin was struggling with illness and a return to camp for an afternoon’s reading and relaxation was in order. This turned into a high-level Tyrolean, Passé bloc, rigging exercise 10m above the river to the delight of the Sherpas who took turns in being popped into harnesses and crossing back and forth.
Wet Rift Resurgence – 16th April 2014
The mighty machine that is Martin Colledge had now ground to a halt. Sickness meant Martin needed a day in camp. The Sherpas remaining new cave increased in a distance from camp from 2 to 5 hours. With this in mind, Steve and I instead decided to visit the downstream resurgence crossed on the walk in.
Water flowed out and various, presently dry, overflow spots could be seen in times of wet weather. Starting at the nearest spot to the river, smashing through cobwebs we slid between a narrow 1m x .5m gap in the boulders into a hand & knees stream passage. Looking narrow, dangerous and unpromising, we decided to abandon any attempt to survey but instead have a look to see if it went, the expectation being that in all probability it would quickly choke. Unfortunately the cave had other intentions.
The first 50 or so meters was through sharp, fallen boulders, a combination of ducks, hands & knees, sideways rifts and rifts leading occasionally to daylight through roofs of hanging death. A 100m ish, the cave turned into a dark but solid 1m x 1.5 rift. By now our Ronnies and t-shirts had developed numerous slashes and holes as the sharp rock took its toil. Ducking face down above stream level as a squadron of poo-bombing bats swarmed overhead, we decided this pesky cave was unfortunately still going and therefore did need surveying. A cautious exit was made to sunlight whereupon Steve turned and asked if I’d mind if he didn’t go back in? Trying to mask my exuberance, stoic faced I agreed it wasn’t a problem and we scampered back to camp with only a jaunty whistle playing across my lips and a spring to my step hiding my deep, deep disappointment.
So sorry, Wet Rift Resurgence still needs a second look and a survey team. In all fairness it is heading into a blank area of hill and was getting better but probably isn’t worth a visit for its own sake. It’s low, broken, wet and sharp entrance series isn’t your typical Nam cave being more akin to something situate in Foxup & Cosh. It goes without saying that the crawl through the entrance series boulders should be treated with caution.