March - 2019

It is often the case that caves are more difficult to re-locate than they were to find in the first place. It has been said that entrances ‘heal-up’ if they aren’t used but it is certainly true that the discovery of a new cave requires a degree of luck.

The Search for Blackrock: Matt Kirby, 2003

Northern Api has tantalised explorers for many years. The southern extremities of the mountain have revealed a labyrinth of passages on many levels, but a large blank area of limestone remains between Blackrock Cave and the Melinau Gorge. It has always been hoped that a continuation of the single minded passages of Benarat’s Tiger Cave would be found in G. Api, on the other side of the Gorge, leading to caverns measureless to man. Unfortunately this has so far proved elusive.

Richard Chambers and I arrived at the mid point of the expedition. We were ‘Api veterans’ and this was the first time we had been based at Camp 5. We proposed to investigate the area between the Melinau Gorge and Blackrock Cave; an aim which led to a monstrous hiking challenge and Mulu foot.

Initial intentions were to head southwards from Camp 5, following the base of the cliffs, eventually to reach the Racer entrance of Blackrock, a distance of 4km. Clearly this would take a few days and past experience had shown that it would be an ‘interesting’ challenge.

Talk of a ‘large entrance’ just off the pinnacles track led to a detour up the slopes on day one. Traversing to the south revealed that large cliffs, which make horizontal progress impossible, intersect the side of the mountain. Following a series of difficult scrambles down tree roots it was decided to take the easier route at base level but the fabled ‘Large Entrance’ was unfortunately not to be found. After a couple of hours a minor cave/overhang was discovered containing a small colony of bats. Another entrance was found just round the corner. The nature of the rock in this area was strange, appearing to be a conglomerate of broken limestone. Neither cave merited a survey.

Progress led into a valley with the slopes to the east at a fairly easy gradient but the going became more difficult as the route led onto karst terrain. After a battle around and through some large tree fall, on steep ground, a col was reached. From here the slopes eastwards appeared to form a gentle rise up to the bulk of the mountain. The large white cliffs above the northern end of Blackrock could be seen on a bearing of 121°. Owing to the difficult nature of the route in, and with a certain amount of curiosity, it was decided not to retrace our steps back to Camp 5 but to head due west in the hope of finding the Camp 5 track which we did at the 6.8km point. From the col the ground rose up onto alluvial fan deposits and generally the going was fairly easy. Another fairly insignificant cave entrance was found. Once again this was in the conglomerate material.

As the transition from the alluvial plain to the foot-slopes had been found to be fairly indistinct it was decided to try a direct approach to the mountain side from the Camp 5 track, with the hope of finding Racer entrance. This was a direct distance of 1km.

Prior to the arrival of the expedition in Mulu, exceptional rainfall had caused the Melinau to change course. This meant that the Camp 5 track now involved two river crossings, as the central section had become a four-kilometre long island. It later transpired that this new channel had been the course of the river at the time that the RAF took aerial photographs of the area in 1960. This proved very useful in subsequent identification of features. It appears that the Melinau regularly changes course between these two channels.

It was decided to follow the track south to where the river had changed course, then cut due east. This proved disastrous as the ground is low lying and has been subject to frequent flooding, leaving a tangle of impenetrable secondary forest. The attempt was finally abandoned when we hacked ourselves into dense rattan which transpired to be the home of millions of stinging fire ants. The nature of this type of terrain is almost impossible to describe – there is never an opportunity to see ahead in order to determine a best route, so it is simply pot luck whether a clearing is found. Thwarted by ‘rattan alley’ we headed back to the river after making only 50m progress in more than an hour!

From the river crossing, the cliffs looked tantalisingly close and so a second attempt was made from 100m downstream. Once again dense secondary growth prevented progress. It was clear that finding a way to the mountain side from here was a total waste of time.

In order to make the best of the day, a drastic course of action was taken – to head for Kuala Lutut and to try to re-establish the old track to Leopard Cave. We headed off in the hope of finding some evidence of the old route. Alas this had long since disappeared and so new route finding was required. This proved successful, however, Leopard Cave was much further south than we wanted to be, so this route-in to the target area would require a considerable round trip of 22km.

Diary entry
“After 1.5 hours we were still only about 150m from the river – ho hum, try Plan B… So we used up the rest of the day walking to Long Lutut and tracing our old ‘91 path to Leopard Cave. How we ever camped at Leopard for 3 weeks in ‘88 must be a question mark on our sanity – but I suppose that being here again, 15 years later, just confirms that!”  Richard Chambers

The nature of the ground between the river and Leopard Cave is varied. The track had been established by Penan before the 1988 expedition and generally followed easy ground. However, Europeans don’t have the same knowledge. On the way in we discovered that a line of karst intersects the route. A tortuous route was found through this, which led onto higher ground before dropping back to swampy terrain north of Leopard Cave. At no time had any evidence of the original track been found nor any feature been recognised. As light was beginning to fade it was decided to take a bearing from Leopard Cave back to the river and try to find evidence of the old track from that direction. Once again there was no trace and indeed we crossed our own inward track without noticing it and managed to reach the river north of Kuala Lutut without even finding the band of limestone!

As the route in via Leopard Cave was now open, it was decided to return carrying bivvy gear and with the intention of locating Racer entrance and pushing known leads. What a silly idea!

We returned the following day with Olly. On this occasion we managed to get completely tangled up in the karst band. In fact we had hit it slightly further to the south, where it forms large pinnacles and canyons, which sap the strength and drain all remaining fluid from the body. Much thrashing about ended in a complete retreat and change of direction further to the north. Fortunately, this led onto the previous day’s track through the limestone barrier. After fire ants had attacked Olly, the group reached Leopard Cave. Northwards the trail was fairly straightforward as it generally follows the side of the mountain. Again there was no sign of the 1988 track, so it was necessary to hack a new route through spiny palms and rattan. After a particularly dense section the Imperial Cave streamway was found.

Imperial Cave takes marginal drainage from both north and south via two entrances. The two streams join within the cave before entering a sump and this water eventually joins the Leopard Cave streamway. During 1988, the Penan had hacked a route up and over the Imperial Cave batu but later in the expedition this was abandoned for a more level but longer route around. On this occasion it was decided to go over the top, as this would be more direct. Although successful, this only added to the dehydration.

Three previous expeditions had slogged over and around this batu because ‘someone’ said there was a sump in Imperial Cave, which prevented an easy route through; in all this time no one thought to check this out! However, the Caves of Mulu ’80 report states “A notable feature of this cave is that the journey between the two entrances is much easier underground than through the forest” Oh bother!

From the far side of the batu, Blackrock’s Centipede entrance is only 200m away. This is where theory and practice began to diverge. What appears as 200m on the survey can seem endless when tired, dehydrated and surrounded by a dense tangle of secondary forest.

More hacking led to a point where a clear slope leads up to small cliffs. Both Richard and I remembered this as ‘the climb up to Blackrock’ – how wrong you can be: it’s amazing how the memory fades over 15 years! Yes, there was a ‘familiar’ slope, yes there was a small cliff, yes there was a cave, but no, it wasn’t Blackrock and no we hadn’t found it 15 years before. Light was beginning to fade, as it does very quickly on this side of the mountain. A scout around the area didn’t reveal anything that remotely resembled the Blackrock entrance so we decided to bivvy the night in the new entrance.

Narrow squeezes led into a rift passage where climbs led up to a 5m tube, heading into the mountain. Other tubes led round to a tall rift that appeared to lead into the same open space as the tube above. After much grovelling around, a narrow but suitable bivvy spot was found and we bedded down for the night. This must be the driest cave in Mulu and by the morning thirst was the main complaint. An early start was made and we headed out – all advice about boiling water was cast to the wind as the first surface stream was consumed without hesitation!

We headed further north in an attempt to find Racer entrance. This had been discovered from the inside and Matt thought that it could be seen from the track – oh, how the memory plays tricks! After more bashing around the group admitted defeat and decided to head back for Camp 5. The Centipede entrance was never found, although Richard did locate another slope up that ‘looked familiar’!

Back at Camp 5, further inspection of the aerial photos appeared to show high ground between the river and the Racer entrance from approximately the 3km point on the main track. If this was so, then there would be a better chance of cutting through to the side of the mountain. Accordingly, Richard and I set off on another marathon. The 3km point is south of the new river crossing and lies on the new island. At this point the track is close to the river bank. Immediately on the other side of the river is a band of karst and a sizeable stream joins the main flow. Crossing the stream led to a large dry cave entrance. A scout around to the left led to a resurgence. As we had only a minimum of light we took note of the entrances and pressed on towards the mountain. As predicted, the going was fairly easy, although this is a relative term in this environment! After an hour we reached the mountain near Racer and joined the route from a few days earlier.

Although it was still a long slog from Camp 5, this new route was a much easier way to access the area. Unfortunately after a great deal of poking around we agreed that Blackrock must have been a figment of our imaginations and called it a day. The failure to find Racer remains something of an embarrassment. It was eventually agreed that the best way to find the Blackrock entrances would be to survey from Imperial Cave’s northern entrance.

Alas, Blackrock remains temporarily lost!

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