Mulu Caves ‘09

2007 had seen major extensions in Whiterock with large trunk passages heading both north and south. Although the cave had several connections to Blackrock, and thereby the Clearwater System, it still seemed to have a life of its own. Large open leads had been left by the departing explorers, which the 2009 expedition returned to with relish. An important scientific project was also begun.

Lower Borderline, Whiterock Cave - photo © Robbie Shone

This expedition had been planned as a two month expedition with two separate teams for a month each. The first and smaller team of eight cavers immediately examined the open leads in Whiterock, and were not disappointed. Borderline headed north from a junction in Bigness South and its 4.5km of passageway quickly revealed itself as part of Whiterock’s major north-south conduit, linking with 1954 to provide a high level backbone all the way from the Melinau Gorge to Api Chamber. For most of its 8km distance this ‘backbone’ measures 25m x 25m in cross section. A corresponding large passage also headed south from Borderline as the Big Issue, another 2km of large cave rejoining the Bigness South passage just before Api Chamber.

With many other smaller yet significant finds, including loops and shortcuts across the beds, the first team surveyed 14km of cave within a couple of weeks, despite unseasonally high rainfall making forest travel somewhat difficult. But despite these big gains, some passages obstinately refused to ‘go’. The major high level trunk passage of Api Birthday South could not be forced further despite several attempts. And the search for a way beyond Api Chamber also proved futile. Most frustrating of all, the strongly draughting ramp near Poppets Passage, which promised to lead to a higher level of the cave, choked solidly at its high point, with the strong draught pouring down through small gaps in the calcified boulders.

With local help the first team also pioneered a route around the crest of the Benarat cliffs and made an exposed abseil high above the forest floor into Hole of the Moon, the large square entrance which had tantalised all who stayed at Camp 5 and had been the target of a climbing attempt in 2005. The cave was large and struck off into the hillside for several kilometres.

The Mother of All Voids, Hurricane Hole - photo © Robbie Shone

The first team flew home well satisfied, having nabbed the major leads! What would be left for team two?

Indeed it was harder work. But whittling away at the smaller side leads still provided some 4+km of passage in the mid and southern sectors of Whiterock, including the unfinished Thirsty Ferret and the large but short lived passage of Paint It Black. Meanwhile a party exploring the slopes of northern Api rediscovered Parang Cave (1994) and pushed it through five tight squeezes and small passage to within 50m of Whiterock’s northern terminus. But the ‘northern entrance’ was not to be. The same team then decided to look for a way out rather than a way in, but despite surveying a further kilometre at the northern end of 1954, the sought for exit remained elusive. Whilst returning from this effort, a smaller side lead was examined and noticed to take a draught.

With Whiterock appearing to be drying up, a further trip to Hole of the Moon was made, linking it with Tiger Cave and topping off the survey with further scientific sampling. After many years in the wilderness, Blackrock’s entrance was at last relocated and a team camped at Milliways and examined a lead in Pete’s Pecadillo which it was hoped would lead to larger upper levels. But both routes were choked. Forays were also made onto the western slopes of Benarat to try and locate the window entrances of Cobweb’s Just A Mile passage. This too was unsuccessful.

The Whiterock River - photo © Robbie Shone

With objectives petering out, a team returned to polish off some small leads in Whiterock. The draughting side lead off 1954 was followed down a steep ramp, completely missing the Northern Line, into a complex of tubes some 130m below the 1954 level. Here the key turned and beyond several low crawls a final ramp down burst spectacularly into the roof of the Whiterock River. The upstream feeder of the Clearwater River had been found and provided 4km of romping river cave, which had to be left wide open both north and south as time ran out on the expedition.

Over 27km of cave was explored and surveyed on the expedition, 23.4km of it in Whiterock Cave. An important scientific programme in cosmogenic dating of cave sediments was also begun, and the discovery of the Whiterock River offers many possibilities for the next expedition. Whiterock continues to astound!

For further information log on website :
http://www.mulucaves.org/wordpress/expeditions/mulu-caves-09