Post date: Apr 10, 2011 11:42:51 AM

The end in sight...

Cavers: Aileen, Les, Al

After the good progress made last summer in the downstream dig, we were keen to get back so after several weeks of good weather we thought that Black Burn Cave would once again be dry. We hoped that a few hours would get us through, although mindful that the winter floods might have caused further collapse in the cave. We had left the dig with an unstable gravel slope on the left immediately beyond the large boulder at its entrance, so we packed scaffolding and timber shoring to hold this up. A kibble, rope, 8mm handline, shovel, hammer and crowbar completed the load in. Fortunately the lower (furthest down the gorge) entrance was easily passable once the tree trunks Steve and i had placed in it were removed (they had been wedged further in), as this is the easiest and quickest way into the cave. It avoids the small dog-leg tube and awkward first climb from the middle entrance, and the exposed climbs down from the upper entrance. The bags and scaffolding were soon passed down the second climb and we went straight to the dig.

The dam built two years previously was still standing and doing a sterling job of directing the stream towards the dig. Although the dig was dry, there was a large pool immediately before this. While Aileen went back to break the dam and redirect the stream, Les took a first look at the dig. Sure enough further collapses had occurred. The loose gravel left wall had gone, and in its place were two large boulders, which seemed quite stable although their foundations may need a closer look. The draught had also gone, making digging quite unpleasant. Les started on the gravel and small rocks, which i used to fill in the pool. We reached the furthest point from the previous year, and Les went back to get the crowbar from Aileen as the next part required a bit of kerplunk. The annoying white rock in the entrance prevented quick exiting as the boulders fell, so each poke had to be carefully planned with an arm in front of the head for a bit of protection as the boulders rolled down. A bit more worrying was the hanging death being exposed higher in the rift, but very pleasingly the left wall turned out to be solid limestone. Eventually i had had enough, with a pounding headache and struggling to breathe in air that was thick enough to chew, and swapped out with Les for a breather.

Les, and then Aileen, cleared buckets of gravel and cobbles, and also started chipping the white rock down, millimetre by millimetre but gaining useful moving space. The air was still bad, as the digger's body mostly filled the passage and prevented air circulating. When i took a turn again the progress made by Les and Aileen now allowed me to stand in the rift and tackle the blockage from above. After a few kibbles more were removed the draught started coming back and there also seemed to be open passage ahead. I started worming up and forward, tumbling rocks and gravel down and pushing them back with my feet to Les who filled more and more kibbles. As it looked like we were very definitely through in a few more feet of digging i took a good look from the higher position i was in at the upper part of the rift. This was not as frightening as it had been previously, and the winter flooding had stabilised it quite nicely. At the very top of the rift it appeared to go into the brown muck that is prevalent at high levels in the cave, and this is probably the source of the gravel and cobbles. The hanging death was the worst immediate danger, and i took a better look at this. It was possible to remove all the loose rocks from above two well jammed boulders and make it less of a hazard. This done i returned to wormholing forwards. Sadly, although i could soon see into the open continuation and a triangular passage leading off from the left wall of the rift, at the higher level i was at the rift was just too tight to comfortably pass when there was no maneouvering room ahead. With helmet off i got a little further but it just wasn't worth the risk of getting stuck as i breathed out to pass...

The way on was definitely at floor level. Aileen had a go at the squeeze and then started work on clearing out the rest of the rift. We worked at this for a further hour or so before calling time. I think we moved at least a cubic metre of fill in four hours of digging (stacking space was becoming an issue towards the end!), with about 1/3 as much again remaining in the lower (and wider) part of the rift. One or two more hours digging should see the dig finished. It's now possible to bring the kibble up to the dig face, making digging quicker. We didn't place any scaffolding as the dig is stable enough at present, however for a long term flood-resistant solution it may be prudent to stick the scaffolding in the ceiling with boards to hold out the gravel and small rocks.

For a bit of variety, and since we weren't carrying scaffolding, we exited by the original, upper entrance, in my opinion the finest of the three although the climbs are, well, exciting (fun on the way out [up] but probably not so much fun on the way in [down]).

Al

Aileen filling kibbles in Black Burn Cave (photos LB)

Could almost be Papua New Guinea...? Dodgy climb in and out of Black Burn Gorge (photo LB)