Michill Bank Mine - Phil Wolstenholme

Wednesday, 30 July, 2014

Present - Adam Russell (PDMHS), Phil Wolstenholme

This trip was an investigative one, as no-one seems to know anything about this strange hole, despite its location. Situated above the Pindale road halfway up the hillside, the opencut is a triangular entrance at the bottom end of what I believe to be Weather Rake, which traverses obliquely up the hillside and then down the east flank of Cavedale. I briefly visited with Martyn last year, and a quick look down the single pitch showed a possible level at the bottom, so it was added to the list of places to look at. There's not much known on this hill, cave or mine, so all leads must be checked! The entrance showed no signs of ever being visited by cavers before, and the single pitch, about 7m, was too high and wide for free-climbing, so we took a drill and some stainless bolts/hangers. The entrance is a vertical slot in the vein with a stable false floor a couple of metres below the entrance section, which leads to the ledge overlooking the pitch. Stacked deads on the far wall and small openings hinted at backfilled workings above and behind, and some of the roof is slabbed-over. Much loose or fractured rock had to be kicked down before a safe stance was possible for bolting. As daylight penetrates some of the mine, green algae also grows on some of the surfaces.

Once I'd installed a short traverse and a Y-hang, we dropped down into a roughly circular chamber, wider than the vein, and floored with deads. A small level continues SW into the hill and downwards for a few metres following the main vein (at this point very orange massive calcite), but was quickly abandoned, presumably due to poor yields. However, in the back and roof of this small chamber, fallen deads have a definite draught emanating from them, but a dig would require pulling them all down. A short climb up above this level leads into another, blasted level with quite large (1") shotholes. A lower arch then leads into a 'staircase' cut into the vein, rising almost vertically upwards, but easily free-climbed. This vein-shaft leads quickly to another free-climbing section back over the top of the lower section, and upwards further for several metres. At the top of the slope, a window looks back into the main chamber.

Above, a vertical floating packwall of deads rises a few metres further into a vertical section of stope, with further backfill at the top, blocking any way on - this is probably the other side of the top backfilled opening visible from the entrance pitch head. Several cascades of flowstone are present, indicating some age to the workings in places as the shotholes are driven into the flowstone, indicating widening of existing natural passage, but the larger shotholes suggest re-work in the 19th century, though without any Barmaster's records, or name of the mine to check, we're clueless as to its provenance. It's also possible that it's a SW-trending vein off Red Seats Vein, which runs parallel to the lower Pindale road.

Most of the mineralisation present was massive fibrous calcite, with some interesting turquoise deposits of what appears to be malachite - not that common in Castleton. Jim Rieuwerts thinks it may even be aurichalcite or rosasite. It has been found very rarely on Dirtlow Rake, and I found a small amount of possible native copper in the tuff in PIndale End Mine last year, so there's obviously some different mineralisation happening in the reef rocks as you trend east. I've contacted Richard Shaw of the BGS, so if they want a sample we'll inform Natural England and get permission to scrape some off.One interesting aspect was the almost total absence of galena - only one tiny smidge was seen, which is unusual, unless it was all centred in the vein, with no additional, smaller veins. There was some obvious small-scale natural development, it being so closer to surface, with small joints and clay-filled cavities visible. So no new cave, and only a bit of mine to explore, but very interesting all the same, and clean and dry too. And sunshine just outside. What more could you ask for on a summer day?

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30th July 2014

Adam and I returned to the mystery Michilll Bank mine today to collect some mineral samples for further analysis and make a simple survey. Some research by Adam had found that miraculously, our site is not within the Castleton SSSI boundary, nor the Dirtlow/Pindale one either - it sits neatly between them, and so we didn't technically need NE's permission, and we were only taking tiny samples anyway. Firstly, we walked up Cave Dale until the point where the prominent vein (probably Weather Rake) crosses the dale, and then we began carefully zig-zagging up the very steep, wet slope, following the vein to the top, just in case there was anything interesting to find. Apart from a few tiny opencuts and maybe a backfilled shaft, not much to report. On the top of the hill is clearly evidence of early mining, with a patch of closely-spaced hillocks showing a probable pipe-working. No obvious shaft remains, but several piles of deads/wallrock along the top of the hill could be covering shafts, but very hard to tell without moving them all. There is the trace of a vein running roughly E-W for a while, marked by small hillocks, but that's about it.

We then descended the very wet and slippery slope to the mine entrance, and I managed to fix the jammed bolts and re-fix the hangers to rig a rope, whilst Adam made some measurements of the entrance with a Disto. Once down, we took some small pieces of the possible malachite, and I also took a small nodule of probably hematite or limonite with some strange encrustations on it. Whilst Adam surveyed, I busied myself photographing all the bits I missed last time, mostly mineralisation and rock close-ups - which is very crinoidy and eroded, with what seems to be tiny lenses of chert scattered throughout - I'm guessing this is more reef limestone, and as we're only feet underground, probably a bit mashed-up. We found a toad and a small frog mooching about in there, and Adam decided that the toad at least was worth liberating, despite my pointing out (as existential devil's advocate) that it may have spent weeks just getting to that spot for some peace and quiet.

I also found a small piece of galena at last, and a tiny exposure remaining in the vein, so at least we know that is what they were probably looking for, but the odd minerals and the proximity to Dirtlow Rake show that something different is happening to the rock as you go eastwards. Whether there's any cave in the hill remains to be seen, but this entrance at least (probably) doesn't go any further - but has turned out to be far more interesting than I expected.

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30th June 2015

I've improved the rigging for the mine this afternoon, as getting in and out of the 'open-air' section was a bit dodgy. I've added 8mm stainless bolts/hangers on both walls for a Y-hang across the vein at the very beginning, which drops you onto the solid backfilled floor leading to the traverse. This means there's no more air-walking on slippery ledges before you can get to a point of safety. The first hanger of the 2-bolt traverse is loose due to a jammed nut, but the bolt is sound, and is well back from the edge.

I've also bolted another anchor for a deviation on the opposite wall to the main Y-hang into the mine, as there was some nasty rope-rub coming back up, and I've added a maillion and cord to the correct length, so it just needs a snapgate krab for the trip. But for the record, the whole mine can now be easily rigged from the entrance to the floor with a 20m rope, and it's all done in stainless, for posterity. I'll try and get round to drawing up a topo soon.