Slack Hole
Digging in the next field up from Titan seems like a sensible approach....
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- Written by: Rob Eavis
- Category: Slack Hole
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01/05/2025
Hal, Rob, Jon, Luke, Chris, Bog, Joe
Massive team tonight, mostly because I wasn’t expecting to make it back from Dover on time and just about managed. Me Luke and Hal started on surface whilst the others hit the dig. Firstly they passed up my datalogger which has been measuring the temp and humidity since last week, which I then sat on surface with my laptop and downloaded the data like a proper geek; more on that later.
At the dig they finished off taking the floor a bit lower then installed some minimal scaffolding to protect the way forwards. Once in they started to attack the boulder. We had hoped to have some remote pills for this but nobody brought any so we had to rely on our trusted caps. A brave move considering the positioning; I was happy to not be involved to be honest. However all seemed to go ok, the scaf took some weight and the boulder started to shrink. By the end it is now possible to see passed the boulder and into the rocks ahead, which look quite small and possibly tricky to be honest, but we’ll know more after the next trip.
Before we left I set off a big smoke bomb, even though the draft had almost entirely disappeared, but it kinda felt like I input a little at least.
GEEKY BIT
Draught study
The temp and humidity logger was installed from 24th April to 1st May. During this period the weather was increasingly glorious, especially for Rowter Farm, so I was hoping for some excellent reversing being visible.
Temp and humidity data from Historical Weather API
Hypothesis
When cold (below say 8°C) the chimney effect should blow out the top entrance, sucking air from deep within the hill. This has been seen previously in snow. All of the dig should be a steady 8°C and 100% humidity. Then when hot the warm surface air will be sucked into the cave and off to the significantly lower entrance, through all that juicy cave we’re going to find soon. During this the entrance will be surface temperature and as you go deeper down our dig the temp will reduce (and humidity increase) slightly before it reaches the logger at the dig face.
Results
The logger read a steady 7°C and 100% humidity for the full week! Big surprise.
Additional observations
On this Thursday the surface temp was over 20°C and the top entrance was draughting in strongly, as expected. The dig was draughting away as expected, but still reading 7°C. What’s more, the spoil pipe to surface was draughting out this cold air, and so was the bottom of the shakehole.
By the end of the session the surface temp had dropped rapidly and all these directions indeed reversed, although the draught speed was noticeably less and the pipe was a very changeable.
Interpretation
It’s mad such a strong draught can be created with a maximum of 12m of vertical difference. This circular draught doesn’t look good for cave exploration.
The surface air must cool down to cave temp (and humidity) in the ~40m length of the dig, which to me feels crazy fast. This is the only explanation for the steady readings at the dig face. Presumably the extremely high surface area of boulder chokes helps with this rapid thermal transfer, and the high thermal mass means there is was no measurable increase after 7 days of hot weather.
Schematic showing the two conditions side by side
So the draught could well be very misleading and just lead us to the surface. However it may not be totally useless. There is still (limited) potential for an additional input/exit from below. It would need to be quite a restricted route such that the flow is kept to a minimum, otherwise it would overpower the circular draught we are seeing.
My suggestion now is to sink a small, exploratory shaft in the centre of the shakehole and see what happens. If the bottom of the shaft stops draughting quickly then we can assuming it’s probably not coming from deep below. Doesn’t mean it wouldn’t be worth continuing, only that we could probably ignore the draught at this site.
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- Written by: Rob Eavis
- Category: Slack Hole
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Jon, Hal, Chris, Jim, Joe, Rob
I'd missed the last 3 trips due to holiday, so was biting at the bit to see what the lads had been up to. Also after last week they were a little unsure of the best way on and wanted someone else (me) to make a decision.
Hal and Jim chose to stay topside so us "youngsters" headed down. Me n Chris went straight to the dig whilst Joe helps Jon with some photos further back. It's awesome to get your tackle bag delivered down the pipe right where you need it!
Chris dug for half an hour then i had a go. We were just heading down in the floor to see if it changed and started to open up at all. It didn't, unfortunately, just packed with mud. J&J joined us and we had a 5 minute natter about the best route. I spouted some bullshit which they seemingly needed to hear and we decided to change plan and head horizontally, following the draught. This is clean and draughts pretty well, but looks like it could be quite lose so we'll have to be careful. Weirdly it's kinda back towards the shakehole and the other entrance, which doesn't feel right.
I installed a temperature and humidity datalogger to try decipher what the draught is telling us. Possibly a stupid academic exercise which will end up with us misinterpreting the results and doing the wrong thing anyway, but TBF that does sound like something i'd do.
Joe spent 30 mins attacking the first boulder then Jim made his first input of the night by shouting down the tube "Pub". He was right, the pub was good.
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- Written by: Jon Pemberton
- Category: Slack Hole
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Luke, Jon, Ben, Hal
A special bank holiday Monday treat instigated by lukey boy. We met up at Rowter around 1:30 p.m. and didn't waste much time kitting up and heading over to the shakehole. Luckily for us Ben had kindly offered to be the surface donkey and had the foresight to bring a shelter for the surface. Hal Luke and I made great progress removing a few key placed boulders in the floor. Three people underground works really well down here, although I do feel bad for Benny boy being on his tod (2 on surface is more social). We stayed for a couple of hours before heading to the anchor for refreshments and debrief.
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- Written by: Chris Hibberts
- Category: Slack Hole
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Luke, Chris, Ben, Jim
First actual Awesome digging sesh.
Slack Hole Session 1
After Conversations with the farmer last week about making the entrance safer (especially as the field was starting to fill up with lambs) I managed to acquire a sheet of Walkway grating big enough to cover the entrance hole.
We met at Rowter around 6:15 and after very refreshing pre-beers in the sun, drills, scaff and the grate was divided up between the group. Whilst walking through the gate to the field the Farmer spotted Jim and Myself struggling with the grate and kindly offered for his daughter to run it over to the shake hole on the back of her Quadbike.
Arriving at the shake hole Jim and I head to the dig face with Luke and Ben staying on the surface to haul out spoil and tidy the entrance ready for the grate.
We made steady progress removing a mix of rocks and mud from the floor trying to uncover some of the obviously larger boulders. Several of the larger rocks were capped to make them a suitable size to fit up the Tube. It really is a sociable dig having the voice connection to surface.
After about 40 mins of digging Jim took over at the front and more of the small rock and spoil were removed for about another 40 mins by which time thirst was starting to set in and the call for the Pub was heard. No scaffolding was needed to support the rocks we were undermining on this trip, but with a few bigger boulders, holding up the ones above, it was going to be a must for the next trip.
Rob had tasked us with trying to understand what the draft was doing at the dig face by placing a Temperature and Humidity logger to collect data over the next two weeks. He'd had sent me instructions which I had instantly forgotten and the long press on the start button didn’t seem to have the desired result, after cycling through the various screens and more long presses I was sure it wasn’t working but decided to leave it anyway and see what happens.
It takes around 3-4 mins to get from the dig face to the entrance and even after 2 trips it was starting to feel familiar. At the surface we were greeted by Ben and Luke and the new grate was installed over the top.
We quickly head back the cars for a swift change and off to the Pub to de-brief and decide what next weeks plan of attack was. Checking Rob’s logger instructions, it was now evident that I’d left if in a pointless state.
Ben Loves Selfies.... At the hauling pipe - Photo by Ben Marks
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- Written by: Rob Eavis
- Category: Slack Hole
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Luke, Chris, Moose, Rob
With LWS now firmly out of the way, we needed a new project. There's lots to do deep beyond Cussey, but the Team needed something else as well, ideally a nice summer surface project. After much debating and disagreeing, plus a few exploratory trips to some shitty projects, we pulled on a few coat tails and got ourselves a look in at Slack Hole. It was originally dug by PB Smith in the 70s, well actually a smaller shakehole just to the east, and then more recently by Moose around 2009 - 2011. Since then it has laid abandoned, awaiting a team.
It is one of the largest shake holes in the Peak and situated right at the top of Cavedale. This is the next field on from Titan, which gives a hint it's in a good location. The closest cave is the Flatmate at the end of the Far Sump Extensions, which is approx 180m below! And it draughts, strongly! Prospects don't get much better than this. Myself and Moose have massively overthought the potential formation of it and what lies below, so if nothing else we need proving wrong....
After a good introduction with the Rowter farmers given by Moose, we grabbed our beers and headed over. The shake hole is indeed massive. Moose's dig started on the southern edge and now worms a route down and anticlockwise around to the east of the centre. The entrance was loose and in desperate need of a gate to stop lambs falling in, an easy win with relationships which we'll sort next trip. A short diversion to the right drops into a natural pot but this doesn't have much draught so is likely to be left alone, at least for now. Following the only other route reaches the dig face after about 50m.
Slightly before the end a spurious pipe descends from the left, roughly 300mm in diameter. This is a classic Moosism. Moving spoil from the end was getting a bit tricky. So they surveyed the dig and realised this point was only 4m from the surface. Rather than putting a new entrance, they sank this pipe through and made up a bespoke bucket to fit. On the surface this pipe is hidden by a hilarious hinged rock!
Whilst Moose hung out on the surface, we set about poking everything we could. The place is weirdly clean washed, almost like no glacial fill dared to enter. The boulders are fluted and water worn, and many have stal formations on them; a weird mix of old and new. The problem Moose encountered before is that basically everywhere draughts! This is still true, so deciding which is the best way is made more tricky. After a little discussions we decided on a spot just back from the face which had been backfilled a bit but looked the most appetising, and cunningly positioned reyt close to the hauling pipe. The draught is certainly very strong there and the way on down looks pretty easy digging.
Today was just for a look so we headed out to the pub. Everyone seems very keen to give it go this summer, lets see if we find some answers...
