More cave for Jenga Pot


Following the discovery of some lengthy extensions for Jenga Pot, we never managed to get it all surveyed before the winter weather refilled the sumps and prevented entry again. We've now finally had a chance to get through the sumps and into the new areas discovered in 2020.

The Covid Extensions, despite being pretty grim in places actually yield some excellent bits of passage. Some of it is even walking height! :LOL:

By the end of last year we'd managed to get the Covid Extensions surveyed but the exact direction and location on the surface of an exciting side passage remained a frustrating mystery. The Second Wave has now been mostly surveyed yielding another 150+ meters of passage for the system.

Divers are scheduled for the several sumps soon so more updates will follow!


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The following was my trip report if anyone is interested (probably a little too detailed for anyone without intricate knowledge of the system, but posting for the benefit of a small handful who might be interested):

On 26th June, only 22 months since the passage was first discovered, myself and Gary decided to finally survey The Second Wave. This is the passage that goes off on the right shortly before Tree Root Chamber in the 2020 Covid Extensions of Jenga Pot. We surveyed most of the Covid Extensions in 2020, and then to Tree Root Chamber in April 2021, however, on that latter trip, we had a quick look up The Second Wave, and found the 10m long low airspace duck to be too full. It seems a couple of months are needed after each flood for this to drain enough. After that, all our pumping equipment failed, meaning summer 2021 was a lengthy re-cabling and re-wiring job.

We never regained entry to the Covid Extensions after April 2021, so The Second Wave, an enticing northbound passage which reaches what we assumed to be the Excalibur Pot streamway (200m downstream of where it is lost in Excalibur Pot) remained unsurveyed.

We were not specifically looking forward to this; I remember what an ordeal a trip to the furthest reaches of Jenga Pot is, and doing so while surveying was going to be especially demanding.

We set off down about 3:30pm after fueling the generator, however our efforts were nearly thwarted at Sump Three. On Wednesday just gone, Gary had drilled the fissure above the sump, the start of his efforts to bypass Sump Three. This meant unplugging the pump to plug in the drill. Therefore, on arrival at the sump today we plugged in the pump, and powered on... but nothing.

Some jiggling of the pump and connector later, we established that power was arriving perfectly well at the extension, but the pump wasn't firing. We were about to give up when Gary gave the contacts a final scrub, and as if by magic, the pump fired up on a last attempt. Only 20 minutes later, the water was lowered several inches and we were through.

We made quick progress down Pandemic Passage, and downstream to the major junction where the right passage leads off towards Tree Root Chamber and The Second Wave. This junction, and the right passage has never really been named. In keeping with the Covid theme, we called it Whitty Junction, and the right passage to Tree Root Chamber, we called Next Slide Please... which seemed appropriate given that it is relentless sliding over slippery mud.

We arrived at the small aven where surveying to Tree Root Chamber commenced last April, and onto the small pool where The Second Wave commences on the right (Tree Root Chamber is straight on here). I was pleased to see that a single survey leg would clear the several metres of slop and into the dry passage beyond.

We surveyed on, in the rather excellent passage, reaching 3m wide and 1m tall, with large, deep scallops filled with stream pebbles. This really is a magnificent passage which once carried a lot of water, and perhaps still does in flood. If anyone is ever down here to find out what happens in flood, they are probably in for a very bad day.

Sadly this passage soon ended and we were faced with the 10m long, low airspace duck. Neoprene hoods had been brought for this purpose and, I was once again delighted to see that a single survey shot would clear the water to a station on the sandbank opposite. The duck itself was proper submersion, head sideways, spluttery, taking a slalom route between chert nodules on the roof. The water was higher then when we first found it in August 2020, but lower than when we last visited in April 2021 (when it had barely an inch of airspace). It seems that this duck really does need at least a few months of the cave not flooding to become low enough to pass.

What little warmth we had left was quickly lost into the water of the duck, and surveying resumed as quickly as possible to avoid time to ponder the squalor we had just faced; and that awaited us on the way back.

Onwards, the passage is a crawl on fine gravel with mud banking on both sides, steadily enlarging, even to walking height for 15m or so, before reaching, a narrowing lined with bulbous cherty projections. Just at the start of this is the high draughting aven we are so curious about. When we were last here (Aug 2020) there was a howling (I really mean that... you could hear it) draught coming down, cold, fresh and very strong. Efforts to scale it were unsuccessful as it was so slippery. Today though, there was no draught whatsoever.

We hypothesise that this aven could go up towards a dig we have in the side of the River Dove, in the next valley west; interestingly, this dig was open down to a narrow, clean-washed fissure at -3m in August 2020; But has since completely filled in (the winter floods fill it with soil and leaves). Therefore, the draught may have been originating from that dig.

Down into the 'Excalibur' streamway (or what we think is the Excalibur streamway) the chills were starting to set in, and we felt a very long way from home. Nonetheless, we were determined to finish, so we set off surveying downstream where our 2020 explorations had pushed for about 60m to a terminal sump. Around the corner, we were greeted with the first lower section where chert nodules forced a thrash in the water back in 2020; Today however this would have required a back-crawl with full submersion. The water was certainly a little higher today, and presumably optimum time to explore the downstream passage is late summer when the water is at its lowest... and when you aren't already freezing!

We were not in the mood for another low airspace swim; Surveying of the 50m or so passage downstream of here will need to wait, but we did take a shot to at least fix the bearing, and my recollection is that the passage from that point is more or less a straight line.

Upstream, we took a shot to the first duck, which in 2020 was 4-5 inches airspace, but today was only 2-3 inches; Again, being already chilly and tired we declined to survey through this, thus leaving 15m of cave leading to the upstream sump unsurveyed, but the direction roughly known.

The next trip here may well be with divers, as the upstream and downstream sumps are spacious and offer a lot of promise.

The long slog out commenced; it really is quite an ordeal, taking an hour to exit Jenga from the furthest point, now several kg heavier with water and mud filling every orifice of our kit. The pumps were off when we arrived back at the sumps, so the genny must have run out of fuel, but the sumps have been dry for long enough now that they take days or even weeks to refill, so we were never in any danger.

We arrived out at 8pm, surprised and pleased to find two cans of Sprite and two bags of crisps waiting for us at the entrance, and then John Dale at his car. Thanks for popping down to check on us John!

Curry at Easingwold on way home to York was a worthy reward.


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Jenga Survey.jpg

The survex line data of the entire system following last Saturday's surveying session, completing 'The Second Wave'. Arrows show water flow.

The classic 'Excalibur Pot' trip is from the top entrance to the Main Streamway. The entrance right-middle is Jenga Pot. Clearly there is a 'Grand Circle' waiting to be completed... but we need to wait until a diver has tackled Sump 6 to see whether this is ever likely to be feasible. For now, a connection to the River Dove valley (west side) is the most exciting prospect, and the possibility of more passages at higher level there.

That's more or less the entire known system surveyed apart from a few short sections estimated in red... or at least it was until today...

Just today, a diver has tackled Sump 4; The upstream percolation streamway (bottom right of survey). He reports passing a 20m sump, into large passage with a big chamber, another large passage and another sump. He was sufficiently excited that we are returning tomorrow so he can explore!!!

And that's just the first (and we thought, least promising) of the four sumps in the Jenga Covid Extensions.

The North York Moors saga continues...


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It’s been a few months since we provided any update on the goings on in the North York Moors.

Work in the 2020 ‘Covid Extensions’ in Jenga Pot has been continuing in parallel with another high-prospect project elsewhere (about 4-5 miles east).

This summer we have finished surveying of the remaining major sections of the cave and are close to being able to publish an updated version of the survey.

The Covid Extensions contains four sumps: Upstream and Downstream (sumps 4 and 5) in the small, presumed percolation-fed stream in Pandemic Passage, and then Upstream and Downstream (sumps 6 and 7) in the Excalibur Pot streamway (rediscovered about 300m downstream of the furthest limit of exploration in Excalibur Pot) as shown in the survey above.

Sump 4 has been the greatest focus of attention this year. This is the upstream of the first streamway encountered in the Covid Extensions. We initially thought this must be the lost ‘Shit Creek’ streamway from Excalibur Pot, but some quick compass measurements revealed the water to be coming from the south, not the north, so this theory quickly collapsed.

The stream emerges from a low arch, a canal, which you can enjoyably float through for several metres until a low airspace duck is reached. When we first found this there was barely 2-3 inches of airspace for about 6ft, but some dredging of the downstream floor has managed to achieve 5 inches of airspace, which is decent. Beyond here, the passage becomes low crawling in a gravel stream with a few short walking-height sections, for about 40m, until the true Sump 4 is reached.

Ian ‘Snazzy’ Dawson dived Sump 4 back in 2020, continuing south, surfacing after about 15-20m in a low-headspace continuation of the stream passage; but with this being one of his first solo cave dives, and the water being freezing, he didn’t hang around to explore.

Returning to Sump 4 this year we have found the entrance to it to be badly silted up, prohibiting access to Chris Armstrong who attempted to dive (Snazzy has moved to Australia so didn’t fancy coming out on Wednesday night to have another go).

However, above Sump 4 on the left is a high-level passage which starts spacious, but after 15m became progressively too restricted due to thick, sticky mud. Over the last few months, we have made several visits here trying to dig a way on, as black space was always visible ahead, and we could hear the enticing drip-drip of water and a decent echo. We assumed this might provide a bypass to Sump 4 and back to the streamway that Snazzy glimpsed a few years earlier.

The breakthrough came a few weeks ago, dropping down over the mud into a low section of new streamway. Downstream, the water vanishes through chert blockages into what feels like a pool, but there is no way this could be where Snazzy surfaced, as it is totally blocked with chert. We reckon Snazzy must have surfaced in a short section of ‘dry’ passage, which only 5-6m further on sumped again, just downstream of where we have now intercepted.

Upstream in the new section, 20m of low thrashing in the water and another sump was reached; This was pushed by Andrew ‘ChooChoo’ Northall and Richard ‘Sparky’ Edwards as best as possible without diving equipment, but without success.

Sparky and Andrew managed to capture some awesome, video footage; This shows the initial breakthrough, exploration upstream, Andrew pushing the sump, and a short interview with Sparky afterwards, extoling the virtues of the new section of cave. The quality is rough (no high-definition video here), but Gary Douthwaite has edited it together, so you can see that F’ing Hopeless Pot is nowhere near as lovely 🤪

(Ps; lots of bad language, not for those easily offended... subtitles available for those who don't speak Yorkshire).

Thanks to Andrew and Sparky for capturing this!

It is becoming clear that this passage is a continuous alternation between streamway with some airspace, and streamway with none, as the roof rises and dips. Quite how far it goes, we don’t know (not much further we expect), and where it is coming from is an even bigger mystery.

Either way, this is becoming quite a serious Wednesday night project. Last week, work was undertaken to remove a lip of rock and chert which was artificially raising the water level in the new upstream sump, and diving kit is now in place for an attempted push here maybe this week.

As you can see from the video, this is a challenging spot for a diver, but Chris Armstrong seems unusually invested in this hideous opportunity!

We haven’t even attempted the far more promising Sumps 5, 6 and 7, which are spacious and cleaner. For some reason we started with the shittiest sump first. Sumps 5 and 7 offer the prospect of diving downstream and encountering the fabled confluence between the River Dove and Hutton Beck water, where the diver can then swim upstream, exiting at The Well, become the first person to complete the valley to valley through-trip, and be treated as caving royalty for evermore.

While all of this has been going on, myself and Gary have been engineering a route over Sump Three. To get into the Jenga Covid Extensions after a flood we need to pump Sumps 1, 2 and 3. Sump 3 is the only one that had a (tiny) natural fissure over the top. Last Wednesday, we finished the job and engineered a human-sized route through over the top of the sump.

This means that there are now only two sumps to pump out. This is important, because we can simultaneously commence pumping of Sumps 1 and 2 without even going underground; We just fill the generator on the surface, crank it up and go to the pub; However, to pump Sump 3 requires a trip underground to a switchbox after Sump 2. Access will now be much easier.

Lots of exciting stuff going on!
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While Gary was in the mood for editing together video snippets, he has put together the following short video capturing 'Breakthrough day' from summer 2020, when we first broke through Sump Three and into the 1km 'Covid Extensions' in Jenga Pot.

I had forgotten about those mini-interviews! The excitement is somewhat evident :)


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Nearly three years on from the big breakthroughs beyond the sumps in Jenga Pot, we are pleased to publish the latest version of the Jenga Pot/Excalibur Pot survey, including the Covid Extensions. This is fully up to date with the Sump 4 extensions last summer.

This is the culmination of a lot of hard work and some seriously gritty surveying sessions by numerous members of York Caving Club and the North York Moors Caving Club.

As always, the survey is free to download from our website publications page:

We have turned the survey sideways compared to previous versions as this worked better for the paper version. This is a whopping 2025 x 841 mm and is also available to purchase via the above link, priced at £10 plus £3 postage folded or £6 postage rolled in cardboard tube.

Warning: We will be doing our best to make this survey obsolete over the coming few years :dig:


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Psychocrawler, sorry to hear the card payment function isn't working (this is powered through Paypal so somewhat out of our control). I suggest paying via Paypal direct rather than using the card function, or if this isn't suitable, PM me with delivery address and I can give you bank details for a bank transfer payment :)
Psychocrawler, sorry to hear the card payment function isn't working (this is powered through Paypal so somewhat out of our control). I suggest paying via Paypal direct rather than using the card function, or if this isn't suitable, PM me with delivery address and I can give you bank details for a bank transfer payment :)
I see - I didn’t realise that the card payment option was via PayPal. I’ll try again at some point.


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It’s been a challenging year for digging in the North York Moors so far, but lots happening.

Attendance at our Wednesday digging session has remained at record highs, often with 8-12 people turning out each week from York Caving Club and the North York Moors Caving Club. Since May, efforts have been split across two separate projects, with the teams reuniting at The Crown in Hutton-le-Hole afterwards for sandwiches, chips, and beer.

One team (including myself) has been focused on Jenga Pot, where we had arranged two dates for cave divers to come and have a go at Sumps 4c and 5, which offer great potential. To gain access to these sumps, which are in the 2020 Covid Extensions, we need to pump out Sumps 1 and 2 (Sump 3 no longer needs pumping thanks to an overhead bypass we dug last year).

Work here didn’t start until April once we felt confident the surface river had flooded for the last time until the end of summer (the sumps refill instantly if the river floods).

In theory, pumping these sumps should be as simple as firing up a generator on the surface, and both underground pumps should jump into action. About three tanks full of petrol would see these sumps emptied, without us even having to go underground! Or so we hoped…

Things did not go totally to plan. The generator circuit breakers tripped when both pumps were run simultaneously, despite no problems over the last two years. We concluded that either the pumps were drawing more current than they should be, the generator was not delivering the current it once did, or the circuit breaker was tripping too readily. We made progress pumping one sump at a time, but this was painfully slow, and progress was reset when an unexpected mid-May flood of the river refilled the sumps, sending us back to square one again.

The first date for the divers had been arranged for 3rd June, so the race was on to get the sumps pumped again to enable easy access. We even brought a second generator to run both pumps at once, and we finally seemed to be making progress.

We arrived on Wednesday 1st June, expecting both sumps to be empty. We headed underground to check the state of play, only to find Sump 1 still half full, still sumped at the far end, and no noise coming from the pump and no pressure in the pipe. The diving was off!

We turned up the following week with a new pump for Sump 1 (it has been in there since 2014, so we assumed it had finally failed) only to then identify the issue as a loose connection on the surface. A quick fix, so we refocused our efforts on the second diving date of 1st July.

Sumps 1 and 2 were quickly emptied. By now, our usual generator seemed to be running both pumps at once, so the earlier issue, whatever it was, seemed to have magically sorted itself out. Things were finally looking positive and getting divers to sumps 4-5 on 1st July seemed an inevitability.

We even set to work improving the system, replacing connectors, drilling small hooks throughout the cave to support the cables and stop them getting crawled on, and building a double-ammeter to allow a diagnostic readout on the surface of the current being drawn by each pump.

On 28th June we took a trip underground to confirm everything was in place, finding sumps 1 and 2 still empty from the week before. We made quick progress down to sumps 4 and 5. To our surprise, and despite the very dry conditions, the percolation stream flowing out from sump 4 and down to sump 5, was going like a train. The dug squeeze bypassing sump 4 to reach sump 4c, one of the dive targets, was full of water and would need extensive bailing, and the small stream-level squeeze to reach sump 5, which has been easily passable for the last three years, was mostly sumped! This is, by far, the wettest we have seen this streamway, and it took us rather by surprise.

Unfortunately, this meant cancellation of the diving once again, and probably the end of all efforts for this year because we are only a few months away from the end of the dry season.

We will need to dig a channel to prevent the crawl to Sump 4c from filling up like a U-bend, and we will need to mine over the top of the squeeze to sump 5 to enable more guaranteed access, given the rather unpredictable nature of the streamway here. At best we are looking at 2024 for the next diving efforts here now, which is a real disappointment.


Efforts last year to dive Sump 4 (subsequenty bypassed by overhead dig to reach sumps 4b/4c)

As for sumps 6-7, they are much further into the cave, beyond a low-airspace duck, which we know doesn’t drain sufficiently until late summer. They are great targets, being spacious, clean flowing sumps with enormous potential including a likely valley-to-valley connection. However, it will be a long, hard carry for gear and I think the recent challenges just getting divers to sumps 4c/5 (which were supposed to be the easy ones) has given us a reality check. The people-power needed and the high physical challenges associated to reaching and diving these further sumps might be insurmountable. We are going to focus instead on a dig in the next valley which might enable a new surface entrance.

Elsewhere, at our other dig near the hamlet of Cawthorn, 6.5km east of Jenga Pot, things are progressing very nicely. This is already the second active cave system in the North York Moors, and throughout winter takes quite a decent stream, flowing along a boulder filled passage. With summer here, and this stream not flowing, this provides a good chance to make more pleasant progress.

We posted an earlier update on this project here:

This year started with the cave about 65m long and follows a large (2m+ wide, 1m+ high) water-formed passage. These proportions are only evident in a few places, because for the most part, it is just a continuous boulder ruckle. Progress is being achieved through mining, following the route of water, with an encouraging and reliable draught. Every few weeks, efforts are rewarded with a few metres of open progress to yet more boulders with tantalising space beyond. The passage shows no signs of ending... but neither do the boulders!

Currently, the Cawthorn team are arriving at the pub optimistic about progress, and there is a feeling that the dig could ‘go’ at any time. This is particularly true if we can get deeper into the hillside and into better quality limestone where the roof has been less prone to collapse.

The vertical range to the suspected resurgences is over 100m, and the horizontal range is 3-4km. The passage takes a generous stream in wet weather, and the draught is reliable. Hope remains high that this could be the start of the next big North York Moors thing, although nobody is keen to wager on whether it will be next week or next decade that the breakthrough will happen.

Whatever happens, the North York Moors continues to carve a small, but proud place on the speleological map of the United Kingdom, and more discoveries seem inevitable.