Author Topic: One month and one kilometre in the North York Moors  (Read 3722 times)

Offline Cavematt

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Re: One month and one kilometre in the North York Moors
« Reply #25 on: October 09, 2020, 09:59:37 am »
Hi Tamarmole. Guinevere's Slit Sink is roughly around the lowest of the four arrows pointing to the other sinks in the River Dove. It is in the riverbed and has been dived for about 50m downstream towards The Well, reaching a choked area about 50-60m upstream of The Well (no way on located as its just very loose slabs). We assume that The Well is simply the downstream continuation of the same passage.

The Well is just off the bottom of the image under where it says 'To Bogg Hall???'. The Well drops into totally sumped, reasonably spacious passage and has been dived for about 80m downstream I think, also ending at an area of collapse, but with extremely high flow rate rushing through the boulders. The passage heads back under the river and the western hillside rather than straight for Bogg Hall so presumably it turns south somewhere soon after.

Therefore, none of the new passages in Jenga come too close to Guinevere's Slit or The Well and their associated passages. We assume the merger with the Excalibur/Jenga water lies further downstream closer to Bogg Hall.
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Offline Goydenman

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Re: One month and one kilometre in the North York Moors
« Reply #26 on: October 09, 2020, 11:03:34 am »
wow fantastic achievement well done team...turning into such a key system

Offline Cavematt

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Re: One month and one kilometre in the North York Moors
« Reply #27 on: October 09, 2020, 06:34:22 pm »
If anyone is wondering what caving in the North York Moors is really like, these three videos (all a few years old now) sum it up well...

Excalibur Pot walkthrough (the classic sporting route)
(This was mainly made for a presentation at the local village hall so apologies if it seems a bit dumbed down to a caving audience)



A trip through Bogg Hall (the resurgence for all the caves discussed in this thread):
(A superb effort by Ali Rollinson and Ade Turner utilising the 'light raft' which worked remarkably well. The final chamber is The Font, which is 18-20m deep and all the water from Excalibur Pot, Jenga Pot and the River Dove comes up from the bottom of it. Bogg Hall is a magnificent short trip).



What it's like digging in the North York Moors:
A perfect depiction of the efforts that have led us to where we are now!


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Online tamarmole

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Re: One month and one kilometre in the North York Moors
« Reply #28 on: October 09, 2020, 10:01:47 pm »
Hi Tamarmole. Guinevere's Slit Sink is roughly around the lowest of the four arrows pointing to the other sinks in the River Dove. It is in the riverbed and has been dived for about 50m downstream towards The Well, reaching a choked area about 50-60m upstream of The Well (no way on located as its just very loose slabs). We assume that The Well is simply the downstream continuation of the same passage.

The Well is just off the bottom of the image under where it says 'To Bogg Hall???'. The Well drops into totally sumped, reasonably spacious passage and has been dived for about 80m downstream I think, also ending at an area of collapse, but with extremely high flow rate rushing through the boulders. The passage heads back under the river and the western hillside rather than straight for Bogg Hall so presumably it turns south somewhere soon after.

Therefore, none of the new passages in Jenga come too close to Guinevere's Slit or The Well and their associated passages. We assume the merger with the Excalibur/Jenga water lies further downstream closer to Bogg Hall.

Thanks for the clarification.  This is the system we dreamed of in the 90s when we were grovelling around in Dowson's and Lingmoor.  Awesome work indeed.

Offline RobinGriffiths

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Re: One month and one kilometre in the North York Moors
« Reply #29 on: October 09, 2020, 11:25:20 pm »
So these are actually phreatic systems and not tectonic caves like the windypits? Are there other places in the NYM where such systems might develop?

Online tamarmole

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Re: One month and one kilometre in the North York Moors
« Reply #30 on: October 10, 2020, 09:02:32 am »
So these are actually phreatic systems and not tectonic caves like the windypits? Are there other places in the NYM where such systems might develop?

Whilst the North York Moors are probably best known for the windypits (slip rift features) the Hutton Beck/River Dove System is a bona fide water formed cave.  There are fossil fragments of water formed cave across the southern part of the Moors notably Kirkdale cave and the Kirbymoorside caves.  There is also some interesting (unentered) subterranean water flow such as the rising at Howkeld (again near Kirbymoorside).

The great thing about the North York Moors as a caving region is that it is far from played out.

Offline Cavematt

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Re: One month and one kilometre in the North York Moors
« Reply #31 on: October 10, 2020, 11:49:02 am »
Tamarmole is absolutely spot on (Tamarmole; who are you... feel free to PM me).

The Jusassic limestone of the North York Moors spans from Sutton Bank more or less all the way to Scarborough, a 30 mile stretch, covering the bottom few miles of the National Park. There are abandoned phreatic relics all across the area, but most are fully choked with mud. At Kirkdale, there is a 300m abandoned phreatic system called Kirkdale Cave perched several metres above the present day course of Hodge Beck. This will be in the same bed of limestone as Manor Vale Caves in Kirkbymoorside, and no doubt these systems are far more extensive than their current mud/block-choked limits suggest. Phreatic caves will have played a much greater role in the hydrology of the area following previous ice ages. Phreatic relics can be found everywhere, but very few can be extensively explored today.

You are right that some of the major caves are slip-rifts (Windypits). Most of these are between Sutton Bank and Helmsley, with the most substantial ones being part of Duncombe Park Estate (and sadly off-limits to cavers due to no public access to the Estate and the sites being archaeologically sensitive).

Several rivers sink as they cross the limestone; The Rye, Riccal, Hodge Beck, Dove, Hutton Beck, Seven, Derwent etc, with resurgences typically around the A170 road. There may well be systems to find underneath all of these although whether they are totally sumped shallow systems such as the main underground flow of the River Dove, we don't know. There is a huge resurgence pond just next to the road to the west of Pickering (Keld Head) which must have an active system of reasonably proportions feeding it somewhere. We had a project at Gundale, one of the suspected feeding streams, a few years ago but without success.

Undoubtably there is a lot more to find in the area and we've already got our eyes on a few projects outside of the Jenga-Excalibur area, but it isn't easy and the area lacks all the tell-tale signs of other caving regions, and lacks the ease of access of the Yorkshire Dales. We know of one major flood-responsive sink quite high up on the limestone a few miles east of the Jenga-Excalibur system. This has all the hallmarks of a sink into a cave system, although we are struggling to get the necessary permissions to dig there at the moment, but we are still working on that. It's enough to keep us busy for many years to come.
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