Langcliffe Pot
{{Short description|Cave system in North Yorkshire}}
{{Use British English|date=July 2019}}
{{Use dmy dates|date=July 2019}}
{{Infobox cave
| name = Langcliffe Pot
| photo = Entrance to Oddmire Pot, Yorkshire.jpg
| photo_width = 256px
| photo_caption = Oddmire Pot entrance shakehole
| map = North Yorkshire
| map_width= 256px
| map_caption =Showing location of Langcliffe Pot in North Yorkshire
| map_alt =
| location = Great Whernside, North Yorkshire, UK
| coords = {{coord|54.135501|N|2.007961|W|format=dms|display=inline,title}}
| grid_ref_UK = SD 9958 7107
| elevation = {{convert|488|m}}
| geology = Yoredales Limestone
| entrance_count = 2
| hazards = water, loose boulders
| survey = [http://cavemaps.org/surveys/ulsa/full/ULSA%20XXXX%20Langcliffe%20Pot.png ULSA survey on Cavemaps]
| survey_format =
}}
Langcliffe Pot is a cave system on the slopes of Great Whernside in Upper Wharfedale, about {{convert|3|km}} SSE of Kettlewell in North Yorkshire. It is part of the Black Keld Site of Special Scientific Interest where the "underground drainage system which feeds the stream resurgence at Black Keld is one of the largest and deepest in Britain, although only a small proportion of its cave passages are accessible at present."{{cite web|title=Black Keld Catchment SSSI|url=https://necmsi.esdm.co.uk/PDFsForWeb/Citation/2000376.pdf|publisher=Natural England|accessdate=6 April 2017}} Mossdale Caverns is also part of the Black Keld SSSI. Although a considerable length of passage has been explored in Langcliffe Pot, the current end is over {{convert|170|m}} above the resurgence, and over {{convert|4|km|}} in distance. A trip to the far end has been described as "one of the most serious undertakings in British caving".
Description
The entrance lies within a shakehole where a small hole between blocks leads to a ledge at the top of a {{convert|26|m|adj=on}} shaft. This lands in a chamber with a narrow rift passage leading off which degenerates into the Craven Crawl, {{convert|200|m|}} of low, wet passage. At a junction with an inlet, the passage enlarges into Stagger Passage, {{convert|600|m}} of walking and stooping. At the start of a deep canal it passes a passage on the left which is the main way to the alternative entrance of Oddmire Pot. The canal passage continues to meet a major junction at Hammerdale Dub, where over a {{convert|1000|m}} of upstream passages also lead back towards Oddmire Pot. Downstream, {{convert|1500|m}} of boulder-strewn streamway finishes where the water disappears under a wall, but a small passage leads into Boireau Falls Chamber, at the base of which it is possible to regain the stream. This finishes at Nemesis, a {{convert|20|m}} shaft below which a route through a tight and complex boulder choke leads into Gasson's Series. This is initially a high streamway which degenerates into a low wet section, beyond which the passage continues for {{convert|100|m}} before arriving at Poseidon Sump, which has been dived for some {{convert|20|m}} to where it became small. Back at the low pool, a dry inlet passage of fine rift passage and chambers continues for over {{convert|1100|m}} before decreasing in size, and dropping into the large New Fearnought Streamway. Downstream leads to Dementor Sump, which has been dived for {{convert|20|m}} to a blockage. Upstream terminates in a boulder blockage after {{convert|230|m}}.{{cite book|last1=Hill |first1=Elaine|last2=Hall |first2=Adrian |title=Northern Sump Index 2015 |date=2015 |publisher=Cave Diving Group |isbn=978-0-901031-08-2 |pages=17–21}}{{cite journal|last1=Monico|first1=Paul|title=Langcliffe Pot|journal=ULSA Explorations Journal II|date=1989|pages=31–41}}
Oddmire Pot ({{Coord|54.138109|-2.011044|name=Oddmire Pot}}) is located {{convert|350|m|abbr=on}} north-west of Langcliffe Pot. A small hole in a shakehole leads on to a broken {{convert|17|m|abbr=on}} shaft. At the base of this Strid Passage continues as a crawling / stooping passage for about {{convert|500|m|abbr=on}} before joining Stagger Passage from Langcliffe Pot. An obscure inlet about {{convert|150|m|abbr=on}} from the beginning leads into The Roads, an alternative and longer route to Hammerdale Dub.
Geology and hydrology
Langcliffe Pot is a solutional cave formed within rocks of the Yoredale Series of the Pendlian and Brigantian substages of the Mississippian epoch of the Carboniferous period. The Yoredale Group consists of a number of cyclothems, with sequences of sandstones, shales and thin coals separating limestones into well-defined beds separated by aquicludes. The upper part of the cave is formed at the base of the Middle Limestone and the passages run down dip towards the south-east, floored by sandstone. In Boireau Falls Chamber the stream cuts through the {{convert|50|cm|in|abbr=on|adj=on}} sandstone bed, and then through {{convert|4|m|abbr=on}} of shale into the Simonstone Limestone. Nemesis Pitch drops straight through this, and the Gassson Series is formed totally within the Hardraw Limestone. The resurgence at Black Keld, some {{convert|174|m}} below the lowest point of Langcliffe Pot, lies in the Great Scar Limestone.{{cite book|last1=Waltham|first1=A.C.|last2=Simms|first2=M.J.|last3=Farrant|first3=A.R.|last4=Goldie|first4=H.S.|title=Karst and Caves of Great Britain|date=1997|publisher=Chapman & Hall|location=London|isbn=0412788608|pages=92–95}}
Langcliffe Pot falls within the {{convert|20000|ha}} Black Keld catchment area. Most of the drainage within the catchment feeds into Mossdale Beck which sinks into the limestone at Mossdale Scar. Langcliffe Pot is fed by a few small streams that drain an area of the flanks of Great Whernside about {{convert|500|m}} wide. The water then drains down dip in the general direction of Mossdale. The waters of Mossdale Caverns and Langcliffe Pot combine at some unknown point, and resurge at Black Keld. Black Keld has been penetrated by divers for about {{convert|2|km}}—well short of Langcliffe Pot.
History
Langcliffe Pot was first spotted in December 1935 by members of the Craven Pothole Club (CPC), and they made the first descent the following April when the first {{convert|45|m}} of traverse in the downstream passage was explored to a pool. Soon after, they dye tested the Langcliffe Pot and Rigg Pot streams and various others to Black Keld.{{cite journal|last1=Waterfall|first1=A.C.|title=Rigg and Langcliffe Pots|journal=Journal of the Craven Pothole Club|date=1954|volume=1|issue=6|pages=288–290}} Another party from the same club descended in 1954 and pushed on for a further {{convert|400|m}} along what is now known as Craven Crawl before turning back.{{cite journal |last1=Brindle |first1=N|title=A ¼ Mile extension of Langcliffe Pot, Wharfedale. 13th June 1954 |journal=Journal of the Craven Pothole Club |date=1954 |volume=1 |issue=6|page=290}} In August 1968 a team from the Yorkshire Underground Research Team explored over {{convert|1|km}} beyond the CPC limit as far as the Kilnsey Boulder Crawl. They weren't too impressed with the place, and handed over the baton to the University of Leeds Speleological Society (ULSA). Over the next three months, ULSA explored and surveyed the main stream passage as far as Boireau Falls Chamber, and all the major inlets, giving a total system length of {{convert|6.4|km}}. The next phase of exploration took place in 1970 when the choke in Boireau Falls Chamber was excavated, and Nemesis Pitch discovered. A week later a route was found through the complex boulder choke at the bottom, and a further {{convert|2|km}} of passages discovered. In June 1972 the system flooded whilst an ULSA diving team were on the far side of the Nemesis boulder choke, trapping them which resulted in a major rescue call-out. The party emerged unscathed after a 44 hour long trip. A second major rescue occurred in 1974 when five cavers became trapped on the far side of the Nemesis Choke after boulder movement.{{cite book|title=Anytime... Anywhere|date=1998|publisher=Upper Wharfedale Fell Rescue Association|page=34}}