Dow Cave - Providence Pot

"Not far away [from Kettlewell] are a couple of large and interesting caverns in the limestone, called Douk and Dove Caves. ... But their precise extent and direction have never been ascertained, the exploration being decidedly difficult [and] not without danger." — Harry Speight, "The Craven and North-West Yorkshire Highlands" (1892).

This article reports the completion of a long-standing project to resurvey the Dow Cave – Providence Pot system, including the unique, nearly-mile-long Dowbergill Passage. (The earlier name was 'Dowber Gill Passage' but the usage here follows Northern Caves.)

Brief history

The exploration of Dowbergill Passage, and subsequent discovery and exploration of Providence Pot, were perhaps the crowning achievements of a very productive post-war period for the CPC – a period which also included the exploration of Car Pot in 1948, and the discovery of the Caseker Gill extensions in Dow in 1953.

Following the latter discovery, a positive flourescein test from sinks in Dowber Gill proved the likelihood of at least a mile of unexplored cave passage. However, the dye arrived not at the terminal choke in the new extensions, but at an obscure side passage in the original cave just short of the Hobson's Choice boulder choke. Thus was the entry to Dowbergill Passage uncovered, although in fact the Burnley Caving Club had got at least as far as siphon chamber in 1953 [see "P.G. not D.G.", S. E. Warren, CPC Journal 6 (4), 194-5 (1982-3)].

By 1954 progress had been made as far as Bridge Cavern (see accompanying glass 'lantern' slide image) but the severity of the trips prompted further examination of the sinks in Dowber Gill, resulting in the opening up of Providence Pot, named after the Providence lead mine above the sinks. Finally, the connection between Providence Pot and Dow Cave was made on 21st May 1955 by a party comprising Dennis Brindle, Norman Brindle, Norman Clarkson, Arthur Hardy, Bob Powell, Brin Powell, and Steve Warren. The first actual traverse (from Dow to Prov) was made soon afterwards by Bob Powell and Norman Brindle, in a 7.5 hour overnight trip.

It is a testament to these CPC 'tigers' that Car Pot and Dowbergill Passage are both still regarded as worthwhile, hard caving trips. Both feature in "Not for the Faint-Hearted" – Mike Cooper's book of selected harder caving trips in Yorkshire. This book contains an excellent and detailed description of the main route, and various off-beat alternatives, and supplements the otherwise rather spartan description in Northern Caves. Armed with these descriptions, and the new surveys, the modern explorer is well equipped for the expedition, though certainly the rifts downstream of 800 yds Chamber remain a challenging vertical puzzle. It is important not to underestimate the arduous nature of the traverses, and to be aware that loose rock remains a hazard in various places. In particular, at the climb up through the large boulder pile at the midway point in Bridge Cavern, the large (fridge-sized) boulders are still on the move, even 60 years after the original exploration. Steve Warren recalls in the 1950s Bob Powell being chased back up the passage by one of these boulders, and in 1972 there was a serious accident at this point.

Previous surveys

This can be very brief! To my knowledge only the 1954-5 surveys of Dowbergill Passage are original, and all subsequent published surveys are based on these. The survey from the Dow end as far as Bridge Cavern was published in CPC Journal 1 (6), and a separate survey of Providence Pot including Dowbergill again as far as Bridge Cavern was published in CPC Journal 2 (1). It's curious that no combination survey was ever published at the time, but that may reflect a difficulty in matching up the ends since it turns out the survey from the Dow end considerably underestimated the length (by 60-70 m, as we shall see). Also, to my knowledge, an elevation has never been published.

The resurvey project

The project was started (accidentally!) in 1982 with a survey of Dow Cave as far as Hobson's choice. This was actually an exercise to generate data for an early cave survey computer program, but that is another story. The Dow survey continued in fits and starts throughout the 1980s until the Caseker extensions and all the side passages had been done. Then a major push by the WRPC in 2003-4 saw Dowbergill Passage surveyed through the Narrows as far as 800 yds Chamber. After that, all of Providence Pot, and the passage upstream of Stalagmite Corner, were ticked off in a series of trips in the period 2005-2010. This left only the long section between 800 yds Chamber and Stalagmite Corner to be done. There things lingered for several years... Eventually (2015) I had sufficiently sold the pleasures of Dowbergill to Carmen Smith that she volunteered to come up from Dorset (not once but twice!) to help finish the job off.

The new survey

The new survey can be regarded as comprising: (i) a set of survex data files, and (ii) the drawn up surveys. The survex data files contain details of the survey parties and trip dates, and are now on the Cave Registry Data Archive under Wharfedale in the Northern England data sets. Drawn up surveys for Dow Cave, Providence Pot (including upstream of Stalagmite Corner), and Dowbergill Passage (from Dow to 800 yds Chamber) are collected on Steve Warren's personal website. The newly drawn up survey for Dowbergill Passage from 800 yds Chamber to Stalagmite Corner accompanies this article, and is published here for the first time.

I have also used the fact we now have a continuous surveyed centreline through the system to produce a new overall plan and elevation which also accompanies the present article. The elevation also includes a surface profile generated from the Ordnance Survey OS Terrain 50 surface altitude dataset.

From the survex data files one can generate the tables accompanying this article.

The Dowbergill Passage centreline contains some duplicate sections where one can traverse (or not) above the water level, such as Gypsum Traverse. However it seems to the present author these are genuine alternatives and have been included in the length total in Table 1. For an alternative picture, projected lengths are reported in Table 2.

Historically, Providence Pot was classed as from the entrance to Stalagmite Corner, and the rest was classed as Dowbergill Passage, part of Dow Cave [see N. Brindle, CPC Journal 2 (1), 4-9 (1955)]. I have adopted this convention here, so that the passage upstream of Stalagmite Corner is included in the Dowbergill length, and excluded from Providence Pot length. Otherwise Providence Pot survey includes all the significant side passages. Northern Caves previously reported the length as 344 m, which now appears to have been a considerable underestimate.

The altitude gains in Table 2 are calculated using convenient survey stations in the indicated positions, and thus overstate changes in floor (water) level, but by no more than a couple of metres.

Perusal of the elevation data in combination with the surface profile reveals that the deepest part of Dowbergill Passage is around the start of the Narrows, downstream of 800 yds Chamber. At this point the depth is about 150 m (or 80 fathoms in proper units). Also, Dowbergill Passage does indeed run nearly exactly underneath Hag Dyke (the offset of which is about 15 m WSW), and the depth at that point is about 110 m (60 fathoms).

An obvious question concerns the accuracy of the new survey. The misclosure in the main traverse is about 1.5% which is a little large for the claimed grade 5 survey. However there appears to be a systematic compass calibration error of a couple of degrees. If this is removed by hand, the misclosure falls to a respectable 0.7% – about 15 m horizontally, and 4 m vertically. The entrance coordinates correspond to the expected positions on Magic Map but GPS inaccuracies may account for several metres of the horizontal misclosure. The altitude of Providence Pot entrance is taken from GPS and confirmed by the OS Terrain 50 dataset. The altitude of the Dow Cave entrance survey station was fixed by levelling from a bench mark at Park Rash (Bob Cross & Steve Warren, Easter 1986). Magnetic declinations were recalculated for all datasets using the IGRF model available online at the NOAA website.

800 yds Chamber discrepancy

Obviously as soon as the centreline was completed we were eager to compare with the existing surveys. This immediately threw up a mystery since it appeared that 800 yds Chamber was some 60 m out of position in the new survey. After some consternation, we realised that this would imply an almost miraculous cancellation of an unlikely 60 m error in each of the two separately surveyed halves of Dowbergill Passage. The situation was only really resolved when we acquired some radio-location (R/L) data from our UWFRA contact Andy Cole. Whilst the R/L data requires careful interpretation, it does appear to confirm that 800 yds Chamber really was out of position in all the previously published surveys (see Table 3). The error was presumably propagated from the original 1954 survey.

What next ?

A single combined survey has been produced from all the various pieces and will appear in the forthcoming Book of Dow.

Acknowledgments

In addition to Carmen, I thank Becka Lawson and Andrew Atkinson for accompanying me on a follow-up trip to check passage details. I also thank Simon Beck for a helpful and independent evaluation of the new survey.

Click on the surveys below to obtain PDF versions

Adapted from CPC Record 122, 11-15 (2016).

Copyright © (2016) Patrick B Warren and Craven Pothole Club Ltd.