Somerset Sump Index: Cave Diving Group

By Duncan Price and Michael McDonald

A guide to the flooded cave and mine passages of Somerset, England.

• Language: English
• Publisher: Lulu.com
• Release date: Mar 29, 2011
• ISBN: 9781447552673

Book preview

9781447552673_0001_001

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SOMERSET SUMP INDEX

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fourth edition

compiled by

Michael McDonald and Duncan Price

Copyright

© The Cave Diving Group

2008

Published by the Cave Diving Group

www.cavedivinggroup.org.uk

Copyright © Cave Diving Group 2008

All rights reserved. No part of this publication may be reproduced or transmitted in any form or by any electronic or mechanical means, including photocopying, recording or and information storage and retrieval system without permission in writing from the Cave Diving Group.

ISBN 978-0-901031-05-1

eISBN: 978-1-44755-267-3

First edition compiled by Phil Davies published 1957

Second edition compiled by Ray Mansfield published 1964

Third edition compiled by Michael McDonald published 1991

Fourth edition compiled by Michael McDonald and Duncan Price published 2008

Cover photograph: Chris Jewell emerges from the upstream end of Rubic Sump, Wigmore Swallet by Stuart Gardiner

Introduction

This is the fourth edition of the Somerset Sump Index. The first was produced by Phil Davies in 1957, the second by Ray Mansfield in 1964 which was then revised by Ray in 1977. This edition is based largely upon the third edition (1991) compiled by Michael McDonald and has been brought up to date using reports from the Cave Diving Group Newsletter and other published accounts, as well as contributions from individuals. The format of previous editions has been retained in that a historical synopsis of activities is presented using accounts of original exploration. For more major sites a description of each sump is also provided. Dive reports have been reproduced generally as originally published, although in some cases the text has been edited for brevity. The original units used by the authors (metric versus imperial) have been retained. Please bear in mind that the information contained herein may not be current or accurate. It is the nature of this type of document to become quickly outdated.

Sources of Information

The primary reference work for this publication has been the Cave Diving Group Newsletter (ISSN 1353-713X) produced quarterly. CDG Reviews for the period 1955-68 were also consulted. The popular caving literature (Caves & Caving and Descent) have also provided information as have caving club newsletters and journals. All of the above are referenced in the body of the entry for each site. More general texts for the area comprise local guide books:

N Barrington & W Stanton, Mendip - The Complete Caves and View of the Hills, Cheddar Valley Press, Cheddar, 3rd Edition (1977)

D J Irwin & A R Jarratt, Mendip Underground, Bat Products, Wells, 4th Edition (1999)

The Mendip area is covered by two guides published by the British Geological Survey: A walker's guide to the geology and landscape of Eastern Mendip (ISBN 978 085272 575 7) and A walker's guide to the geology and landscape of Western Mendip (ISBN 978 085272 576 4) which contain location maps and details of many of the caves listed here. Additionally, Chapter 5 of Karst and Caves in Great Britain (A C Waltham, M J Sims, A R Farrant & H S Goldie, Chapman & Hall, London (1997)) affords a review of the geomorphology of the Mendip caves.

Finally, the Mendip Cave Registry and Archive (www.mcra.org.uk) is a useful source of bibliographic information on the sites listed herein.

Acknowledgements

A complete list of contributors would be both lengthy and incomplete - full credit is down to those who recorded their activities in the various sources used for the compilation of this document. Other individuals have been kind enough to supply unpublished information about various sites and have been credited appropriately. Acknowledgement is also given to various cavers and caving clubs for permission to use copyright material such as surveys first published elsewhere. In particular, this includes Wild Places Publishing for material which appeared in Descent. For any further reproduction of such material elsewhere, permission should be sought from the original copyright holder.

The draft text of this publication was read by several people: Tony Jarratt, Alison Moody, Pete Moody and Richard Whitcombe. The compilers are most grateful for their comments and corrections and accept that any remaining errors are our own. In particular, we would like to dedicate this publication to the memory of Tony Jarratt who sadly passed away during the preparation of this manuscript. His advice, encouragement and enthusiasm will be sadly missed.

Finally, many thanks are due to the numerous sherpas and the like who supported the activities documented here. In the interests of consistency and space, the names of supporting cavers have been omitted from the text.

Warning

The exploration of flooded caves and mines is a potentially hazardous activity which should only be undertaken by persons with suitable experience and equipment. Many sites are on private property and the landowner's consent must always be obtained. Whilst every effort has been taken in preparing this document, the Cave Diving Group, the compilers and other contributors accept no responsibility for any errors or omissions. No legal liability is accepted for any accidents or damages sustained for whatever reason.

SOMERSET SUMP INDEX

ASHWICK GROVE RISINGS, Oakhill ST652479

References:

Barrington & Stanton (1977) p.26

WCC Occ. Pub. 2(1):7

Irwin & Jarratt (1999) p.20

There are three risings in this complex; Higher, Middle and Lower. No reports appear to exist for the Middle Rising, although there are references to some diving and digging activities by the MNRC, CSS and WCC since 1960. R A Brown briefly inspected the Higher Rising in 1991. The mean daily flow of the Higher Rising in 1966 was ca. 1.5 million gallons. Middle and Lower Risings have disused Bristol Waterworks machinery nearby. There is an Upper Flood Rising about 30 m upstream of the Upper Rising.

Lower Rising

6 January 1982

Divers: A Boycott, E A Price

A rising which takes water from Blake’s Farm Swallet, Larks Hall Slocker and Midway Slocker. It is capped and undiveable. Six metres south is a small resurgence known as Wishing Well, recently dug open by cavers. The cave is 10 m long. Water enters from a sump under the left wall but is too tight after 1 m.

CDG NL 63:17 (1982)

20 July 1982

Diver: A Boycott

A flake of rock chemically removed from the entrance, now giving access to a steeply descending rift sump 1 m × 0.2 m with a rubble floor. This was descended for 4 m before becoming too tight. Further progress will need digging.

CDG NL 65:16 (1982)

26 & 29 October 1983

Diver: P J Whybro

An interesting descending passage, small and body-sized. Feet first progress with a hand-held bottle to a mud and rock choke after 4 m.

CDG NL 70:27 (1984)

20 October 1991

Divers: R A Brown, M Knapp

Both divers looked at the slot in the floor of the Higher Rising. Being 0.1 m high with a strong flow, it will be a long term dig.

CDG NL 102:17 (1992)

Various dates

Divers: P Bolt, P Mulholland, M Barnes

(The dive report is for Ashwood Close Risings - it is believed the divers mean Ashwick Grove Risings).

Upper Rising: (10.4.94, 17.5.94, 28.5.94)

Digging out the resurgence floor enabled the 5 m long sump to be converted into a duck. Further digging at the end revealed a small rift in the right hand floor issuing the stream. Rock demolition at this point has revealed an ongoing rift, 15 cm wide, that can be seen to go for 2 m to a left turn where the stream can be heard flowing.

Upper Flood Rising: (10.4.94, 17.5.94, 28.5.94) Digging at the base of a well-choked pile entered a low bedding that was dived for 5 m to a second choke. This find was later confirmed as having been previously dug when dry with the same conclusion.

Lower Rising: (28.8.94, 2.10.94) The most interesting of the four sites. A small cave enters a short rift, the end of which comprises a sump descending in a 0.6 m diameter tube. About 6 m of progress is possible to a point where the passage levels and the way on can be felt 10-15 cm high over boulders and mud. An over-equipped attempt to dig this point failed, much to MCM's amusement.

CDG NL 117:23 (1995)

2003

Divers: T Chapman, A Stuart, P Mulholland

A series of dives in this shallow resurgence, using air drills, electric drills, digging kit and explosives.

CDG NL 149:25 (2003)

ASSOCIATE’S POT, Priddy ST549512

28 September 1969

Diver: A D Mills

Mined 30 ft. shaft to water. AM dived for approximately 15 ft. into a small chamber with three passages leading off. AM explored two of the passages: the first one ended in a tight bedding plane about 6 ft. in, the second went for 15 ft. into a small chamber with three passages leading off. AM followed the one on the floor for about 10 ft. where it became too tight to follow.

A Mills, Personal Log (with survey)

21 December 1969

Diver: A D Mills

AM dived to bottom of Pot but the roof had collapsed.

A Mills, Personal Log

A Jarratt, Personal Log

AXBRIDGE OCHRE CAVERN, Axbridge ST431551

References:

Barrington & Stanton (1977) p.28

UBSS Proc. 5(3):191

Irwin & Jarratt (1999) p.22

11 May 1983

Diver: P J Whybro

Aim to investigate pools in the floor of the natural cave. Maximum depth 2 m. No progress and no future here.

CDG NL 68:23 (1983)

AXBRIDGE RISING, Axbridge ST431546

References:

Barrington & Stanton (1977) p.29

Mendip Caver 2(12):93

Located behind a wall at the back of dammed pond in private garden north of Axbridge Square. A large spring with no proven feeders which ceases to flow in long, dry weather.

6 September 1963

Observer: M M Thompson

Examined without equipment this important but little known rising. A strong stream rises under a masonry arch through small boulders with no direct entry.

CDG Review (1963) p.16

AXBRIDGE STATION WELL, Axbridge ST 431551

Possibly related to the above rising, this well, now buried under the Axbridge bypass. Its location was about 60 m north of the above site and at 60 m altitude.

9 June 1966

Diver: M J Wooding

A seven foot diameter well 200 ft behind the Axbridge Rising was descended 54 ft to water. This was found to be 8 ft deep with a level muddy floor and from it a natural passage led into the hillside becoming too tight after 10 ft.

CDG Review (1966-67) p.3 Somerset Section NL June 1967(1)

BALCH CAVE

See Conning Tower Cave.

BANWELL STALACTITE CAVE, Banwell ST383588

References:

J W Hunt, Banwell Leer, Deep or Stalactite Cave ACGJ (1970) p.1 M Clarke, A brief history of the Banwell Stalactite Cave, WCCJ 13(161):250 Barrington & Stanton (1977) p.35 Irwin & Jarratt (1999) p.25

1 July 1975

Divers: P J Lord, R A Stevenson

The lake in Green Lake Chamber was dived only to find that it is as unstable underwater as it is above. The divers reached a rift which they descended for 20 ft to a tight cross rift.

CDG NL 37:21 (1975)

15 March 1987

Diver: M R Owen

Aim to explore the boulder choke for a possible route on. Good visibility allowed a thorough examination of the boulder chamber but with no leads noted.

CDG NL 84:13 (1987)

The water table can fluctuate over 12 m vertically in Green Lake Chamber.

BLAKE’S FARM SWALLET, Oakhill ST 646469

References:

Barrington & Stanton (1977) p.42 WCCJ 6(82):319 Irwin & Jarratt (1999) p.28

This area was investigated on 2 July 1960 by M M Thompson, J Hanwell, J Wright and B Prewer following original exploration by C Falshaw.

SMCC Caving Logs

13th November 1978 Divers: C N Milne, R C Harper

To investigate a reported sump found last summer after the passing of a choke.

Unpleasant short carry to a sump pool 10 ft in diameter. Constricted passage leading down through boulders for about 12-15 ft to a choke consisting of mud and small stones. No other openings found.

CDG NL 50:13 (1979)

This cave was dye-traced in 1973 to Ashwick Grove Middle Rising, travel time 7 hr.

CAIRO SHAFT, Compton Martin ST530561

Reference:

Irwin & Jarratt (1999) p.43

A mid 19th century iron mine, partly natural. A shaft opens into an inclined steeply descending rift with a flooded downstream passage beyond a mud choke.

29 November 1997

Diver: K N Savory

KS dived the flooded passage, but found the way on too constricted after 15 ft.

ATLAS Log

CANNARD’S WELL, Cannards Well Inn, Shepton Mallet ST626418

6 September 1989

Divers: K N Savory, P L Brooke, D W Pike

The well is located in the main bar of the pub and the landlord wanted some lights changed. Decompression at +1 m standing at the bar (Cordingley/Carter tables).

CDL NL 94:28 (1990)

CHARLTON WELL, Shepton Mallet ST628431

Reference:

Barrington & Stanton (1977) p.49

18 December 2004

Diver: J Beal

The diver had been asked to dive in a well at Frampton's Foods, where water is pumped for the factory's use. A rope access team have been drilling in an adit to increase the water flow into the well, which is on the lower edge of the Mendip plateau and was dug around a century ago. While working, a gas monitor and a large torch had been dropped into the water and needed recovering. Diver and support abseiled 55 m down the 2 m diameter shaft between two water pipes to access the adit at the water level. Diver then kitted up to enter the water with pony cylinders and no fins to squeeze between the pumps to a depth of only 6m to recover the items. Initial visibility was excellent allowing another adit to be seen. This was half-full with silt but was followed for 10 m to a 90 degree bend where a blasted face was found. A slow prussik out introduced the diver to the joys of double ropes and shunts.

CDG NL 154:12 (2005)

CHARTERHOUSE CAVE, Charterhouse ST478562

References:

Irwin & Jarratt (1999) p.44 Descent 204:14 (Oct/Nov 2008)

At the end of February 2008 Charterhouse Cave was extended. A boulder choke was passed to gain a further 130 m. of stream passage which then joined water from G.B. Cave beyond that system’s final choke. The combined streamway can be followed through big passage for another 250 m. to an active sump at 69 m.

O.D. 43 m above the known resurgence of Cheddar Risings. At a depth of 175 m. a short climb out of the streamway leads to a low crawl which opens out into a large, long-abandoned, phreatic tunnel (The Timeline), which runs parallel to the streamway, descending gently for 70 m terminating in a static sump at 73 m O.D. (some 4 m above the level of the main streamway sump) and displaced about 30 m away to the north east.

Streamway Sump

28 June 2008

Diver: P Moody

Probing without diving kit showed it to be shallow and there was no evidence of it backing up in the spring and early summer floods. Unfortunately this reconnaissance dive quickly established it was not going to be a simple, short, easy dive into Charterhouse Two. The sump was found to be reasonably wide, but very low and it took the diver some while to actually get completely underwater. The start is constricted, the floor dips gently and the fine silt quickly results in blackout conditions. With the passage appearing to continue uncomfortably tight the diver retreated, having gained at most 4 m of progress.

CDG NL 169:13 (2008)

21 August 2008

Diver: P Short

Wearing 2 × 2 l sidemounted cylinders the diver entered the sump head-first with the reel in the left hand. The passage sloped down at a gently angle and was low (approx 40-50 cm) but wide (beyond reach of divers outstretched arms). The passage floor was large gravel and cobbles in the centre and silt and mud to the sides. The roof was uneven with many pendants.

PS followed the centre of the passage in the main water flow down slope at a very gentle angle until the ceiling lowered, restricting passage height (to approx 25 cm), and halting forward progress. This was approximately 4-5 m into the sump. At this point the diver’s equipment restricted further progress and leaving the line reel the exit was not as straight forward as hoped as the roof pendants continually snagged the divers harness. Eventually a contortion to free the harness from the roof forced the divers face into the gravel floor (filling the second stage exhaust with small stones) causing a free flow (noticed by the support team). The diver switched regulators, isolated the faulty valve and freed the stones before turning the valve back on and continuing his exit. The diver surface after 8 minutes of dive time to a maximum depth of 0.8 m.

After a hasty re-think the diver opted to have another attempt at the sump with a 'no-mount' hand held configuration (as used previously by the diver on the Swildon’s 12 digging project). The cylinders were removed from the harness and 'banded' together with snoopy loops, 1second stage in the mouth and the other to the divers neck strap. The diver pushed a dive light up each sleeve of the wetsuit (creating a wrist mount light system) and the diver’s helmet was removed.

Following the existing line the diver returned to the reel and continued further in to the continually shrinking passage, rolling the reel ahead of him. Passage now was pinching the divers chest and shoulders between floor and ceiling (approx 20 cm height) and the diver had to make progress with the head on one side. Also the wide passage of the entrance was closing in so now the diver could reach to the left and right up low silt banks to the passage walls. The floor in the centre of the passage (with the main water flow) was now a thin layer of fine gravel over bedrock (so no chance of digging to enlarge and facilitate progress).

At this point the diver managed to get the reel (an arm’s length ahead of him) wedged between floor and ceiling approximately 8-9 m into the sump from base, and a retreat to base was made. The diver surfaced after 5 minutes of dive time to a maximum depth of 0.8 m.

After a brief discussion with the support team the diver entered the sump a third time to attempt to retrieve the reel but could only just reach the edge of the reel with his fingertips. He was unable to get enough purchase to pull it out of where it was jammed so a final exit was made.

CDG NL 169:13 (2008)

Static Sump

3 May 2008

Diver: P Moody

A spacious airbell, with an aural connection to base, could easily be ducked into on the northern side however underwater all ways ended in blind alcoves.

Although the sump is not tight, the line reel used by the diver was grossly disproportionate to the size of the passage and was a real nuisance.

CDG NL 169:14 (2008)

20 September 2008

Divers: P Moody, J Maneely

Today’s dive was to take a second look using a base fed line. JM acted as linesman for PM, who again could find no way on. The furthest point reached some 4 to 5 m. from base at negligible depth. JM, on a tourist trip to the Charterhouse extensions and wearing only a neo-fleece (being young and keen) borrowed a hood and diving gear to take a look as well. Confirming PM’s findings, JM thought a closer inspection of the southern wall using a small search reel might be in order before writing off the sump.

CDG NL 169:14 (2008)

CHEDDAR RISINGS, Cheddar ST466539

References:

W I Stanton,Odds & Ends (Saye’s Hole and the Cheddar Underground River), Wessex CCJ 9(111):203 (1967) Wessex CCJ 51:16 (1955) Barrington & Stanton (1977) p.50

Survey:

W I Stanton (1965) grade 6b (separate sheet)

All the water rising at Cheddar emerges from the true left hand side of the Gorge at several well defined points relatively close together. The highest of the risings in normal weather is the First Feeder, which often fails in dry weather, but which has a mean daily flow of 18 million gallons. A few yards further down the gorge, a smaller though quite considerable stream, the Second Feeder, rises under the same cliff. This one seldom fails. The numerous other smaller risings have been diverted into artificial channels which conduct the water under the road into the lake. The greater part of the water rising at the First Feeder emerges from amongst boulders which obstruct the floor of the arched recess in the cliff behind the Cave Man Restaurant. Proved feeders for this rising include Blackmoor Swallet, GB Cave, Longwood Swallet, Manor Farm Swallet, Pinetree Pot, Wigmore Swallet and Attborough Swallet. From the evidence obtained during the diving attempt in 1955, it would seem that many tons of rock would need to be removed before any onward progress could be made.

First