West, Ian M. 2019. Burrington Coombe - Geological field guide. In preparation; Supplement to Geology of the Wessex Coast. Internet site: www.southampton.ac.uk/~imw/Mendip-Hills.htm. By Ian West, Romsey, and School of Ocean and Earth Science, Southampton University. Version: Revised 16th January 2019.

Geology of Burrington Coombe, Mendip Hills

Ian West,
Romsey, and
Faculty of Natural and Environmental Sciences,
Southampton University,
Webpage hosted by iSolutions, Southampton University
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Related Webpages:

Index list of these geological webpages
Cheddar Gorge
Geological Bibliography of Carboniferous Strata

CONTENTS

1. INRODUCTION
2. SAFETY
3. AERIAL PHOTOGRAPHS
4. TOPOGRAPHIC MAPS
5. GEOLOGICAL MAPS AND CROSS-SECTIONS
6. SEQUENCE OF CARBONIFEROUS STRATA
7. INTRODUCTORY FIELD PHOTOGRAPHS
8. CAVES OF BURRINGTON COMBE
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1. INTRODUCTION

[NB. THIS WEBPAGE IS IN PREPARATION AND IS INCOMPLETE, Jan 2019]

Burrington Combe is a valley and gorge cut into Carboniferous Limestone (Lower Carboniferous). It is rather similar to Cheddar Gorge (only a short distance away), but on the north side of the Mendip Hills rather than on the south side. It is smaller than Cheddar Gorge. However, it is not commercialised, as is Cheddar Gorge, and does not usually have numerous cars and coaches. It is a much quieter place. There is car-parking in an old quarry near the "Rock of Ages" (the steeply-dipping limestone and dolomite that inspired the well-known hymn that was written by the Reverend Toplady in 1763). The geology is very interesting and the exposures of the Lower Carboniferous limestone are good. The Burrington Oolite and associated dolomite and overlying limestone is well-exposed. Burrington Combe is a notable place for caving (speleology) but it does not have illuminated caves and guided tours for the general public. The geological history of the caves is quite complex. The flow of groundwater is quite complex and there are the interesting features of resurgences.

[At present this webpage is only in a preliminary stage of preparation and new photographs, diagrams and more detail should be added soon - 1st January 2019, Ian West]

The main Ordnance Survey Map, strongly recommended for purchase, is: Cheddar Gorge and Mendip Hills West (Wells and Glastonbury), scale 1: 25,000 or 4cm to 1km (2.5 inches to one mile). The relevant geological map is the British Geological Survey, England and Wales, Solid and Drift Edition, Cheddar Sheet (England and Wales, Classical Areas of British Geology, Sheet ST 45, 1:2500 Series, published in 1966, and reprinted with minor additions in 1993).

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2. SAFETY

There are certain specific risks at Burrington Combe. The caves are not illuminated or guided and some expertise and the ability to crawl through long low passages may be needed. The entrance ways are easily accessible but penetrating far into the caves should be left to expert cavers (speleologists). The caves can be dangerous and this webpage does not give details on the subject. One of the main risks to geologists is that of falling falling from a face of very hard and angular limestone rock. Climbing the rock can be dangerous. Take particular care during any activity on this hard and angular rock. Do not, in any circumstances, hammer chert because it can produce very dangerous, high-velocity splinters. If you are studying the strata of the combe take care with regard to passing road traffic. The road is fairly narrow and is without well-defined, side footpaths. Park your vehicle only in a safe place such as the old quarry car park in the lower part of the combe.

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3. AERIAL PHOTOGRAPHS

Aerial view of Burrington Combe, based on GoogleEarth

An oblique, northward, aerial view of Burrington Combe, based on GoogleEarth

The road from the Mendip Hills descends into Burrington Combe alongside the Great Scarp of Black Rock Limestone, photograph by Roger Cornfort, with modifications

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. 4. TOPOGRAPHIC MAPS

A large-scale topographic map of Burrington Combe

Recommended purchase: Ordnance Survey Map: Cheddar Gorge and Mendip Hills West (Wells and Glastonbury), scale 1: 25,000 or 4cm to 1km (2.5 inches to one mile).

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5. GEOLOGICAL MAPS AND CROSS-SECTIONS

A simplified, redrawn, general geological map of part of the Mendip Hills area, to show the structure and its relationship to Cheddar Gorge and to Burrington Combe, Somerset, based mainly on old geological maps

Above is the very simplified geological map of the Mendips and the area around Cheddar Gorge and Burrington Combe. It has been completely redrawn, largely based on old maps, but with some updating of nomenclature. No topography is shown.

A geological, north-south, cross-section through the Blackdown Pericline, Mendip Hills, including both Cheddar Gorge and Burrington Combe, completely redrawn at different scale after a BGS section

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A geological map of Burrington Combe, completely redrawn in colour, and with minor modifications and additions, after Green and Welch, 1965

An old, simplified, geological map of Burrington Combe, with some additions to explain the lithology, revised version re Aveline Hole

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6. THE SEQUENCE OF CARBONIFEROUS STRATA

A correlation diagram for the Lower Carboniferous strata from the Avon Gorge to Burrington Coombe to Cheddar Gorge, Mendip Hills, Somerset

A vertical section of the Lower Carboniferous strata at Burrington Coombe, as shown in old traditional terminology, and with comparison to other sections in the region, including that of the Avon Gorge

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7. INTRODUCTORY FIELD PHOTOGRAPHS

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A view down into Burrington Combe from the hill above, after William, Geograph, slightly modified

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Looking at the lower part of Burrington Combe with exposures of Burrington Oolite limestone, including the Rock of Ages, on the right

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The Rock of Ages in Burrington Combe in old and new photographs, actually a stream-cut exposure of north-dipping, Burrington Oolite of the Lower Carboniferous Limestone

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The conspicuous rib or projecting bed of dolomite in the Burrington Oolite, Quarry 2, east side of lower part of Burrington Combe

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Students taking dip readings just stratigraphically below the dolomite bed, or rib, in the Burrington Oolite, Burrington Combe, 1997

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8a. CAVES OF BURRINGTON COMBE

8a - Aveline's Hole

The middle part of Burrington Combe with the entrance to Aveline's Hole, an easily accessible cave, on the left of the picture

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At the entrance to Aveline's Hole, a cave by the roadside,  a short distance north of the car park in Burrington Combe

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Aveline's Hole is an easily accessible cave by the roadside on the east side of Burrington Combe, a short distance upslope from the car park. It is not an organised show-cave but a natural cave with an entrance near to the road level. Stratigraphy and problems have been discussed by Donovan (2005). It is probably a former resurgence feature, low down in the valley. It is situated just south of the car park, in an old quarry, and is on the east side of the road, not far upslope from the Rock of Ages (west side of valley).

The cave consists of a single passage about 50m long and running east-west. It is a relict resurgence which originated a large phreatic tube [i.e. under water] running along the strike of the Burrington Oolite. The roof has been modified by rock falls but solution features have been seen in the roof of the outer chamber. They show that the cave has been filled with water and that there has been flow in an upward, westerly direction. Thus, when formed it was not an open cavern at the side of the Combe, but was an active, water-filled tube (thus it was phreatic). Because of this it was presumably formed by underground, flowing water before Burrington Combe was fully eroded down to the present level. It was not formed as some sort of open cavern at the side of a stream down Burrington Combe; it has an older history. Presumably the gorge has cut down into this underground water course, rather later in its history.

There has been much study by J.A. Davies and others in papers in the Proceedings of the University of Bristol Speleological Society (fortuntately, many such papers are easily available online now). As much as 150 tonnes of deposit (about a metre of thickness) was removed from this cave for study by 1925.

A stalagmite layer or "Stalagmite Shelf" was "full of human bones" according to Davies (1924, p. 6). See: Davies, J.A. 1924. Third report on Aveline's Hole. Proceedings of the University of Bristol Speleological Society, vol. 2, part 1, pp. 5-15. This describes a stalagmite shelf "full of human bones". There was a shattered human tibia, a young left femur and humerus, an adulf femur in two halves and an ulna. A child's skull was found 15 cm belwo the surface. Human teeth, fragments of long bones, hand and foot bones, were found in stalagmite adhering to the cave wall... Davies thought that the cave mouth had been blocked by a rock fall in very late Palaeolithic times, because no later artefacts or fauna had been found, and that the "stalagmite grew apace".

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8b. CAVES OF BURRINGTON COMBE

8b - Goatchurch Cavern

At the entrance to Goatchurch Cavern, Burrington Combe, in 1998

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Plan-view map of Goatchurch Cavern, Burrington Combe, based on Tratman,1963, but redrawn in colour and with some geological information added

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In The Drainpipe, a narrow phreatic passage deep in Goatchurch Cavern, Burrington Combe, Mendip Hills, with Ian West in about 1950, and more recently

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An old photograph of the entrance to Goatchurch Cavern, Burrington Combe, in about 1903, when it was, at least in part, a show-cave

Above is a very old photograph of the entrance to Goatchurch Cavern, at a date when it was a show cave. The distant, deep passage is very narrow and difficult crawl, and perhaps only the safer first part, much wider, was open to the public.

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[LOWER LIMESTONE SHALE LOWER LIMESTONE SHALE GROUP (LSH) - work in progress]

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Avon Group (Lower Limestone Shale) Avon Group (Lower Limestone Shale) The Avon Group (or Lower Limestone Shale), is up to 150 m thick in the western Mendips. The dominant lithology is fissile mudstone with limestone interbeds. The mud-rich nature of the succession reflects the environmental transition from arid desert to shallow sea. Conditions were too turbid to allow the growth of corals, which are a feature of much of the lower Carboniferous succession, but other marine fossils such as crinoids, brachiopods and bryozoans became well-established and are a significant component of limestones in the lower part of the succession, including a marker-horizon known as the 'Bryozoa Bed'. Ripples, scours and cross-bedding in the limestones show that deposition occurred in a shallow, high energy environment, and some of the limestones are distinctly reddened due to high concentrations of the iron mineral haematite. The higher part of the formation contains greenish-grey shales and black crinoidal limestones, which were probably deposited in a slightly more open-water marine setting.

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REFERENCES - BURRINGTON COMBE GEOLOGY AND GEOMORPHOLOGY

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Baker, E.A and Balch, 1907. [Ernest A. Baker and Herbert E. Balch] The Netherworld of Mendip; Explorations in the Great Caverns of Somerset, Yorkshire, Derbyshire and Elsewhere. 167pp, with photographs. See pp. 99-105, The Burrington Cavern.
Example extract from p. 100 to 101: "Half-way up the gorge makes a sudden bend towards the east, a little below which a shallower ravine comes in on the other side. About 120 feet above the bed of this dry ravine is the entrance to Goatchurch Cavern. We coaxed the horse over the stony turn and up the ravine till the roughness of the ground and thickness of bramble bushes stopped him. At this point we were met by the Lord of the Manor, Mr. James Manford of Langford, who is the owner of the Burrington caves. His men assisted us to get our apparatus up to the cave mouth, and afterwards convoyed us and the luggage throughout the less difficult parts of the cavern." [continues to p. 103]

British Geological Survey Burrington Combe Webpage. Extract: "Burrington Combe is a fine example of a typical Mendip gorge, and provides a well exposed, easily accessible, section through the Carboniferous Limestone sequence. The oldest rocks are exposed in the East and West Twin valleys draining Blackdown, and show the transition from the older Devonian sandstones of the Portishead Formation through the limestone and mudstone of the Avon Group to the younger marine Carboniferous Black Rock Limestone, which are very well exposed in the upper part of Burrington Combe. The rest of the Carboniferous Limestone sequence is exposed in the Combe." continues..

British Geological Survey. 20-? undated. The BGS Lexicon of Named Rock Units - the Avon Group; Courceyan Substage, CF.
See for example: "Lower Limestone Shale" - Traditional Name [some short notes only given here; go to full BGS account for more information]. Grey mudstones and thin-bedded shelly limestones [skeletal packstones]. Lower Boundary: Conformable in southern settings, where it is taken at the sharp to gradational incoming of grey calcite mudstones, mudstones and limestones of the Group, above the red sandstones, siltstones and mudstones of the Upper Old Red Sandstone. Upper Boundary: Gradational in southern settings, and taken at the incoming of dark grey, skeletal packstones [i.e. dark grey, shell debris limestones] .. of the Black Rock Limestone Subgroup]. Age Range - Courceyan Substage (CF). Of the Carboniferous Limestone Supergroup. Thickness - 156m in the south Mendip Hills, thinning northwards to 96m in the Bristol area, 54m in the Monmouth area. Former Names - Lower Limestone Shale, Lower Limestone Shale (LSH).

Davies, J.A. 1921. Aveline's Hole, Burrington Coombe. An upper Palaeolithic station. Proceedings of the University of Bristol Spelaeological Society, vol. 1, part 2, pp. 61-78.

Davies, J.A. 1923a. Second report on Aveline's Hole. Proceedings of the University of Bristol Spelaeological Society, vol. 1, part 3, pp. 113-125.

Davies, J.A. 1923b. Exploration of Aveline's Hole, Burrington Combe, Somerset. British Association for the Advancement of Science. Report of the Ninetieth Meeting, Hull, 1922, p. 388.

Davies, J.A. 1923c. Aveline's Hole, Burrington Combe: an upper palaeolithic station. Proceedings of the Somerset Archaeological and Natural History Society, vol. 68, part 2, pp. 21-26.

Davies, J.A. 1924. Third report on Aveline's Hole. Proceedings of the University of Bristol Speleological Society, vol. 2, part 1, pp. 5-15. This describes a stalagmite shelf "full of human bones". There was a shattered human tibia, a young left femur and humerus, an adulf femur in two halves and an ulna. A child's skull was found 15 cm belwo the surface. Human teeth, fragments of long bones, hand and foot bones, were found in stalagmite adhering to the cave wall... Davies thought that the cave mouth had been blocked by a rock fall in very late Palaeolithic times, because no later artefacts or fauna had been found, and that the "stalagmite grew apace".

Davies, J.A. 1925. Fourth report on Aveline's Hole. Proceedings of the University of Bristol Speleological Society, vol. 2, part 2, pp. 104-114.

Dawkins, W.B. 1865. On the caverns of Burrington Combe, explored in 1864, by Messrs. W. Ayshfor Sanford and W. Boyd Dawkins. Proceedings of the Somerset Arcaheological and Natural History Society, vol. 12, pp. 161-176.

Dawkins, W. B. [W. Boyd Dawkins] Cave Hunting. 1874. [reprinted in 1973 by EP Publishing Ltd., with a foreword by D.C. Mellor]. Full Title: Cave Hunting, Researches on The Evidence of Caves Respecting the Early Inhabitants of Europe. Macmillan and Co. 1874, 455pp. [There is only limited information on the Mendips in this book; there is no detail regarding Burrington Combe, but much more on Wookey Hole. See p. 292 et seq. - "Caves of the Mendip Hills"; a small extract is given below:]
"... The fauna of the Mendips is, however, characterised by the great number of lions [the Mendip lions were larger than those in Africa today], and by few fragments of the glutton" [i.e. the Wolverine, a heavily built but short-legged carnivorous mammal with a long brown coat and a bushy tail, native to the northern tundra and forests in Eurasia and North America.]

Donovan, D.T. 1955. The Pleistocene deposits at Gough's Cave [Cheddar Gorge], including an account of recent excavations. Proceedings of the University of Bristol Speleological Society, vol. 7, part 2, pp. 76-104. [Aveline's Hole is compared to Gough's Cave which is in Cheddar Gorge.]
Abstract: The stratigraphy of the Late Quaternary deposits is described. There is similarity to the sequence at Gough's Cave, Cheddar. At both sites cave earth yielded late Upper Palaeolithic flint tools together with human and animal bones, and is succeeded by stalagmite which began to be formed about 9000 BP. The cave earth at Aveline's Hole was extensively reworked after its deposition, and the depths of finds does not offer information as to their relative ages.

Donovan, D.T. 2005. Aveline's Hole, Burrington Combe, North Somerset: Stratigraphy and Problems. Proceedings of the University of Bristol Speleological Society, vol. 23, pp. 159-170. [have copy]
Abstract: The stratigraphy of the Late Quaternary deposits is described. There is similarity to the sequence at Gough's Cave, Cheddar. At both sites cave earth yielded late Upper Palaeolithic flint tools together with human and animal bones, and is succeeded by stalagmite which began to be formed around 9000 BP. The cave earth at Aveline's Hole was extensively reworked after its deposition, and depths of finds does not offer information as to their relative ages.

Farrant, A.R., Mullan, G.J. and Moody, A.A.D. 2008. Speleogenesis and Landscape Development in the Burrington Area, Somerset. Proceedings of the Bristol Speleological Society, vol. 24, part 3, pp. 207-252.
Abstract: The Burrington area of western Mendip is well known for its caves and contains over 3.7 km of surveyed passage. The typical Burrington cave consists of a network of predominantly small phreatic tubes generally aligned along strike and developed at certain preferential elevations, linked by steeply descending vadose caverns. Many of these passages are partially sediment choked. The speleogenesis of these cave systems is governed largely by the geological structure, the rate of erosion of the Mercia Mudstone in the Vale of Wrington and locally modified by the sediment influx off the northern slopes of Black Down. Several well-developed former water-tables, analogouse to those seen in the caves on the southern side of Black Down. Several well-developed former water-tables, analogous to those seen in the caves on the southern side of Black Down can be identified at elevations of 166-160 m, 151 m, 140 m, 127 m, 115 m, and 116 m AOD. A summary of the hydrology of the Burrington area is given and an estimate of the age of the caves estimated. [end of abstract]

Fawcett, E. 1920. Report on material found at the "The Cave", Burrington. Proceedings of the University of Bristol Spelaeological Society, vol. 1, part 1, pp. 5-8.

Hepworth, J.V. and Stride, A. H. 1950. A sequence from the Old Red Sandstone to Lower Carboniferous, near Burrington, Somerset. Proceedings of the Bristol Nat. Society, vol. 28, pp. 135-138.

Kellaway, G.A. and Welch, F.B.A. 1949 British Regional Geology, Bristol and Gloucester District. Old Edition - 1948. (this is the Second Edition, after Welch and Crookall). London, Her Majesty's Stationery Office. Geological Survey and Museum.

Mullan, G.J. and Wilson, L.J. 2005. A possible Mesolithic engraving in Aveline's Hole, Burrington Coombe, North Somerset. Proceedings of the University of Bristol Spelaeological Society, vol. 23, part 2, pp. 75-85.

Reynolds, S.H. and Vaughan, A. 1911. Faunal and lithological Sequence in the Carboniferous Limestone of Burrington Coombe (Somerset). Quarterly Journal of the Geological Society, vol. vol. 67, pp. 342-942. [Example extract] "The magnificent section of Burrington Combe, first studied by Prof. C. Lloyd Morgan, was described in considerable detail in 1905 by T. F. Sibly. This author laid down, as accurately as was possible at the time of his publication, the broad zonal sequence of the faunas. The very large amount of research that, during the last six years, has been devoted to the Carboniferous Limestone Series, both in the British Isles and in Belgium, has demonstrated the importance of more detailed lithological investigations and the possibility of tracing the evolution and migration of the great Carboniferous ---- of Corals and Brachiopods. The series of views illustrate the whole sequence, and are labelled with zonal and faunal indices; the precise points at which important rock-types occur are also marked upon them by means of numerals. II. Description of the Important Rock-Types, arranged Zonally and Lithologically. (S. H. R.). [The traverse is from north to south, the zones being thus encountered in descending order.]
Visean. Lower Dibunophyllum Zone (D1). Extent. The top of Quarry 1 and the hillside on the north. Thickness. A thickness of about 20 feet is exposed in the quarry, and perhaps 80 feet beyond it. The D beds exposed consist entirely of fine-grained and crystalline grey limestone. The red coloration, which is as a rule......."

Smith, D.I. (compiler and editor), assisted by D.P. Drew. 1975. Limestones and Caves of the Mendip Hills. Newton Abbot, David and Charles, for The British Cave Association. 424pp, with monochrome photographs of small size. (The Limestones and Caves of Britain - series).
The first part of this book is interesting, but relatively general. Later parts are moe detailed. Chapter 4 is on "The Erosion of Limestones on Mendip. Chapter 5 on "The Limestone Hydrology of the Mendip Hills has informative detail. Chapter 6, "The Caves of Mendip", by D.P.Drew discusses various theories of cave origin including phreatic origins (see p. 216 for discussion of phreatic loops by D.C. Ford). A classification of Mendip caves, after Gilbert (1960), is given on p. 217. Triassic and pre-Triassic karstification is discussed on p. 218. See pp. 228-232 and Fig 56 for a plan survey of the phreatic cave system of Goatchurch Cavern, Burrington Combe (including "The Drainpipe"). Aveline's Hole, a fossil rising is discussed. There is more Burrington discussion up to p. 234, where it is followed by discussion of the Cheddar catchment. There is much more on the biology of the Mendip caves; cave archaeology and palaeontology etc. From p. 404 et seq. there is a useful bibliography.

Tratman, E.K. 1963. The hydrology of the Burrington area, Somerset. Proceedings of the University of Bristol Spelaeological Society.

Tratman, E.K. Aveline's Hole pp. 369-373 in: Smith, D.I. Limestones and Caves of the Mendip Hills. Newton Abbot, David and Charles, 424pp.

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Copyright © 2019 Ian West, Tonya Loades and Joanna Bentley. All rights reserved. This is a private, academic website intended to be useful for research, reference and educational purposes. Images and text may not be copied for publication or for use on other websites, without permission, or for any commercial activity. A reasonable number of images and some text may be used for non-commercial, non-charged, non-online and non-published academic purposes, including field trip handouts, student projects, dissertations etc, providing the source is acknowledged. All images so used must contain the original caption, including the copyright statement. Some images are not those of the author and the copyright is that of the original photographer and these are not for any use without specific permission from the source photographer. This particularly applies to aerial photographs, but also to some sets of field photographs.

Disclaimer: Geological fieldwork involves some level of risk, which can be reduced by knowledge, experience and appropriate safety precautions. Persons undertaking field work should assess the risk, as far as possible, in accordance with weather, conditions on the day and the type of persons involved. In providing field guides on the Internet no person is advised here to undertake geological field work in any way that might involve them in unreasonable risk from cliffs, ledges, rocks, sea or other causes. Not all places need be visited and the descriptions and photographs here can be used as an alternative to visiting. Individuals and leaders should take appropriate safety precautions, and in bad conditions be prepared to cancell part or all of the field trip if necessary. Permission should be sought for entry into private land and no damage should take place. Attention should be paid to weather warnings, local warnings and danger signs. No liability for death, injury, damage to, or loss of property in connection with a field trip is accepted by providing these websites of geological information. Discussion of geological and geomorphological features, coast erosion, coastal retreat, storm surges etc are given here for academic and educational purposes only. They are not intended for assessment of risk to property or to life. No liability is accepted if this website is used beyond its academic purposes, particularly with regard to matters of risk to life or property.
Some caves of the Mendip Hills are discussed briefly in this webpage but nothing here is intended as any recommendation to enter a cave and no serious guidance to exploring any cave is given here; refer to speleological specialists and/or use speleological literature and maps.

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