A Country Full of Holes TREVOR

The scientific naming and understanding of to infer the identity of belemnites as fossils relies on much the same methods of cephalopod molluscs; squid they were, thun- comparative morphology. Having seen the derbolts they are not. teeth of a modern shark, Steno was able cor- rectly to interpret tonguestones as the fossilized teeth of ancient sharks. Comparative morphol- Suggestions for futher reading ogy is, however, more difficult to apply if Bassett, M.G. 1982. ‘Formed Stones’, Folklore changes during fossilization profoundly alter the appearance of the organism (as in the case and Fossils. National Museum of Wales. Geo- of ‘horses heads’ (Fig. 6)), or if close modern logical Series No. 1, 32pp. (an invaluable analogues for the fossil do not exist. The latter source reference). is well illustrated by belemnites. No modern Zammit-Maempel, G. 1989. The Folklore of organisms have skeletons resembling the bul- Maltese Fossils, Papers in Mediterranean So- let-shaped guards of belemnites (Fig. 1) with cial Studies, Issue, 1, 29pp. (a detailed histori- their internal structure of radiating crystals of cal account of fossil myths and beliefs on this calcite. The crucial clue to the nature of Mediterranean island). belemnites was the discovery of the chambered phragmocone, constructed of aragonite and hence less often preserved, which fits into the Paul D. Taylor is head of the Invertebrates and conical alveolus of the guard. The Plants Division in the Department of phragmocone was sufficiently similar to the Palaeontology at The Natural History Museum, chambered shell of the modern squid Spirula London. for the 18th-century scientist Balthasar Erhardt

A country full of holes TREVOR. D. FORD Mining voids exist throughout Britain

n recent years, there have been several inci- (Fig. 2). An articulated lorry had one of its Idents arising from the presence of unstable wheels caught in a collapsed sandstone ‘cavern’ old mine workings in parts of England where beneath a Nottingham street (Fig. 3). A back few residents had any memory of anything ever garden in Cornwall disappeared into an unsus- being mined. As examples, a bus fell into an old pected mine shaft. Several million pounds have chalk mine under a street in Norwich (Fig. 1) been spent filling in old limestone mines in the and part of a housing estate in Bury St West Midlands after a series of collapses, one in Edmunds fell into old chalk-mine workings the middle of a football pitch in Dudley! An-

Fig. 1. Collapse of old chalk mines in Norwich, 1988. (Photo reproduced with permission of Eastern Counties Newspapers.)

Gdjul3.p65 145 12/11/98, 15:02 Fig. 2. (left) Crown holes over old chalk mines in Bury St Edmunds, due to liquefaction of chalk by leaking drains. (Photo: Tony Waltham.)

Fig. 3. (below left) Crown-hole failure of sandstone under a passing lorry. A leaking drain weakened the roof over an old wine cellar in Nottingham. (Photo: Tony Waltham.)

and, in spite of the efforts of National Coal Board geologists, many older workings are uncharted. Some 4000 shafts were plotted during the development of the new city of Telford on top of the Coalbrookdale Coalfield. Less well known are the mines, mainly in the Yorkshire coalfield, which have worked products such as ganister and fireclay for refractory purposes. Other materials worked in some coalfields in- clude building stones, usually quarried but occasionally mined. Also, near Pontefract and Castleford there are several kilometres of mine workings only a few metres beneath the surface from which the basal Permian sands have been extracted for glass-making. Coal mining deep beneath these has increased the possibility of subsidence. Several coalfields have also had ironstone mines, where either shales packed with nodules or bedded ironstones were raised.

Metal mining Britain also has its well-known lead, tin, zinc and copper mining fields which have worked vein deposits in Cornwall and Devon, the Mendip Hills, the Peak District, Shropshire, the North Pennines, the Lake District, Angle- sey and in mid and North Wales. Less well

other incident occurred when a recently com- pleted semi-detached house started to collapse at one end of a housing estate near Pontefract while the builder was still erecting houses at the other end, on top of unsuspected old mine workings! By mines, I mean underground workings. Quarries and opencast pits are another story. A quick tour will perhaps open your eyes to what has been mined in the past and thus to where the dangers of instability are greatest.

Old coal mines The presence of old coal-mine workings is an obvious fact of life in the coalfields, and subsidence is only to be expected during extraction (Fig. 4). Once mining has ceased, subsidence damage may decline, but sometimes it is aggra- vated by water movements in the old workings. Fig. 4. Subsidence of the Crooked House due to coal mining at Himley, All our coalfields are affected to varying extent Staffordshire. (Photo: Tony Waltham.)

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Gdjul3.p65 146 12/11/98, 15:02 known are the gold deposits of Dolgellau and the wolfram mines of Carrock Fell. Most of the minerals occur in fissure veins so that workings are more or less vertical. Estimates of the number of shafts vary, but a figure of 50 000 in the Peak District is a fair estimate and equiva- lent numbers are probably present in the other metal-mining fields. Waste was often stacked on stone or wooden stemples in mined-out veins (Fig. 5). Lines of shafts mark many veins, and occasional collapses leave irregular gashes on hillsides. Prehistoric workings for copper ore have recently been identified on the Great Orme at Llandudno, at Cwmystwyth in central Wales and at Ecton in Staffordshire. Apart from lead and zinc ores, fluorspar and baryte are still being worked in some of the old Pen- nine lead-mining areas. Even the common mineral calcite is still worked from veins in the Peak District for stucco, terrazo and other or- Fig. 6. Crown-hole and even fewer have been surveyed. Ironstone namental purposes. Spectacular collapses have subsidences over old nodules have been worked from shale beds in taken place over quite recent ‘spar’ workings in ironstone workings at several coalfields, particularly in Derbyshire Derbyshire. Holwell near Melton and Coalbrookdale. Secondary iron ores have Mowbray, been mined from replacement deposits in the Leicestershire. (Photo: Tony Waltham.) Carboniferous Limestone flanking the Lake District, the Forest of Dean and at Llanharry near Cardiff. Earthy iron ores have been extracted as ‘raddle’ used for pigments at several localities.

Chalk mines The East Anglian counties and several parts of Southern England have all had chalk mines; but why on earth mine chalk when there are large areas of the Downs entirely composed of chalk and easily accessible? Quite simply, with bulk transport being difficult and costly in ancient times, it was cheaper to raise chalk from below your own estate for use as a fertilizer spread on top of superficial deposits which were deficient in lime. At Bury St Edmunds, Fig. 5. Waste rocks ancient chalk mines beneath a housing estate stacked on stone became unstable when leaking drains softened stemples in an old lead the chalk (Fig. 2). Apart from Norfolk and Suf- mine, Via Gellia, folk, chalk has been mined from the ‘dene Derbyshire. (Photo: T. holes’ of Essex and Kent, from galleries near D.Ford.) Reading, Berkshire, and in Buckinghamshire and Hertfordshire. One chalk mine at Chislehurst in Kent has been opened as a tour- Ironstone mines ist attraction. Some chalk, as at Beer in East Bedded ironstones were worked in the Jurassic Devon, was mined as a building stone. rocks of North Yorkshire, Lincolnshire, Leices- tershire, Northamptonshire and Oxfordshire Gypsum, salt and other evaporites until some 30 years ago. Extensive networks of almost horizontal galleries lie at no great depth Gypsum for making plaster has long been in all these areas and crown-hole collapses are mined from the Triassic strata of Yorkshire, fairly common (Fig. 6). Ironstones of early Nottinghamshire, Leicestershire, Derbyshire Cretaceous age were the basis of an ancient and Staffordshire. Some of these areas have iron-making industry in the Weald of Kent and yielded alabaster for ornamental and tomb- Sussex, but few of the workings are accessible stone use. Recent road construction ran into

Gdjul3.p65 147 12/11/98, 15:03 problems with unsuspected cavities in the gypsum beds south of Derby. There are also extensive gypsum/anhydrite mines at Billingham on Teeside, at Sherburn-in-Elmet, East York- shire, and in the Vale of Eden in Cumbria. Gypsum has also been raised from Lower Cre- taceous strata in the Weald of Sussex. Salt is mined or pumped as brine from the Trias in Cheshire and adjacent parts of North Stafford- shire, often with extensive collapses. Potash salts are raised from the Permian evaporites near Whitby in north-east Yorkshire, but the great depth of the workings has not led to any surface problems as yet.

Building stones Various building stones have been mined too. Sandstones have been exploited underground in several places in the Pennines and in Staf- Fig. 8. A pillar fordshire. Perhaps the best-known building- and others for sand to spread on floors before supporting the roof (?) the days of carpets (Fig. 9). Over 400 of these stone mines are those which worked the in a Hearthstone Mine Inferior Oolite around Bath and Corsham artificial sandstone ‘caves’ have been charted at Godstone, Surrey. by Tony Waltham and others from Trent Uni- (Fig. 7). Slabby calcareous sandstone in the (Photo: Richard Shaw.) Lower Greensand was mined for hearthstones, versity and from the British Geological Survey. doorsteps, lintels and window sills from the Sandstone ‘caves’ used as dwellings also occur Lower Greensand at Godstone in Surrey, in Worcestershire. A system of tunnels was ex- partly beneath the M25 (Fig. 8). At nearby cavated for use as air-raid shelters beneath cen- Merstham, there are similar mines close to the tral Stockport. Extensive tunnels in the Triassic M25/M23 intersection. Vast quantities of grout sandstones beneath part of Liverpool were dug had to be pumped in to secure the foundations out early in the 19th century to relieve unem- of these roads. There are said to be some 25 km ployment. Sand for glass manufacture has been of tunnels in this area. extensively mined near Pontefract and Castle- ford in Yorkshire, in places resulting in networks of galleries less than 5 m below the Sand mines surface. Deteriorating pillars have resulted in houses collapsing in the overlying housing es- It may seem unlikely that anyone would mine Fig. 7. Signs of roof tate, apparently built before planners or devel- sand, but such mines are widespread. Sands and pillar failure in a opers knew there were mine workings so close from the Triassic Sherwood Sandstones were Bath Stone mine, to the surface. Glass sand was also worked at excavated beneath the built-up area of central Corsham, Wiltshire. Reigate in Surrey (Fig. 10). Sand for local Nottingham, some as dwellings, as an under- (Photo: Tony bottle-making was mined at several places in ground tannery, as extended cellars for storage Waltham.) Kent and East Sussex, but often the poor quality meant that the sand could only be used for builders’ mortar. Glass sand has also been mined at the remote Loch Aline in the Scottish Highlands.

Limestone mines In spite of Britain having whole ranges of hills made of limestone, limestones in the Silurian inliers within the coalfield of the West Mid- lands have been extensively mined around Dudley and Walsall, largely for fluxing in iron furnaces (Fig. 11). One series of such ‘caverns’ is open to the public adjacent to the Black Country Museum at Dudley. Tours are by boat along the underground haulage canals. Nearby, several million pounds have had to be spent to stabilize collapsing workings. Within

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Gdjul3.p65 148 12/11/98, 15:03 fordshire and in parts of Derbyshire. The flagstones were used for paving, flooring and roofing slabs and as gravestones.

Slate and pseudo-slates Apart from the vast slate quarries in North Wales, slate has been mined in many parts of Wales both for roofing purposes and for building blocks. Some slate mines around Blaenau Ffestiniog are now tourist attractions. The fis- sile Middle Jurassic limestones of Collyweston in Rutland and Stonesfield in Oxfordshire have been raised for roofing ‘slates’. Little known workings for similar ‘slates’ were at Duston near Northampton.

Jet and oil shale The Jurassic shales near Whitby on the York- the Jurassic Oolites, limestone was raised for Fig. 9. Roof failure shire coast have had tunnels driven into the over a sandstone ‘cave’ building stone around Bath and Corsham in cliffs for jet, once popular for Victorian jewel- Wiltshire. Similar building stone was mined (actually a beer cellar) with debris from the lery. At nearby Ravenscar, shale was mined for from the Portland Beds at the Tilly Whim alum production. Oil shale was once mined ‘Caves’ in the cliffs near near Swanage, whence surface, Nottingham. (Photo: Tony from Upper Jurassic rocks at Kimmeridge on it could be directly loaded into boats. Lime- Waltham.) the Dorset coast. In pre-war days, there was a stones packed with the fossil gastropod flourishing oil-shale mining industry in the Viviparus have been worked from mediaeval Carboniferous rocks of the Lothian area of times almost to the present day in the Isle of Scotland with vast waste heaps or ‘bings’ of Purbeck, under the name of Purbeck Marble. burnt shale. The similar Sussex marble was once mined in the Weald. Kentish Ragstone is an impure sandy limestone which has been mined widely Chert mines for use as a building stone in several areas of Kent. Muddy Hydraulic Limestones of Lower Less well known were mines for chert around Jurassic (Liassic) age near Barrow-on-Soar, Bakewell, in Derbyshire, where several kilome- north of Leicester, were mined for cement tres of galleries are still open, partly beneath manufacture. The uncharted and flooded old Fig. 10. A gallery in a built-up areas. Other chert mines were near workings caused problems when a modern gyp- glass sand mine near Richmond in the Yorkshire Dales and in north- sum mine was developed in the underlying Reigate, Surrey (Photo: east Wales. The chert was extracted in large Trias! Limestones for ornamental and building Richard Shaw.) blocks for use in grinding the china-clay mix- purposes have also been worked around ture in the Potteries. Torquay, near Swanage, in the Weald, and in various parts of the Pennines. There are extensive limestone mines near Holywell in North Wales. Near Wirksworth in Derbyshire, the Middleton Mine has produced high-quality limestone for glass-making and sugar-beet re- fining for the last 40 years. Failure of pillars over unknown cavities resulted in the subsidence of several acres of farmland. Similar mines near Buxton were once used for research into explosions in mines and later as mushroom farms.

Flagstones Apart from extensive quarries, flagstones have been mined from the Millstone Grit around Burnley in Lancashire, near Dent in Cumbria, at Elland in Yorkshire, near Longnor in Staf-

Gdjul3.p65 149 12/11/98, 15:03 Comments and conclusions The above list is undoubtedly incomplete. Workings range from networks of galleries large enough to drive a bus around and several kilometres long down to scratchings barely deep enough to go beyond daylight. All pose problems of possible collapse, particularly if building developments take place directly on top in ignorance of what lies below. House- holders can occasionally claim compensation, whilst knowingly allowing developments to go ahead on top of unstable old mine workings may lead to charges of negligence. In these days of litigation, the Department of the Environment became concerned at the in- crease in claims a few years ago, particularly when they started coming in from areas the DoE did not know to have any mines. The DoE Flint mines Fig. 11. ‘Caves’ in the commissioned a research study* to find out just Wenlock Limestone on how extensive old mine workings were, what Within the chalk, flint nodules were mined in Wrens Nest Hill, had been worked and where, as well as the pos- Norfolk, Suffolk and Sussex in Neolithic times, Dudley. (Photo: T. D. sible environmental dangers. Whether any because the fresh flint was better for chipping Ford.) treatments could be applied was the obvious into shape than weathered flint from the sur- follow-up question, but that is usually a matter face. Much flint was squared into building for planners, civil engineers and builders. Part blocks for use in East Anglian churches, etc., of the study resulted in a national database be- although most of it seems to have been ob- ing set up to collate and record the information. tained from surface quarries. One of the startling results was that no county in England and Wales appeared to be abso- lutely clear of old mine workings for some min- Phosphate nodules eral or other. When one looks at some counties, Small amounts of phosphate nodules were one can only wonder what was worked in such raised in Cambridgeshire and elsewhere for fer- an unlikely geological environment, but, sure tilizer. The extent of underground mining was enough, if one looks hard, something has been very small. mined somewhere. All local authorities should be aware of the problem and should have records in their Plan- Miscellaneous ning Departments so that developers can be warned of potential problem areas where old Scattered, less well known mine workings in- mine workings could occur. In doubtful cases, clude those for secondary copper and lead ores planning officials may demand proof that sites at Alderley Edge in Cheshire and in Shrop- are safe before any proposal is accepted. Only shire. A minor amount of lead ore was mined with careful investigation can problems from near Shepshed in Leicestershire. Small quanti- the past can be avoided. ties of secondary manganese ores were raised in The quantity and reliability of old mine the Peak District for use in pigments. Bedded records is highly variable. Coal-mining records manganese deposits in Cambrian strata were are mostly with the Coal Authority at Bretby, mined around Nuneaton in Warwickshire and near Swadlincote. Other coal-mining records north of Dolgellau for use as metal ores. Fullers have been dispersed to local authorities. Simi- earth was mined from Upper Jurassic strata in *The DoE research larly the non-coal-mine abandonment plans Sussex and near Bath, the absorbent clays be- that used to be with the Mines Record Office ing used in the textile trade. Tar was ‘mined’ study was contracted out to Arup have now been dispersed to county or unitary from a tunnel near Coalport in Shropshire. Geotechnics and the authority Record Offices, with some photocop- Graphite was mined at Seathwaite and formed resultant Review was ies also housed in planning departments. With the basis of the Keswick pencil industry. published in 26 the changes in local authority boundaries, plans Apart from the above productive mines, volumes (with 55 may not always be transferred to the new dis- there are networks of underground aqueducts, maps) in 1991. Details tricts. As some unitary authorities have little in sewers, fortifications, munitions stores, railway are available from Arup the way of archival facilities, their records may and road tunnels, and a variety of underground Geotechnics, Bede still be housed under the old county system. House, All Saints, follies, all adding to the catalogue of holes be- Some clay or ironstone mine plans may be with neath our green and pleasant land. Newcastle upon Tyne NE1 2EB. the Coal Authority depending on whether coal was worked at the same time.

Gdjul3.p65 150 12/11/98, 15:03 Whilst counties with long metal-mining his- archival sources and to update these as devel- tories, such as Cornwall and Derbyshire, have opment progresses. Unfortunately, few plans in good databases, for many of the old mines there Record Offices can be taken as fully accurate are no known surveys and the extent of the representations of what is really there. The workings is uncertain. These are ripe for local Record Offices can be useful sources of infor- geological and historical studies. mation, but the users should always be wary. Apart from the obvious dangers of collaps- There is little doubt that detailed research by ing mine workings, there are other risks. All too historians will uncover far more than was found often, old mines have been used as waste in the DoE research study. dumps, and drainage via old workings can carry The DoE also commissioned a separate pollutants far enough to affect neighbouring study and compilation of a database of natural water supplies. Rising or falling water-tables cavities beneath the surface – i.e. caves – but can introduce other problems; recently flooded that is another story! old workings may mean that overflow springs appear where there were none before, and such springs may cause difficulties with construction Suggestions for further reading projects or even trigger landslides. Falling There are too many local historical accounts to water-tables may remove hydraulic support list them all, but the following are a useful sam- and stimulate collapse. Gas in old mine work- ple: ings is another problem; sometimes mine en- trances have been blocked for safety with no Bick, D. 1985. The Old Copper Mines of thought to the possible accumulation of gas Snowdonia. Newent, Gloucestershire. within, and if methane later leaks out it may catch fire or even explode. Furthermore, old 130pp. mine workings may transmit methane from Bradshaw, J. & others. 1991. Kent and East Sus- nearby rubbish dumps to beneath adjacent sex Underground. Meresborough Books, housing estates. Other old mines may be kept Rainham, Kent. 128pp. open as bat roosts. Ford, T.D. & Rieuwerts, J.H. 1983. Lead Min- Britain is indeed a country full of holes, ing in the Peak. Peak Park, Bakewell. (3rd many resulting from the Industrial Revolution. edition; new edition in preparation.) Any geologist, mining engineer or environmen- Waltham. A.C. 1996. Sandstone Caves of tal scientist employed by a local authority, by a Nottingham. East Midlands Geological Soci- developer or by a consultant company dealing ety, Nottingham. 55pp. in such matters would be well advised to famil- iarize himself with the history of mining in his area. It would also be sensible to assemble a Trevor D. Ford is an Honorary Research Fellow database of maps or plans of the extent of work- in the Department of Geology, University of ings both from field observation and from Leicester.

Topics

Tourism in geological early speakers, allowing that they were addressing quite a representation of local government officers with responsibility for leisure and tourism, it seemed landscapes there was a sad indifference in the public to the rich diversity which our varied geological formations ERIC ROBINSON bring to most regional landscapes. Given the hunger On 23–26 April 1998, the Geological Curators’ in the average urban Briton for the outdoors and the Group and the Geoconservation Commission of the countryside, how could they fail to respond to expla- Geological Society convened a meeting in Belfast to nations as to why it takes the form it does? Several consider ‘Tourism in Geological Landscapes’, a title speakers gave their personal testimonies as to what which was soon contracted to ‘Geotourism’. At the drew them first to geology, each in theory being a heart of this was a hard look at our efforts to use our pathway still there for others to follow, but was this a diverse landscapes to win public attention in the recipe for the public in numbers? Were we being per- ‘right’ way. fectly honest with ourselves, let alone those who were Discussed as a serious topic, it soon emerged as our target? our age-long concern that geology as a science does By the second day, there came the admission in not get the recognition it deserves. Listening to the some of the statements that perhaps we were taking

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