by John Heathoote
Regrettably, the caving potential of Shropshire is rather limited, but before you turn to the next article note that there are a number of underground trips available without resorting to sewers. This article will indicate what there is and where it is. Full descriptions can be found in the references cited, which cover the explorations of the Shropshire Caving and Mining Club over the last 20 years.
Shropshire abounds in limestone, so that the working of it has been an important industry since the 13th century. Limestones of every geological period from the Precambrian to the Carboniferous are present.
Limestone nodules occur in the Precambrian Stretton Shales which make up the eastern edge of the Long Mynd near Church Stretton (SO 4593). They seldom attain sizes greater than 0.5m so the speleological potential is zero! Much the same can be said about the Cambrian Comeley Limestone, 2m thick, and the Ordovician Alternata Limestone, 60m of shale with nodular limestones.
The Silurian limestones - the Wenlock and the Aymestry - are each about 30m thick and the former is of considerable commercial importance as a source of high purity limestone. Both show typical karst features, particularly springs and joint orientated dry valleys. Unfortunately there is only one cave in the Aymestry Limestone at Leintwardine. The reasons for the lack of caves are fairly obvious: both limestones occur as linear escarpments so the flow paths available are very short (less than 400m) and since the limestones form the high ground, no concentration of drainage takes place to produce an enterable cave. In addition, the limestones are either flaggy and so too weak to contain sizeable voids, or are massive and unjointed and thus completely impermeable to water.
Limestones occur at intervals in the Old Red Sandstone sequence of the Clee Hills (50 58) but the thickest, the Psammosteus Limestone, seldom attains a thickness greater than 3m. Many springs are present but that is all.
The main cave development takes place in Carboniferous limestones, as is usual in the British Isles. There are two such sequences in Shropshire, the Spirorbis Limestone in the Upper Coal Measures, and a sequence in the lower Carboniferous, analogous to the Great Scar Limestone of Yorkshire. Only this latter limestone is of any importance to the caver. The lower Carboniferous limestones occur in three parts of the county; on the slopes of Titterstone Glee Hill (SO 67), at Steeraway and Lilleshall near Telford (SJ 71), and around Oswestry (SJ 2929).
The rock of Clee Hill consists of up to 45m of massive and oolitic grey limestone. A number of swallets in the area have been described by Price (1971), including a cave system with a sink to resurgence distance of around 1.6 km and a fall of 45m. The main sink for the system is at FOXHOLES (SO 641803) where a stream disappears under a low cliff. Unfortunately the passage is blocked by a boulder choke and flood debris after a few yards. A shaft sunk near the entrance choke has now collapsed. The resurgence at SO 657803 is totally unenterable - the water issues from fissures in steeply dipping limestone. The stream passage was entered by an incline at SD 656804, driven by the late Duncan Glasfurd, from which it could be explored for about 45m upstream to a sump pool. The Birmingham Enterprise Club attempted to blast a way round the sump, but without success. The entrance now appears to be blocked.
The limestones around Telford offer little scope for cave development. Those at Steeraway are mainly shaly and though there are many springs nothing is enterable. The limestones at Lilleshall are below the water table. Both outcrops of limestone have been heavily mined.
The limestones around Oswestry are the southern tip of the extensive area of limestone that forms the eastern flanks of the Vale of Clwyd, which contains the well known caves Ogof Hesp Alyn and Ogof Dydd Byraf. These are definitely in Wales and so outside the scope of this account. The main cave in the Shropshire part is OGOF CEIRIOG at SJ 265376. This is situated at the foot of a cliff forming the south bank of the Afon Ceiriog, approximately 300m east of a bridge. Ihe large entrance leads via a small passage into a series of rift chambers with abundant debris. The further reaches of the cave are a maze of narrow passages, quite sporting in places. They eventually end in clay chokes. The lower levels of the cave are wet and muddy. Formations are few and unfortunately no longer active. The total explorable length is about 150m and the potential for extension seems small though local tradition connects it with Llanymynech Ogof, 16 km away! A survey of the cave is given by Adams (1972).
At this point it seems sensible to mention OGOF CEIRIOG UCHAF (Upper Ceiriog Cave) at SJ 249368 which is in Wales by about 500m. The cave was first described by Balch in 1907 in 'The Netherworld of Mendip' (!). It was subsequently covered by a landslip and remained lost until 1961, and was eventually reopened by the Shropshire Mining Club in 1962 (Adams 1972). A tight squeeze down a mud slope led to a water worn passage 2.5m wide and 1.5m high. Numerous stalactites 5cm long were present, as well as stalagmites and helictites. It ended in a low bedding plane with a mud floor after 52m. Before this obstruction could be dug the landowner filled the entrance in. Local gossip relates a "dye test" (with a large quantity of sour milk) which proved a conection with Bron-y-Garth, 1.5km to the east and nearly 200m lower, so there is considerable potential.
The rest of the limestone area was thoroughly searched by Adams without finding any enterable cave.
Mining in Shropshire was a long established industry dating from Roman times until 1979 when the last colliery closed. The mines of Shropshire can be divided into three groups: limestone, coal and non-ferrous metals.
The most interesting limestone mine in the area is LINCOLN HILL MINE at Ironbridge (SJ 669038): Unfortunately, while the National Coal Board was capping coal mine shafts in the area in 1978 they capped the limestone shaft but there is a possibility that it may be reopened by the Ironbridge Gorge Museum. According to Brown (1979), the shaft is 33m deep and 2.4m in diameter and is brick lined for the first 15m. The shaft enters impressive pillar and stall workings dipping south east at 30°. The mineral sought was ballstone, masses of almost pure calcite occurring in the Wenlock Limestone. The top of the workings is faulted against Coal Measures, while the lower end continues under water.
Three underground limestone workings can be entered in the vicinity of STEERAWAY. In Engine Wood at SJ 644082 an incline leads down into the Hatch Level, worked until 1918. The level continues down dip for 60m and then goes under water and continues according to local accounts, for another 800m so it could be a diving site. However the roof of the level, which is a crumbly calcareous shale, is very unstable. Masses of coral weighing several tonnes, similar to ballstones in the Wenlock Limestone, are variously suspended in the roof or lying on the floor!
At SJ 654093 is a level driven through the basal sandstone of the Coal Measures towards limestone workings on the top of the hill. It is blocked 20m in, where an air shaft has collapsed. At SJ 653097 a low crawl ending in a squeeze leads into another small limestone working with some muddy gour pools on the floor. Four thin beds of limestone with interbedded shale have been worked for at least 60m, at which point the passage is blocked by a roof fall.
As previously mentioned, the extensive workings at LILLESHALL are 120m beneath the water table, but small workings can be entered, in a quarry known as Jackie Parr's Hole at SJ 732161. The passage is 6m wide by 3m high, sloping at 15° with the south easterly dip of the limestone, diappearing under water after 35m. This was obviously a haulage way for the mine as the winch pulleys were present in 1959 but have since been destroyed (Adams and Hazeley, 1970). Passages can be followed for about 60m north and south of the haulage way before ending in collapse. The mine appears to be the top of a rather irregular pillar and stall working.
Extensive mineworkings are present in the limestones of Llanymynech and Llynclys, near Oswestry. (Though Llanymynech Hill is in Wales, it is on the English side of Offa's dyke and can be considered part of Shropshire). These workings were primarily for lead and copper but appear bo have been largely a late 19th century fraud (Adams, 1972) and little but limestone was ever recovered. Only the Romans at Lianymynech Ogof appear to have had any success (see later). Six levels in the area of LLYNCLYS HILL have been explored and surveyed by the Shropshire Mining Club (Adams 1972). No's 1 and 2 are driven from a quarry at SJ 275226. No. 1 heads SSE and is dry, having a total length of about 80m; no.2 has been driven NNW for 67m and contains a strong stream. This issues from a fissure 12cm by 35cm, which gives an idea of the sort of cave development in the area. Levels 2 and 3 are situated in a quarry at SJ 27322315. They both contain about 60m of passage and No. 4 includes an 8m pitch. A quarry at SJ 27402322 contains levels 5 and 6. No. 5 contains about 640m of passage on three levels. Long drivages predominate and very little stoping was carried out before the working was abandoned in 1910. No. 6 has a locked door, but access can be gained from the quarry above. The working consists of a labyrinth of passages on three levels connected by spiral climbing ways, terminating aganst a vein of clay.
Because of the method by which coal is worked, disused coal workings are usually completely unenterable. Those that remain open are usually filled with gas, predominantly the suffocating and highly explosive methane. Thus the general rule about suspected Coal Measure working is to keep out. Several workings in Shropshire are open but only one can be entered safely. The TAR TUNNEL (SJ 694025) is now part of the Ironbridge Gorge Museun and an entrance fee is charged. The tunnel, which is in sandstone and is brick lined throughout, has been explored for 914m but originally went much further, serving as drainage for at least five coal mines. Public access is limited to the first 100m, which is illuminated. The tunnel takes its name from the natural bitumen (a viscous crude oil) that seeps through the walls and collects in pools. It was a popular tourist attraction in the 18th century and was even visited by royalty.
In a garden in the Lincoln Hill area of Ironbridge is the adit entrance to the CRAWSTONE MINE, in which the Crawstone Ironstone at the base of the Coal Measure sequence was worked. This can be explored under exceptional conditions, but usually the mine atmosphere consists of a mixture of carbon dioxide and methane with too little oxygen to support life. The mine, which closed about 1850, is probably the only explorable example of working by the longwall, tub-stall method. This method was developed in Shropshire but has spread to be the main method of coal working in Britain (in the form of total extraction longwall). The ironstone is a bed of ferruginous sandstone underlain by a thin coal seam and overlain by a bed of sandstone containing fossils of the giant clubmoss Sigillaria.
The main non-ferrous metals worked in Shropshire were lead, zinc, copper and barytes. Lead, zinc and barytes occur together in the area around Shelve (SO39, SJ30), with one or two copper workings elsewhere, eg. Llanmynech. There are some 50 known mines but only a few have significant underground possibilities. Details of the others can be found in Heathoote (1979).
The largest mine in the Shelve area is the SNAILBEACH MINE (SO 375022) which produced lead, zinc and barytes up until about 1920. It left a subsurface void 500m long and 540m deep and now partly filled with water. There are three ways into the mine, two of which involve vertical shafts over 150m deep. The easiest way in is via Robert's Level, situated above the reservoir away from the main workings. After 50m this leads to a wooden bridge across the main stope and then into subsidiary workings on a branch vein. The drop from the bridge to water is 140m, but it is possible to get off the ladder 79m down into the 40 yard level. This leads to a Carpenter's shop and into Chapel Shaft, 64m above water level. The direct descent of Chapel Shaft, which is wet, is 175m. The 112 yard level at the bottom of Chapel Shaft is open but has not been explored. An alternative way down to it from the 40 yard level is via a winze into the 90 yard level, followed by another winze (take your own belay).
A rather more pleasant deep shaft is RAMSDEN'S SHAFT (128m) at Bog Mine (SJ 256977). This vertical dry shaft leads into the BOAT LEVEL, a 3km long drainage adit whose portal is at SO 358001. The Ramsden's Shaft end of this level has not been fully explored. From the portal end it can be explored in dry weather (there is only 35mm of airspace at the entrance) for about 1 km to a fall from which water issues noisily. Attempts by the Birmingham Enterprise Club to remove the blockage with explosives were not successful.
Further up the hillside above Boat Level are the workings of BURGAM MINE. At the base of the tips in the wood are four levels but only one goes for any distance. Past unsafe timbering at the portal, the level follows a rectangular pattern with some stoping on a poor barytes vein. In the same area is a shaft with a tree growing in the middle which makes a fine belay for the 14m descent. The level at the bottom forks after a short way; the left branch leads into a small and very loose stope, the right branch ends in a massive collapse. Above the spoil tips is another level which ends in a fall after 130m. 90m along, an 18m shaft comes in from the surface, which makes a through trip possible. Traces of the rare mineral pyromorphite can be found in this level.
Two other long drainage levels are present in the ore-field. LEIGH LEVEL portal is situated by the B 4499 road at SO 330036 and passes under the road. This level was driven over 3km but never served any useful purpose. It can be explored for about 1km to the bottom of Blue Barn Shaft which has been used as a rubbish tip, blocking the level at this point. Milne Shaft (160m deep) which leads into the rest of the level, was capped with concrete in 1967. Considerable care must be taken in exploring the Leigh Level as there is little oxygen and lethal amounts of hydrogen sulphide after 300-500m. Take your own air!
The portal of the WOOD LEVEL is in the right bank of the Hope Brook at SJ 337007. It issues a lot of water through a concrete grid affair which is quite unenterable. In any case, the first few shafts of it are blocked. Several of the shafts at the far end are open and are, as yet, unexplored. The most promising shafts, both about 70m to water, are Ladywell Air Shaft, in a forestry plantation at SJ 328994, and Rider Shaft at SJ 324981. Others are Spring Vein Pit, Blue Pit, Old Grit Engine Shaft and Hampson's Shaft.
Some distance away from the main lead mining area is HUGLITH MINE (SJ 405015), worked until 1944 for barytes. Few traces remain of the mine site which is now afforested, but it contains the most extensive explorable workings and a variety of through trips are possible between the four entrances. Badger Level Adit is the easiest way in but is well concealed in the forestry high on the hillside. At the end it divides into two; the left hand passage leads to a 33m pitch into Adit Level, the other passage leads down a 10m pitch into an impressive stope at the far end of which daylight can be seen. This is the bottom of a 45m climb down a very loose rubble slope from a small open stope on the hilltop. The large open stope on the hilltop leads down to Badger Level at the junction of the passages. Several tonnes of rock fell from the wall when an attempt was made to descend this stope, which remains unexplored. Adit Level can be followed for about 500m and contains some features of interest. Near the bottom is a fine nest of blue cave pearls and various mining relics are also present. Winzes in the floor lead to the bottom of the mine but water is encountered after 20-30m. Towards the end of Adit Level is a large hole in the floor. A rubble slope leads down from here to the 75 foot level, along which a boating trip would be possible. Returning to Adit Level, a 36m pitch can be found by following the vein workings up the hill and is probably the easiest entrance to find. Various subsidiary workings elsewhere in Huglith Plantation may also be explored.
Various copper workings are present in the limestones of Llanymynech Hill. The most famous of these is LLANYMYNECH OGOF, which was worked by the Romans and silver coins spanning a range from 30 BC to 161 AD have been found there. The cave-like entrance is located at the foot of a small hill in the middle of Llanymynech Golf Course (SJ 265221). Beyond the spacious entrance chamber is a complex series of small passages, tight and wet in places, totalling about 200m. In the centre of the network is a large chamber into which a 20m shaft from the surface enters. A full description with a survey is given by Adams (1970). Two other workings are present on the hill. The Pit is located about 100m west of the Ogof. A squeeze to the south (which will probably need to be dug) leads into a passage somewhat less than 2m square which can be followed for about 80m, sloping steadily downward but never getting more than about 6m below the surface. The Winze series is entered by a mine level 150m to the north of the Pit. The typical 19th century level goes straight in for about 90m with various barren side pasages before entering the bottom of an irregular vein working, part 19th century but part much older (before explosives). By climbing up it is possible to gain access to about 60m of passage, described by Adams (1970).
It seems appropriate in a caving journal to discuss the additional dangers presented by mine exploration. These are primarily loose rock, timbering of various kinds, and gas. The Shropshire Caving and Mining Club cannot provide full rescue cover for without calling on WMCRO (Birmingham) and SWCRO (Swansea).
The processes that deposit the mineral veins usually attack the surrounding rock, reducing its strength. Mining and subsequent weathering further weaken the rock and it may become very crumbly so that pitons and bolts are seldom safe. Rock near the surface is particularly mobile when frost is melting. Piles of waste rock abound and may be held up by rotten wood or often nothing at all. Dry stone shaft linings were not meant for climbers. Remember, when the miners left a section of the mine they didn't intend to return.
Roof supports are usually rotten so it is unwise to enter timbered sections of a mine. Wooden stemples across a stope were to support the miners, not the roof, so their condition does not matter. However, such stemples may support timber false floors. Since these rotten floors are usually covered by rock they are not obvious from above and are extremely dangerous. The uppermost parts of Huglith Mine have false floors.
Gas arises in old mine workings in various ways. Coal workings may contain pockets of methane which is suffocating and explosive (so no naked lights). Mineworkings with extensive timbering contain a lot of carbon dioxide which collects at floor level unless the mine is well ventilated. The air is unfit to breathe when a flame is extinguished*. Levels driven into black shale often contain no oxygen and flames are extinguished. Such levels often contain hydrogen sulphide as well (rotten egg odour). This gas, which is more poisonous than cyanide, deadens the sense of smell so that one cannot smell a toxic concentration.
*Editor's note: Dr. W. Halliday (in 'American Caves & Caving', 1974, p 76) states that whilst candles are extinguished at about 16% oxygen, a carbide lamp can burn in concentrations as low as 8-10%. Since hypoxia (lack of adequate body oxygen) starts at a concentration of about 15%, Carbide lamps must not be used to test for bad air.
Adams, D.R., 1970. Survey of Llanymynech Ogof,
Roman copper mine. Shropshire Caving and Mining Club Account Number 8
Adams, D.R., 1972. Mines & Caves in the area between Llanymynech & the Dee. Shropshire Caving and Mining Club Account Number 9
Adams, D.R. and Hazeley, J., 1970. Survey of the Church Aston - Lilleshall Mining Area. Shropshire Caving and Mining Club Account Number 7
Baker, E.A. and Balch, H.E., 1907. The Netherworld of Mendip
Brown, I.J., 1979. Mines & Mineral Workings of the Coalbrookdale Coalfield, Shropshire. Shropshire Caving and Mining Club Account Number 11
Heathcote, J.A., 1979. A Survey of the Metal Mines of South West Shropshire. Shropshire Caving and Mining Club Account Number 12
Price, G.L.A., 1971, Progress at the Farlow - Oreton Cave. Trans. Birmingham Enterprise Club 5 pp 67-69