The Priddy area

Parking is available on Priddy Green and at Stock Hill Forest [ST 549 513].

Priddy [74] [ST 52649 50847] is located in the heart of the Mendip Plateau and is a good base for exploring the central part of the Mendips. Several major cave systems occur here, and the area is very popular with cavers. The village is focused around the green, the site of the famous Priddy Sheep Fair which has been held here every year since 1348. Legend has it that the Priddy Fair will return each year so long as the symbolic thatched hurdle stack remains standing on the village green.

Much of Priddy village is on the Black Rock Limestone, which has been used in many of the buildings and drystone walls in the area. The rocks dip gently to the south here at about 25°. The overlying Burrington Oolite occurs just south of the village, but it is poorly exposed. The Avon Group mudstone outcrops between the village and North Hill [76] [ST 54027 51618]. There are very few exposures, but the outcrop is generally marked by a shallow valley or damp marshy ground.

North-east of Priddy is North Hill, at 305 m, one of the highest points on Mendip. On a clear day, most of central Mendip can be seen from this point. Like Blackdown and Pen Hill, this hill is formed from the more resistant Portishead Formation exposed in the core of the North Hill Pericline, rising above the generally flat Mendip plateau. Fragments of the coarse sandstone can be seen scattered over the summit. The sandstone is drained by surface streams, but these sink underground on reaching the surrounding limestone. The largest  stream sinks into Swildon’s Hole [77] [ST 53117 51305]. At 9.4 km in length, it is the longest cave on Mendip. First descended in 1901, it is also one of the earliest systematically explored caves in Britain.

From the entrance, experienced cavers can follow the stream down to a water-filled section, Sump One, almost under Priddy church. This sump was the location in 1934 for a pioneering diving attempt using a home-made respirator (now on display in the Wells and Mendip Museum). From here the stream turns along the strike through eleven more sumps, passing under Priddy Green. The farthest point yet reached lies 170 m below the Queen Victoria pub, east of Priddy Green. Above the streamway lies a complex series of interconnected passages now abandoned by the stream. The water reappears at Wookey Hole.

To the east are two other swallet caves, Eastwater Swallet is located at the end of a classic small blind valley [78] [ST 53864 50627]. St Cuthbert’s Swallet [79] [ST 54310 50465] is the second longest cave on Mendip at nearly 7 km, and certainly the most complex. Below the entrance, several streams enter a series of chambers and passages, before entering a sump 140 m lower.

The Priddy area was an important lead mining area from Roman times right up to the beginning of the 20th century. The ore, principally galena, was won from veins in the Triassic Dolomitic Conglomerate in what is now Stock Hill Forest [75] [ST 55259 51469]. The Dolomitic Conglomerate infills a deep valley that was cut into the Portishead Formation during Triassic times. Good examples of the red conglomerate can be seen in the dry-stone walls alongside the road between the Miners’ Arms and the Hunters’ Lodge Inn. Numerous closed depressions pock-mark the area. Many of these are pits related to lead mining in the area, but some are natural, and formed where the ground has subsided into dissolution cavities in the limestone-rich conglomerate.

The remains of the lead workings with spoil heaps, pits, leats and reservoirs are still clearly visible in the valley between North Hill [76] [ST 54027 51618] and Stock Hill Forest [75] [ST 55259 51469]. The orefield in this area was divided between two of the four mining ownerships known as ‘liberties’, either side of the parish boundary. The St Cuthbert’s Lead Works (part of the Priddy Minery) operated by the Bishop of Bath and Wells, lies at the southern end of the valley [80] [ST 54532 50490] close to the Priddy to Hunters’ Lodge Inn road. Farther north, the remains of the Waldegrave Lead Works (part of the Chewton Minery) [81] [ST 54601 51116], owned by the Waldegrave Family, can be seen near Waldegrave Pool.

In 1860, the owners of Wookey Hole Paper Mill, concerned about pollution of their water supply, traced the water from St Cuthbert’s Swallet to Wookey Hole using ‘Vanadium Red’ dye, having first had several unsuccessful attempts using chaff and even ink. This provided the basis for a successful lawsuit in 1863 against the St Cuthbert’s Leadworks for polluting the stream. This has since been confirmed by dye tracing, the water flowing to Wookey Hole in about eight hours.

In 1862, five furnaces, employing about 40 men, were erected at the St Cuthbert’s Lead Works to smelt the old lead-rich slag left over from earlier mining. The plant closed in 1869, but reopened in 1875 when it became more profitable to ‘dress’ the slag and sell it to lead smelters in Bristol. The site was bought by Mr Theobold in 1890 but, despite investment by him and a new syndicate in 1897, fluctuations in the price of lead caused the works to shut on several occasions, finally closing in May 1908. The Chewton mines are first mentioned in 1541 though they had probably been in existence before then. The medieval works were never really profitable until Cornish miners, notably Nicholas Ennor, introduced new technology in the mid 18th century and started resmelting the old lead- rich spoil, known locally as ‘slimes’. However, the requirement for water led to disputes with the owners of the neighbouring Priddy Minery. The works were never very successful and, in 1881, the smelter was abandoned and the lead-rich slimes sold to a smelter in Bristol. However, by 1883 this venture failed and the works were finally abandoned.

Much of the remains visible today are the legacy of Victorian miners resmelting the lead-rich waste from previous mining operations. Remnants of the smelting plants, with their distinctive stone flues can be seen.

The Priddy and Chewton Mineries are now a Nature Reserve, known as ‘Priddy Mineries’, managed by the Somerset Wildlife Trust. The biodiversity and habitats of the mineries reflects the past history of lead mining in the area. Valley mire, open water, wetland habitats and lead-rich spoil heaps are all present, and the site supports a very wide range of flora and fauna. Valley mire is a very uncommon habitat in the Mendip Hills and here it is especially important for its rich wetland flora, supporting good populations of all three British newts, many different species of dragonfly, as well as frogs and toads. Common lizard and adder are often seen. Greater tussock sedge, purple moor-grass, bog asphodel, cross-leaved heath, hare’s-tail cotton- grass, which is rare on Mendip, and several species of sphagnum moss occur here.

Bare mining spoil and dams are high in lead and other heavy metals, and this generally deters vegetation growth. The rare alpine penny-cress and spring sandwort, another regionally rare plant that thrives on lead-rich soil, are early pioneers of bare slag, occurring alongside sea campion, which is rare so far inland in Somerset. Elsewhere the loose slag is stabilised by rafts of mosses and lichens, including the diminutive and very rare moss Ditrichum plumbicola, which is restricted to lead mine spoil. Other spoil heaps in the valley bottom have been colonised by a neutral grassland that is moderately diverse. Cowslip, yellow-rattle and lady’s bedstraw can all be found. Lady fern, with its characteristic shuttlecock profile, also occurs, one of only a few species of fern that can tolerate metalliferous soils.

Lead mining also took place north of Priddy, now part of the Yoxter Rifle Range [82] [ST 52770 53192]. The rectilinear pattern of the mineral veins, marked by small pits, can be clearly seen in air photographs, but public access is not permitted on the range.

Figures

(Figure 80) Aerial phototograph of the Priddy area.

(Figure 81) Geological cross-section from Priddy to Stock Hill Forest. West [ST 525 513], East [ST 570 517] Vertical exaggeration x Folding in the Black Rock Limestone, Swildon’s Hole.

(Figure 82) Folding in the Black Rock Limestone, Swildons Hole.

(Figure 83) Map of cave systems, mines and veins.

(Figure 84) St Cuthbert’s Lead Works, in the Priddy Minery, c. 1903. Courtesy John Cornwell collection.

(Figure 85) Waldegrave Pool.