Article by Emma Evans, Senior Geophysicist, ION

Approximately 3 miles east of Bath near the village of Bathford in Somerset is the Nature reserve of Browns Folly. Underneath the nature reserve is Browns Folly Mine, a large complex of tunnels and caverns created by the demand for Bath stone to build the Georgian city. Part of the complex was subsequently used by the MOD as an ammunition depot during World War II. In recent years the tunnels have become popular with cavers and occasional partygoers and are also home to a number of geocaches including an Earthcache – GC4P440 – Below Above – The Treacle Mine.

Visiting the mines is quite an experience. We visited three different sections and accessing the tunnels ranged in difficulty from remembering to duck to crawling through a tunnel reminiscent of The Great Escape. Once inside however the tunnels are roomy and easy to negotiate for the most part with the occasional hands and knees crawl or scramble over discarded stone (deads) or fallen roof slabs.

The mines are nothing less than a particularly evocative museum. Mining equipment remains where it was left and footprints from hobnail boots are clearly visible alongside horseshoe prints in the mud (future Anthropocene ichnofossils perhaps). Writing on the walls shows what appear to be customer orders and also the occasional prayer. Unfortunately many of the old rail tracks have been stolen for scrap metal, at least one entrance has been partly filled in by a local caving club to limit access in an attempt to prevent further vandalism, but some do remain and the deep imprint of rails and sleepers is clearly visible. The older parts of the mine pre date the rails and were the domain of horse drawn mine carts. Deep ruts are evidence of the passage of the heavily laden carts and the small stable with its three hitching points is a sobering reminder of how miserable life must have been for the horses. My children also now have a far better appreciation of my occasional threat to send them down the mines.

Evidence of mining activity is also present in the rock with tool marks visible on walls and ceilings and soot marks extending up above the candle niches. In numerous places there are rope marks on the walls and parts of the wall cut away to allow the passage of mine carts around the corners. There are also a number of apparently finished blocks of stone left abandoned at the sides of the tunnels for unknown reasons.

Mining artefacts are not the only attraction in this subterranean world. Old wooden props host mushrooms which glow eerily in the light of a UV torch. Cave formations (speleothem) are in evidence in the form of cave pearls and gours. In a number of places these formations are marked by a ring of stones to prevent them from being trampled. Bats also live in these tunnels although we didn’t see any on this occasion.

The Earthcache itself is known as The Treacle Mine. This is a nod to an old joke which has been played on the gullible since at least the nineteenth century. It is split into two locations showing two different formations of “Treacle” (calcite and other minerals precipitated from the cave water). At the first location the mineral flows down a vertical wall over decades of graffiti. At the second there are stalactites forming as the water drips down from the roof forming flow deposits on the floor below and the occasional pillar as stalactite meets stalagmite.

Having thoroughly explored the tunnels, finding a total of five geocaches we exited through an impressive cavern known as Clapham Junction for perhaps obvious reasons. The cavern itself was formed by the pillar and room mining technique in which blocks of stone are removed but wide pillars are left behind to hold the roof up. The overall effect is of a mediaeval vault on a staggering scale.

The mines are a fascinating place to visit but can be dangerous due to the two main risks of roof fall and getting lost. Go with a guide if you possibly can, maps are also available. Take at least two torches preferably at least one head torch to leave your hands free and wear a hard hat. You will bang your head. Full access conditions and equipment recommendations are available at GC4JEK6 – Below Above – A Tour in Brown’s.