A wide range of techniques was used to open up this small cave, 240 m long and 56 m deep, in the course of a dig lasting 9 years. Two sumps were removed, but the main obstacles to progress were massive deposits of mud tailings generated by Roman to 19th century lead working in the Blackmoor valley. The Mendip Hills Mining Company set up a waterfall in the entrance rift and, when the wheel became redundant, disposed of mud tailings into the swallet. Mudflows of mobilised tailings surged down the cave during this period.