Cheddar Complex the Pleistocene period. Cheddar Caves contain both active and fossil systems. The active cave system is one of the most heavily studied karst systems in Britain with reference to the conduit and diffuse flow characteristics of its hydrology. Charterhouse Caves include four major swallet caves that provide an indisputable record of Pleistocene landform development in the Mendips and surrounding area. Sun Hole Cave provides a varied fauna radiocarbon-dated to the end of the Late Devensian Cold Stage. Several types of limestone including Clifton Down Limestone, Cheddar Limestone and Cheddar Oolite are visible in the Gorge and surrounding areas with pale
Wookey Hole Caves of , setting a new British Isles depth record for cave diving. This record was broken in 2008 by Polish explorer Artur Kozłowski on a dive in Pollatoomary in Ireland. During 1996–1997 water samples were collected at various points throughout the caves and showed different chemical compositions. Results showed that the location of the "Unknown Junction", from where water flows to the static sump in the 22nd chamber by a different route from the majority of the River Axe, is upstream of the sump in the 25th. There are old legends of a "witch of Wookey Hole", which are still