Wookey Hole Caves then passes through major cave systems such as Swildon's Hole, Eastwater Cavern and St Cuthbert's Swallet, around Priddy, but 95% is water that has percolated directly into the limestone. The southern slopes of the Mendip Hills largely follow the flanks of an anticline, a fold in the rock that is convex upwards and has its oldest beds at its core. On the Mendips the crest of the anticline is truncated by erosion, forming a plateau. The rock strata here dip 10–15 degrees to the southwest. The outer slopes are mainly of Carboniferous Limestone, with Devonian age Old Red Sandstone exposed
Wookey Hole Caves SSSI designation, which would restrict what farmers and other landowners were allowed to do, would cover the entire catchment area. This was opposed as being too restrictive and difficult to enforce. It was argued that agricultural uses of fields which were not directly in contact with cave entrances would have little detrimental effect on the caves themselves. There was also debate about which caves and cave features should be considered "important". The final settlement resulted in a smaller area being designated and many agricultural practices being removed from the list of proscribed "Potentially Damaging Operations". The entrance weir and sluice