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
Mendip Hills and subsequent erosion has resulted in a range of surface features including gorges, dry valleys, screes, swallets and others typical of karst landscapes. These are complemented underground by a large number of caves both beneath the plateau and at the base of the southern escarpment. Wookey Hole is one example of the caves of the area. There are also areas of limestone pavement and other karst features. Dissolution of the limestone produced many of the gorges including Cheddar Gorge and Burrington Combe. Springs are a common feature of the eastern part of the hills, a number of which have associated