Mendip Hills the hills. The western end of the hills is crossed by the M5 motorway and A38. Further east, and running almost north to south, are the A37 and A39. A wide range of outdoor sports and leisure activities take place in the Mendips, many based on the particular geology of the area. The hills are recognised as a national centre for caving and cave diving, as well as being popular with climbers, hillwalkers and natural historians. Wookey Hole Caves and some of the caves in Cheddar Gorge are open as show caves; however, many of the caves of the Mendip
Wookey Hole Caves as an inlier at the centre. Wookey Hole is a solutional cave mainly formed in the limestone by chemical weathering whereby naturally acidic groundwater dissolves the carbonate rocks, but it is unique in that the first part of the cave is formed in Triassic Dolomitic Conglomerate, a well-cemented fossil limestone scree representing the infill of a Triassic valley. The cave was formed under phreatic conditions i.e. below the local water table, but lowering base levels to which the subterranean drainage was flowing resulted in some passages being abandoned by the river, and there is evidence of a number of abandoned