The Mendip Hills are the southernmost outcrop of Carboniferous Limestone in England rising to a height of a little over 300m above OD, forming a dramatic contrast with the low lying Somerset levels. The limestone geology gives rise to a characteristic “karst” landscape of crags and gorges. There are no rivers on the main plateau of the Mendips, but ground water permeating through the rock forms a number of springs at the base of the scarp and these feed into the rivers Yeo, the Lox Yeo, The Cheddar Yeo and the Chew. The outpouring of water from these springs has been a key factor in the development of settlement at the foot of the scarps.
Free draining silty clay loam soils are found on the Limestone on Mendip, which tend to be shallow in depth (Smith 1976: 37). The current appearance of the majority of the survey area is typical of Limestone geology, with large areas under permanent grassland. There are also areas of thinner more alkaline soils derived directly from the limestone extending down the steep slopes. (Soil Survey of England and Wales 1983). Woodland is found on the higher areas.
Further east, dropping down off the plateau, the character of the landscape is one of rolling hills and incised valleys. The overall pattern of settlement appears to have been largely dictated by the local topography and geology, with villages located in valley bottoms, near to areas of free draining soils on the lower slopes. The nature of the landscape means that the villages in the eastern Mendip Hills feel very isolated from each other, despite their relative proximity. This proximity of settlement contrasts with the more widespread distribution seen in the western area of the Limestone plateau, the AONB.
Another contrasting factor in the appearances of east and west Mendip are in the field boundaries. The stone walls which are a noted characteristic of the AONB area disappear towards the less exposed eastern end of the plateau, where hedges are predominant. Stone walls were originally erected on the plateau during the post medieval period to provide a temporary shelter and field boundary while hedges were established. However, exposure to the weather meant that hedges did not survive well in western Mendip, meaning that the temporary walls became a permanent feature of the landscape