The Burrington area of western Mendip is well known for its caves, and contains over 3.7 km of surveyed passage. The typical Burrington cave consists of a maze network of predominantly small phreatic tubes generally aligned along strike and developed at certain preferential elevations, linked by steeply descending vadose canyons. Many of these passages are partially sediment choked. The speleogenesis of these cave systems is governed largely by the geological structure, the rate of erosion of the Mercia Mudstone in the Vale of Wrington and locally modified by sediment influx off the northern slopes of Black Down. Several well-developed former water-tables, analogous to those seen in the caves on the southern side of Black Down can be identified at elevations of 166-160 m, 151 m, 140 m, 127m, 115 m and 106 m AOD. A summary of the hydrology of the Burrington area is given and an estimate of the age of the caves calculated.