Mole Gap to Reigate Escarpment and there are well developed river cliffs where alluvial fans have diverted the River Mole against the valley sides. Mole Gap to Reigate Escarpment Mole Gap to Reigate Escarpment is a biological and geological Site of Special Scientific Interest west of Reigate in Surrey. It is a Geological Conservation Review site and a Special Area of Conservation. Part of it is a Nature Conservation Review site, Grade I. Two small private nature reserves in the site are managed by the Surrey Wildlife Trust, Dawcombe and Fraser Down. This eight mile long site on the North Downs contains an outstanding range
River Mole fast swimming mayflies and riffle beetles. The beautiful demoiselle ("Calopteryx virgo") disappeared from the River Mole during the 1960s owing to deteriorating water quality, but has since recolonised. The white-legged damselfly ("Platycnemis pennipes") is also found along the river and the downy emerald ("Cordulia aenea") is found between Box Hill and Leatherhead. The Mole is one of only three locations in England where the river shingle beetle ("Meotica anglica") is found. A nationally scarce species which is locally common on the River Mole is the greater dodder ("Cuscuta europaea"). The Mole catchment area includes twelve Sites of Special Scientific Interest