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
Sutton and Mole Valley lines the landowner, Thomas Grissell, meant that vertical ventillation shafts could not be constructed and the tunnel portals were given lavish architectural treatment. Betchworth Tunnel is south of Dorking. It is long with a maximum gradient of 1 in 80 (1.25 per cent). It runs through the upper greensand of the Deepdene Ridge to the east of the town. Construction difficulties delayed the opening south of Dorking. It collapsed on 27 July 1887, remaining closed for over six months. Sutton and Mole Valley lines The Sutton and Mole Valley lines were constructed between 1847 and 1868 by the London, Brighton and