Sutton and Mole Valley lines Sutton and Mole Valley lines The Sutton and Mole Valley lines were constructed between 1847 and 1868 by the London, Brighton and South Coast Railway, the London and South Western Railway and the LBSCR-sponsored Horsham, Dorking and Leatherhead Railway. Services include commuter services in South London, Surrey and West Sussex operated by Southern, usually from London Victoria to Horsham via Sutton and Dorking. Some Southern services in peak hours from call at and diverge at Leatherhead and serve Effingham Junction and Guildford via the New Guildford Line. The South Western Railway services are operated by Class 455/7s, 455/8s and 455/9s.
River Mole the Pipp Brook, a tributary draining the northeastern slopes of Leith Hill. Between Dorking and Leatherhead the Mole cuts a steep-sided valley (the Mole Gap) though the North Downs, carving a river cliff on the western flank of Box Hill and a smaller cliff at Ham Bank in Norbury Park. The sudden change from impermeable Wealden Clay to permeable chalk and the increased gradient of the river (which drops in the stretch between Brockham and Leatherhead, compared to in between Horley and Brockham) allow the water table to drop below the bed of the river. Water is able to flow