Sutton and Mole Valley lines via Epsom and Dorking (including the Bookham Branch) is known to commuters as the "Mole Valley Line" – seven out of the 15 stations are in the Surrey district of Mole Valley. The full title "Sutton and Mole Valley Lines" is used for the lines north of Epsom via Sutton. Confusingly, all Southern services that terminate or call at Sutton are branded as "Sutton and Mole Valley Line" services. The lines which form the route include (in order of construction): None of the lines leads directly to a London terminus, but services use the South Western Main Line to access
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