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 Dorking drains an area of , of which approximately 60% is on Wealden Clay or Atherfield Clay, 20% is on Tunbridge Wells Sand and 20% is on greensand. Brickearth deposits are common in the valley around Betchworth and east of Dorking. The upper Mole catchment is dominated by a single broad terrace, which runs continuously from the entry to the Mole Gap as far south as Tilgate Forest. Above Meath Green (near Horley), the terrace corresponds to the flood plain of the river, however from this point downstream to Brockham, the river cuts a narrow trench no more than wide.