The course of the river through Norbury Park was partially straightened when the Epsom to Horsham railway was built in 1837, with the removal of a small meander north of Westhumble.Shepperd R (1982) The Manor of Wistomble in the Parish of Mickleham Westhumble Association The meander was reinstated in 1997, in an attempt to enhance this area of the Park, although it has since become blocked by silt. The entirety of the Mole Gap lies within the Surrey Hills Area of Outstanding Natural Beauty.
