The Vale of Holmesdale is a comparatively narrow valley lying at the foot of the North Downs in Surrey and Kent, England. Its composition is mainly Gault Clay, although the Lower Chalk area at the foot of the Downs is included in the area. The River Medway, for part of its length, flows along the Vale, as do, further to the east, the headwaters of the River Stour.[1] The name of the vale comes from the Holm Oak (Quercus ilex), a non-indigenous evergreen oak, which was once common in the area.[2][3] The Guildford-Redhill railway line runs along the Vale of Holmesdale between Gomshall and Reigate.