Coulsdon is one of the southern towns of Croydon. The area is administered by three local councils, most substantial part falls into Croydon Council area, but Sutton, Reigate and Banstead councils manage parts of it as well. Coulsdon is part of the North Downs area. Hills are formed of Chalk and Flint, the soil is generally dry and is the watershed, which has constituted a natural route way across the Downs for new populations. Around 30 000 people live in Coulsdon and benefit from beautiful green valleys, good road connections to Gatwick airport, Brighton and easy reach of M25. The central area of Coulson has substantial industrial, automotive and distribution services, convenience, standard socialising and niche retail as well as local professions of a typical town in the country.
Smitham Bottom or Valley is at the heart of Coulson. It is the location, where the three dry valleys merge into one. Since 2006 a town centre arc of the A23 road and on Chipstead Valley Road, which terminates halfway along the arc, leading directly to Woodmansterne. The soil is dry, and water was obtained even in 1912 by deep wells here in the chalk. Dry valley in the chalk, Smitham Bottom, has a watercourse below the pool. Until the 16th century it occasionally in times of flood ran here but after this it can break out as far as at the foot of the chalk in Croydon and Beddington.