Caterham - Geography - Physical Geography - Elevation Soil and Geology

Elevation Soil and Geology

The parish is on the Chalk downs, but they are in great part capped by clay and gravel

Elevations range from 230m Above Ordnance Datum in the southwest extreme, "Whitehill Tower, War Coppice Road in Caterham Valley". to 110m Above Ordnance Datum along the railway track, immediately below Croydon Road roundabout, a tripoint partly in Woldingham, Whyteleafe and Caterham.

Caterham lies within the North Downs and Caterham Valley's southern border is immediately south of the North Downs Way, part of a national trail network, which is here on top of the southern edge of the North Downs.

Soil here has the expected shallow, lime-rich soil over chalk or limestone of the escarpment with lower parts of the escarpment summit here, where the topsoil has eroded, having slightly acid, loamy and clayey soils with impeded drainage, which makes that soil particularly fertile.

The gault clay and the middle chalk that lies under the North Downs are both at their thickest around the valley that occupies the centre of Caterham Valley. While earlier cretaceous clays and greensand and sandy material, underlying, is evident where terrain has eroded, 90 million years ago the North Downs hard chalk was deposited, a white limestone comprising over 95% calcium carbonate. It contains thin beds of marl and nodules of flint, either scattered or in bands. The North Downs extending from Farnham to Dover are formed by this chalk. They now have an often white, almost vertical south-facing slope. In lower slopes flints washed up by early seas come more to the surface and appear closer to the surface.