Beneath its topsoil it is a ridge of London Clay that is capped on all sides (including as isolated knolls in the north) with remaining natural gravel deposits mixed with some sandy soil, which in the South Thames basin is a material known as the Claygate Beds.
The north has very narrow peaks which allow views of the tall buildings of Central London, but the ridge's eastern slope widely commands unobstructed views over Bromley and Addiscombe to the rises of Chislehurst as well as higher Kent parts of the North Downs.
Fourteen of its access points can be said to give areas of this rise their own 'Hill' or 'Mount' names:- Some of the above slopes are in the catchment of the Effra, which had widespread Victorian housing and commercial use so has been converted into parallel combined and surface water sewers which feed into the Crossness works and tributaries of the tidal Thames respectively.
To the south underlying layers of London Clay and Palaeocene between the ridge and the dip slope of the North Downs, where on the near side is the Graveney which feeds into the River Wandle.
[4] This has led to in particular the Crystal Palace area straddling the boundaries of five London Boroughs; Bromley, Croydon, Lambeth,[5] Southwark and Lewisham.