Calcaerous woodland occurs on thin soils where chalk is close to the surface. These conditions are most often found on the escarpment of the North Downs and on valley slopes, but may also occur on the plateau of the dip slope. Calcaerous woodland is typically dominated by beech, hornbeam, yew and ash. Box Hill has one of the largest areas of native box woodland in England. One notable species characteristic of calcaerous woodland is the nationally scarce lady orchid, which is found in more than 100 sites on the Kent stretch of the North Downs, but is confined to just two sites elsewhere in the UK.