Editing Downland (section)

==Soil==
The [[soil profile]] of chalk downland in England is a thin soil overlaying the [[parent material|parent]] [[chalk]].  Weathering of the chalk has created a characteristic soil known as [[rendzina]].<ref name="SDNPA">{{cite web |last=South Downs National Park Authority |date=2020 |title=Down to earth – the unique soil of the South Downs National Park |url=https://www.southdowns.gov.uk/world-soil-day/ |access-date=10 October 2020}}</ref> Unlike many soils in which there are easily distinguished layers or [[soil horizon]]s, a chalk rendzina soil consists of only a shallow dark [[humus]] rich surface layer which grades through a lighter brown hillwash containing small pellets of chalk, to the white of the chalk itself.  This is largely because of the purity of the chalk, which is about 98% [[calcium carbonate]], and the consequent absence of soil-building [[clay]] minerals which are abundant, for example, in valley floors.

Steep slopes on chalk downland develop a ribbed pattern of grass covered horizontal steps a foot or two high. Although subsequently emphasised by cattle and sheep walking along them, these [[terracettes]] (commonly known as sheep tracks) were formed by the movement of soil downhill, a process known as [[soil creep]].