Deil's Dyke, Pict's Dyke or Celt's Dyke in south-west lowland Scotland is a linear earthwork that roughly follows the contours that divide upland pasture from lowland arable land, effectively acting like the head-dykes of medieval and later times although its true purpose has not been settled. The Deil's Dyke, sometimes written as 'dike', is formed from an earthen berm of rounded form that varies from 2.0-4.0m wide and a maximum of 0.7m high sometimes having a stone core. Where a fosse accompanies the bank it is usually an inconsequential 0.5m or so in width on average and around 0.4m deep, more often located on the uphill or outfield side. As a defensive structure the dyke has no obvious military value and its erratic route militates against it being a practical political boundary.