Furrows under blown sand at Filsö

  Turned furrows in the northern ridge as seen from the west (11th. century AD). A layer of raw humus showing some stratification covers the ridge, and the layer of shifting sand on top of it has traces from the old surfaces. The circular markings in the layer of windblown sand were probably created by oak roots, in which case they were originally of dark colour. - Photo: Vagn Wonsbek.
For further detail, see Vejbaek, O., "Agre og miler ved Filsö", Kuml, 2005, pp. 187-124.