A whole suite of geolgical dykes of Permian age cross-cut the Old Red Sandstone of Orkney. For its part, the Devonian age sandstone shows superb desiccation polygons - the Orcadian depositional basin was an intramontane one, rather than marine, so dried out from time to time.
Uploaded to Geograph by Alan Bowring on 11 August 2011
Photo © Alan Bowring, 11 August 2011. Licensed for reuse under this Creative Commons licence