• Aside from Hoy, the low, open valleys between ridges and which lie submerged the floor of the sounds are products of ice sheet erosion, with deformation of ice around high ground.

  • Ice flowing from N-S down the valley now occupied by the Rackwick Burn has not only deepened the valley, it has widened it too. The cliffs of Grut Fea and Clicknafea truncate preglacial valley spurs and give way downslope to scree. It is noteworthy that these cliffs occur on the outside of a broad bend in the valley where the moving ice would have been forced against the hill slope.

  • The colour of the tills on Orkney is largely a reflection of the rocks over which the ice had passed. The red marls and sandstones of the Eday Group give a distinctive red till and erratic clasts of red sandstone are a major component of these tills in the eastern parts of Westray. ...