P-forms from the Isle of Mull

Abstract

Synopsis Large numbers of well preserved p-forms occur along the southern shore of Loch na Keal on the Isle of Mull. The main forms are curved and sinuous channels up to 20 m long, 3 m wide and 1.5 m deep, but bowls, sichelwannen and other forms are also present. Field measurement of the orientation of 142 channels shows that they are consistently orientated parallel to the direction of ice movement as indicated by striae, and striae are present on the floors and sides of many of the channels. The mode of origin of the p-forms is discussed and it is concluded that meltwater erosion by corrasion and/or cavitation is the most likely process with active ice later moving through them. It may be significant that the p-forms occur along the former boundary zone between mainland and Mull ice.