Source/Archive record SEM8447 - The evolution of the Valley of Rocks, North Devon

The Valley of Rocks is the largest remnant of a dry valley system running parallel to the Bristol Channel coast near Lynton in Devon. Two conflicting ideas have been presented for its origin: marine capture and dissection of a river valley, or as an overflow channel from an ice marginal lake. The uncertainty arises mainly because the erosional form has been obscured by solifluction deposits. To resolve this difficulty a study of the solifluction deposits in the Valley of Rocks, and in another remnant at Lee Abbey, has been made, using an electrical resistivity technique. The results show that the deposits increase in thickness from 27 m at the eastern end of the Valley of Rocks to 35 m at the western end near Wringcliff Bay. Rockhead levels at these positions are 56 m O.D. and 123 m O.D. respectively. At Lee Abbey the deposits are 31 m thick and rockhead is at a height of 78 m O.D. These two remnants thus cannot be part of a single valley and as marine erosion has progressed fairly rapidly, the weight of evidence favours marine dissection of a river system. Only one capture of the major river appears to have occurred at Lynmouth during the Ipswichian, followed by capture of a minor tributary at Lee Bay. Modern erosion has resulted in further and continuing dissection of the valley system.