Subglacial meltwater channels at Thurstaston Hill, Wirral and their significance for Late Devensian ice sheet dynamics

Abstract

Small-scale bedrock features of glacial meltwater erosion such as Nye channels are rare in Britain and these features do not appear to have been previously described from England. In this paper we describe the range of glacial meltwater features developed at Thurstaston Hill, Wirral. The forms at this site are carved in Triassic sandstone and include a spectacular three-dimensional linked plunge pool-Nye channel cavity system. Across the site as a whole, Nye channels are the most common landform. The channels are mostly linear and incised in bedrock to a depth of up to 1 m. These features show two prominent orientations, one parallel to regional ice flow during the last (Late Devensian) glaciation and another transverse to ice flow. There are three important implications for the Late Devensian glaciation of the area: (i) the ice sheet was relatively thin and heavily crevassed at the time when the system was created; (ii) deglaciation was characterized by active ice with no evidence for ice stagnation; and (iii) deglaciation was achieved under warm-based conditions.