Glaciation and deglaciation age of the Stump Cross area, Yorkshire Dales, northern England, determined by terrestrial cosmogenic nuclide (10Be) dating

摘要

Terrestrial cosmogenic nuclide (~(10)Be) surface-exposure ages are reported for three glacially-transported gritstone boulders and one glacially-scoured exposure of gritstone bedrock in the vicinity of Stump Cross Caverns, North Yorkshire. Although the ages do not form a statistically consistent cluster, three of them nevertheless indicate that the transport and deposition of boulders was by ice of the last (Late Devensian) glaciation. The ages provide evidence for glacier ice at the Wharfe-Nidd interfluve, in contrast to previously held views that these uplands had remained above the level of the last ice sheet. The youngest of the three ages on boulders (~18.5 ka) is taken as the best estimate for deglaciation of the area. This is consistent both with surface-exposure ages from sites elsewhere around the southern margin of the Yorkshire Dales and with uranium-series dated speleothems in Stump Cross Caverns. Together these results reveal that deglaciation of the Dales was most likely well advanced by -18-16 ka, facilitating the rejuvenation of surface and subsurface karstic processes.