A palaeo-reconstruction of Devensian ice-flow phasing in the Vale of York.

Ice provenance and dynamic behaviour between the British-Irish ice sheet has been subject to controversy in recent years. Several studies of clast lithology and glacial morphology have alluded to the inland extension of the North Sea Lobe into northeast England and the Vale of York. However, the extent that the North Sea Lobe extends into the Vale of York, and its dynamic interactions with the Stainmore and Wensleydale ice masses is as yet unknown. This study aims to reconstruct the complex provenance of the Vale of York ice lobe through clast lithological and matrix geochemical analysis. Multivariate statistical methods were applied to the datasets in the form of a PCA and Cluster Analysis, to aid in the correlation of Vale of York tills to BIIS and NSL type sites. Indicator erratics for NSL (Cheviot volcanics and flint), Scottish (greywacke and metasedimentary lithologies), and Lake District (felsic tuff) provenance were found in several tills and were central to tracing till provenance. Major and trace metal, and clast lithological cluster analyses have identified at least two occasions where the NSL and Eden-Stainmore ice converges at Scorton Quarry in the north of the Vale of York. NSL ice has been traced as far south and west as Norton Mills. Deposits to the west (Marfield Quarry and Lightwater Quarry) are dominated by a local Wensleydale ice signature and lack evidence of North Sea ice.