The Late Devensian glaciation along the border of northeast Wales

Abstract

AbstractThe glacigenic succession along the border of northeast Wales records the advance, coalescence and subsequent uncoupling of Welsh and Irish Sea ice‐sheets during the Late Devensian cold stage. During coalescence, extensive basal tills were deposited and considerable diversion of pre‐existing drainage was accomplished by subglacial meltwater. Analysis of borehole data and quarry exposure indicates that a complex assemblage of ice‐contact, proglacial fluviatile and lacustrine environments was developed during uncoupling and subsequent retreat. Neither of the previously proposed models for the formation of the so‐called Wrexham ‘delta‐terrace’ are adequate to explain the wide variety of sedimentary successions observed and the feature is a complex, diachronous structure that reflects rapidly changing depositionai conditions, including ice‐front alluvial fans, sandar and proglacial and ice‐contact lakes, formed at the margin of a retreating ice‐sheet.