| Abstract: | The 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. |
