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The Late Devensian glaciation along the western margin of the Cheshire‐Shroshire Iowland
Author(s) -
Thomas Geoffrey S. P.
Publication year - 1989
Publication title -
journal of quaternary science
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.142
H-Index - 94
eISSN - 1099-1417
pISSN - 0267-8179
DOI - 10.1002/jqs.3390040207
Subject(s) - geology , outwash plain , moraine , ice sheet , geomorphology , drumlin , glacial period , paleontology , sedimentary rock , ice stream , cryosphere , oceanography , sea ice
The glacial succession in the western part of the Cheshire‐Shropshire lowland records the advance, coalescence and subsequent uncoupling of Irish Sea and Welsh ice‐sheets during the Late Devensian stage. During advance a discontinuous sheet of basal till was emplaced across the floor of the region by subglacial lodgement. On retreat, compression of the Irish Sea ice sheet against bedrock obstruction generated a zone of supraglacial sedimentation resulting in the creation of the Wrexham‐Ellesmere‐Wem‐Whitchurch moraine system, and the formation of a wide range of sedimentary environments, including ice‐marginal sandur troughs, ice‐front alluvial fans, proglacial ribbon sandur, and subglacial, ice‐contact and proglacial lakes. The geometry of sedimentary units, and their lithologic and geomorphic characteristics, display spatially ordered patterns of sediment‐landform assemblage which show that the statigraphic succession is a response to rapidly changing depositional conditions at a retreating supraglacial ice‐margin punctuated by minor still‐stands and ice‐front oscillations.