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The Late Devensian glaciation of the eastern Lleyn Peninsula, North Wales: evidence for terrestrial depositional environments
Author(s) -
Thomas Geoffrey S. P.,
Chester David K.,
Crimes Peter
Publication year - 1998
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/(sici)1099-1417(199805/06)13:3<255::aid-jqs353>3.0.co;2-u
Subject(s) - geology , outwash plain , glacial period , moraine , ice sheet , geomorphology , sedimentary depositional environment , paleontology , glacier , interglacial , oceanography , structural basin
The glacial deposits of the eastern Lleyn Peninsula record the advance, coalescence and subsequent retreat and uncoupling of Welsh and Irish Sea ice‐sheets during the Late Devensian cold stage. During advance a thick sheet of basal diamict was deposited over much of the area, and during retreat and uncoupling, which occurred after 14.5 ka, the eastern part of the area was dominated by the formation of a large sandur system draining from the retreating margin of the Irish Sea ice‐sheet. Subsequent stages of retreat are marked by a series of arcuate cross‐valley moraines formed either by ice‐contact deposition during stillstand or by structural deformation during minor snout oscillation. In the western part of the area sedimentation was controlled by a series of dead‐ice ridges running parallel to the retreating ice‐margin and this led to the development of a complex assemblage of localised depositional environments including ice‐front alluvial fans, marginal sandur troughs and pro‐glacial lake basins, all formed under supraglacial ice‐marginal conditions. No evidence of glaciomarine deposition is recorded. © 1998 John Wiley & Sons, Ltd.