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Facies variation in a Late Pleistocene supraglacial outwash sandur from the Isle of Man
Author(s) -
Thomas G. S. P.,
Connaughton M.,
Dackombe R. V.
Publication year - 1985
Publication title -
geological journal
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.721
H-Index - 54
eISSN - 1099-1034
pISSN - 0072-1050
DOI - 10.1002/gj.3350200302
Subject(s) - outwash plain , geology , facies , geomorphology , overbank , paleontology , structural basin , glacial period
The Orrisdale Outwash Member was deposited during retreat of the Late Devensian Irish Sea ice‐sheet in a series of diachronous marginal sandur formed on an unstable, ice‐cored supraglacial topography. Sedimentation was controlled by dead‐ice ridges running parallel to the ice‐margin but as buried ice melted the topographic constraints diminished and individual sandur systems widened and coalesced. The sediments are characterized by very rapid lateral and yertical facies variation caused by channel migration, abandonment, and adjustment to a rapidly‐changing ice and sediment substrate. Facies assemblages consequently show marked lateral transition from high energy, laterally impersis‐tent, gravel dominated longitudinal bar sequences to extensive, low‐energy overbank flood basin successions.