High-resolution reconstruction of the last ice sheet in NW Scotland

• Main Authors: Ballantyne, Colin Kerr, McCarroll, D, Nesje, A, Dahl, SO, Stone, SO, Fifield, LK
• Format: Article in Journal/Newspaper
• Language: English
• Published: 1998
• Subjects: CONTINENTAL-SHELF WEST; DEVENSIAN GLACIATION; NORTHWEST SCOTLAND; FORMER NUNATAKS; OUTER HEBRIDES; ALTITUDE; SOILS; Ice cap; Ice Sheet
• Online Access: https://research-portal.st-andrews.ac.uk/en/researchoutput/highresolution-reconstruction-of-the-last-ice-sheet-in-nw-scotland(57a9dcfe-559c-47cd-9b8b-9396ab61caa4).html; http://www.scopus.com/inward/record.url?scp=0032448615&partnerID=8YFLogxK

Reconstructions of the last (late Devensian) British ice sheet have hitherto been based on assumptions regarding its extent and form. Here we employ observational evidence for the maximum altitude of glacial erosion (trimlines) on mountains that protruded through the ice (palaeonunataks) to reconstruct the form of the ice sheet over approximate to 10 000 km(2) of NW Scotland, Contrasts in the clay mineralogy of soils and exposure ages of rock surfaces above and below these trimlines confirm that they represent the upper limit of late Devensian glacial erosion. The reconstruction yields realistic values of basal shear stress and is consistent with independent evidence of ice movement directions. The ice sheet reached approximate to 950 m altitude over the present N-S watershed, descended northwards and north-westwards, was deflected around an ice dome on Skye and an independent Outer Hebrides ice cap, and probably extended across the adjacent shelf on a bed of deforming sediments.