Bedrock megagrooves in Assynt, NW Scotland

Bradwell, Tom. 2005 Bedrock megagrooves in Assynt, NW Scotland. Geomorphology, 65 (3-4). 195-204. 10.1016/j.geomorph.2004.09.002

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Geological mapping in Assynt, NW Scotland, has identified three areas of large-scale, linear, bedrock grooving. These closely spaced, subparallel, megagrooves occur predominantly on Cambrian quartzite, are not structurally controlled, and trend generally in the direction of palaeo-ice flow. On the basis of geomorphological evidence, most notably erosional relationships and s-forms, it is proposed that the megagrooves formed at the base of the last (Main Late Devensian) ice sheet and are chiefly the result of high-energy subglacial meltwater erosion. The unusual concentration of bedrock-cut Nye channels in Assynt indicates the presence of large volumes of meltwater beneath the last ice sheet in this region of NW Scotland. This high discharge of meltwater was probably accompanied by localized fast ice-sheet flow, akin to present-day ice streams. It is suggested that bedrock megagrooves may be the geomorphological signature of ice-stream onset zones.

Item Type: Publication - Article
Digital Object Identifier (DOI): 10.1016/j.geomorph.2004.09.002
Programmes: BGS Programmes > Geology and Landscape Northern
ISSN: 0169-555X
Date made live: 14 Nov 2011 14:39

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