Glacial sediment and landform record offshore NW Scotland: A fjord-shelf-slope transect through a Late Quaternary mid-latitude ice-stream system

Abstract

First paragraph: Current estimates of ice-mass loss from ice sheets vary, but there is consensus that the rate of loss has increased over the last two decades fromc.100 toc.400 Gt a−1with the great majority occurring within ice-stream systems (e.g.Shepherdet al.2012;Hannaet al.2013). Where ice streams terminate in open-marine settings large volumes of ice are discharged into the oceans via calving, as currently seen in Pine Island Bay, West Antarctica or at Jakobshavn Isbrae, West Greenland. At the Last Glacial Maximum (LGM), an ice sheet covered more than two-thirds of the British Isles (50–61° N) and reached onto the continental shelf, in places extending to the shelf edge in the west (Gibbard & Clark 2011;Clarket al.2012). In this contribution we summarize the Pleistocene sediment and landform record of a large mid-latitude ice stream that once drained the NW sector of the British–Irish Ice Sheet (BIIS). Drawing on marine geophysical and geological data from the NW UK continental shelf collected over four decades, we describe the main elements of the system along a transect stretching for >300 km from the heads of the fjords to beyond the shelf slope. The work draws largely on previously published research (Stokeret al.1993,2006,2009,2010;Stoker & Bradwell 2005;Bradwellet al.2007,2008a,b;Bradwell & Stoker 2015a,b), but includes some new insights and interpretations.