Ice caps existed throughout the Lateglacial Interstadial in northern Scotland

Abstract

We constrain, in detail, fluctuations of two former ice caps in NW Scotland with multibeam seabed surveys, geomorphological mapping and cosmogenic 10 Be isotope analyses. We map a continuous sequence of 40 recessional moraines stretching from ~10 km offshore to the Wester Ross mountains. Surface-exposure ages from boulders on moraine ridges in Assynt and the Summer Isles region show that substantial, dynamic, ice caps existed in NW Scotland between 13-14 ka BP. We interpret this as strong evidence that large active glaciers probably survived throughout the Lateglacial Interstadial, and that during the Older Dryas period (c.14 ka BP) ice caps in NW Scotland were thicker and considerably more extensive than in the subsequent Younger Dryas Stadial. By inference, we suggest that Lateglacial ice-cap oscillations in Scotland reflect the complex interplay between changing temperature and precipitation regimes during this climatically unstable period (~15-11 ka BP). words

Glacial erosion and bedrock properties in NW Scotland: Abrasion and plucking, hardness and joint spacing

“…The study area was deglaciated at c. 14-13 ka (Bradwell et al, 2008b;Stoker et al, 2009). The study area occurs in the centre of a palaeo-ice stream (Fig.…”

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

“…Stoker et al 1993;Bradwell et al 2008a). It is also shown from the type and pattern of subglacial landfoms that an ice stream occupied the trough of the Minch, with its tributaries channelled along fjords sourced deep in the ice-sheet interior (Fig.…”

“…The largest occur close to the shelf break, in present-day water depths of ~200 m. These long broad sediment ridges are up to 20-30 m high and 2 to 4.5 km wide with low-angle slopes and wide poorly defined crestlines. BGS seismic profiles and singlebeam echosounder bathymetry show the longest ridge, near the shelf break, to be in excess of 50 km (Stoker et al 1993;Bradwell et al 2008a). Further inshore on the mid shelf, two other large sediment ridges of similar size and morphology have been mapped from single-beam and MBES data (Bradwell & Stoker 2015b): one ridge connects the Butt of Lewis to the Sula Sgeir high, and the other extends N then E from the Butt of Lewis almost perpendicular to the axis of the crossshelf trough (Fig.…”

“…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 over 300 km -from the heads of the fjords to beyond the shelf slope. The work draws largely on previously published research (Stoker et al 1993(Stoker et al , 2006(Stoker et al , 2010Stoker & Bradwell 2005;Bradwell et al 2007Bradwell et al , 2008aBradwell & Stoker 2015a, b), but includes some new insights and interpretations.…”

Glacial Geomorphology at Glasgow

“…This is playing a central role in the wider understanding of glacial erosion rates and concepts of landscape preservation beneath ice sheets Stroeven et al, 2006;Li et al, 2008). It is also beginning to deliver a more complete chronology of glaciation in both the immediate region (Golledge et al, 2007;Bradwell et al, 2008) and in ancient and modern glaciated terrains overseas Fink et al, 2006). The mapping tradition has moved on but the Glasgow legacy, because it invested in long-term monitoring, will endure.…”