We present a new time-slice reconstruction of the Eurasian ice sheets (British–Irish, Svalbard–Barents–Kara Seas and Scandinavian) documenting the spatial evolution of these interconnected ice sheets every 1000 years from 25 to 10 ka, and at four selected time periods back to 40 ka. The time-slice maps of ice-sheet extent are based on a new Geographical Information System (GIS) database, where we have collected published numerical dates constraining the timing of ice-sheet advance and retreat, and additionally geomorphological and geological evidence contained within the existing literature. We integrate all uncertainty estimates into three ice-margin lines for each time-slice; a most-credible line, derived from our assessment of all available evidence, with bounding maximum and minimum limits allowed by existing data. This approach was motivated by the demands of glaciological, isostatic and climate modelling and to clearly display limitations in knowledge. The timing of advance and retreat were both remarkably spatially variable across the ice-sheet area. According to our compilation the westernmost limit along the British–Irish and Norwegian continental shelf was reached up to 7000 years earlier (at c. 27–26 ka) than the eastern limit on the Russian Plain (at c. 20–19 ka). The Eurasian ice sheet complex as a whole attained its maximum extent (5.5 Mkm2) and volume (~24 m Sea Level Equivalent) at c. 21 ka. Our continental-scale approach highlights instances of conflicting evidence and gaps in the ice-sheet chronology where uncertainties remain large and should be a focus for future research. Largest uncertainties coincide with locations presently below sea level and where contradicting evidence exists. This first version of the database and time-slices (DATED-1) has a census date of 1 January 2013 and both are available to download via the Bjerknes Climate Data Centre and PANGAEA (www.bcdc.no; http://doi.pangaea.de/10.1594/PANGAEA.848117).

The last Eurasian ice sheets - a chronological database and time-slice reconstruction, DATED-1

Pattern and timing of retreat of the last British-Irish Ice Sheet

https://su.diva-portal.org/smash/get/diva2:390270/FULLTEXT01.pdf

Too young or too old: Evaluating cosmogenic exposure dating based on an analysis of compiled boulder exposure ages

Dynamic cycles, ice streams and their impact on the extent, chronology and deglaciation of the British-Irish ice sheet

Deglaciation of the Eurasian ice sheet complex.

/pdf/the-northern-sector-of-the-last-british-ice-sheet-maximum-q1vt2zlgbj.pdf

The northern sector of the last British Ice Sheet: Maximum extent and demise

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 and 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 (ca. 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 (ca. 15-11 ka BP). # Natural Environment Research Council (NERC) copyright 2008. Reproduced with the permission of NERC. Published by John Wiley & Sons, Ltd.

/pdf/ice-caps-existed-throughout-the-lateglacial-interstadial-in-27dbnya81x.pdf

Ice caps existed throughout the Lateglacial Interstadial in northern Scotland

The British-Irish Ice Sheet (BIIS) is predicted to have deglaciated rapidly from ~ 18 ka, in response to rising sea level and temperature, similar forcings experienced by modern polar ice sheets. As the main conduits of ice mass loss, the reaction of ice streams to these forcings is thought to have been central in determining the mode and timing of this deglaciation. However, lack of understanding of ice stream influence on the glaciology and deglaciation of ice sheets limits confidence in ice sheet model predictions.
NW Scotland is an area of the last BIIS predicted to have been dominated by ice stream onset conditions. This thesis presents results from a geomorphological and terrestrial cosmogenic nuclide (TCN) analysis study which resulted in the production of a composite ice-sheet thermal regime map and retreat chronology for the last BIIS in this region.
Mapping and surface exposure dating suggest that the regional glaciology and landscape evolution was dominated by the presence of ice-stream onset zones during Greenland Stadial-2 (GS-2). Mountain top erratics were uplifted and transported to high elevation during GS-2, before 16.5 ka BP. By inference, mountain summits were covered by ice during maximal ice sheet conditions.
The existence of sharp thermo-mechanical contrasts, developed in response to ice streaming, are proposed as the main controls on bedrock erosion and terrestrial sediment deposition. The interpretation of ‘trimlines’ in NW Scotland as englacial thermo-mechanical boundaries, is verified by the identification of ‘rip-offs’, a newly recognised geomorphic feature in the UK, and by quantitative demonstration of the increase in glacial erosion in the vicinity of these boundaries. Geomorphic and TCN data supports a conceptual model of thermal inversion following ice-stream cessation. The first description of ‘till tails’ in the UK provides insight into the glaciological organisation and thermal evolution of the BIIS.
A dated (17.6 ka BP) terrestrial glacial limit on the north Sutherland coast indicates early ice retreat from the shelf and provides a minimum
ii
constraint on ice-stream cessation. This indicates rapid loss of ice extent and volume following shutdown of the Minch palaeo-ice stream. Major ice sheet reorganisation c. 15-16 ka BP is suggested by the correlation of some lateral margin ages with high elevation erratic deposition ages implying significant ice thinning and margin retreat prior to this time. Additionally, thinning of ~300 m is predicted for some areas prior to 14 ka BP.

The impact of the Minch palaeo-ice stream in NW Scotland : constraining glacial erosion and landscape evolution through geomorphology and cosmogenic nuclide analysis

In 2006 the British Geological Survey initiated a new cross-thematic project specifically to examine the palaeo-glaciology of the last British Ice Sheet. The project aims to formalise the research carried out by BGS staff since 2001. In collaboration with colleagues at Glasgow, Edinburgh, Aberystwyth and Exeter universities and UK Research Centres (BAS, SAMS) we have started to constrain the spatial and temporal limits as well as the flow dynamics of the last British Ice Sheet using geological field evidence, radiometric dating and numerical simulations. This poster summarises some of the key findings so far, including: 

•	Identification of palaeo-ice streams within the British Ice Sheet, both onshore and on the continental shelf. These include: The Minch, Moray Firth, Forth-Strathmore, Tweed and Witch Ground palaeo-ice streams. 
•	Reconstruction of lateral and vertical ice-mass extents, in key locations such as the Central Grampian Highlands, the North West Highlands, the Cairngorms and the Southern Uplands.
•	Dating of ice-sheet margins using cosmogenic 10Be in the Cairngorms, Strathspey, Wester Ross, Shetland and the Central Grampian Highlands.
•	Simulations of the dynamical evolution of the last British Ice Sheet with high-resolution numerical modelling.
•	Recognition of complexity within the Lateglacial landscape record.

British Ice Sheet dynamics

Glacial ripping is a newly recognized process sequence in which subglacial erosion is triggered by groundwater overpressure. Investigations in gneiss terrain in lowland Sweden indicate that ripping involves three stages of (i) hydraulic jacking, (ii) rock disruption under subglacial traction, and (iii) glacial transport of rock blocks. Evidence for each stage includes, respectively, dilated fractures with sediment fills, disintegrated roches moutonnees, and boulder spreads. Here, we ask: can glacial ripping also occur in sedimentary rocks, and, if so, what are its effects? The case study area is in hard, thinly bedded, gently dipping Cambrian quartz-arenites at Loch Eriboll, NW Scotland. Field surveys reveal dilated, sediment filled, bedding-parallel fractures, open joints, and brecciated zones, interpreted as markers for pervasive, shallow penetration of the quartz-arenite by water at overpressure. Other features, including disintegrated rock surfaces, boulder spreads, and monomict rubble tills, indicate glacial disruption and short distance subglacial transport. The field results together with cosmogenic isotope ages indicate that glacial ripping operated with high impact close to the former ice margin at Loch Eriboll at 17.6–16.5 ka. Glacial ripping thus can operate effectively in bedded, hard sedimentary rocks, and the accompanying brecciation is significant—if not dominant—in till formation. Candidate markers for glacial ripping are identified in other sedimentary terrains in former glaciated areas of the Northern Hemisphere.

Hannah Mathers

Papers

The northern sector of the last British Ice Sheet: Maximum extent and demise

Ice caps existed throughout the Lateglacial Interstadial in northern Scotland

The impact of the Minch palaeo-ice stream in NW Scotland : constraining glacial erosion and landscape evolution through geomorphology and cosmogenic nuclide analysis

British Ice Sheet dynamics

Glacial ripping in sedimentary rocks: Loch Eriboll, NW Scotland