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

Abstract

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 Mkm 2 ) and volume (~24 m Sea Level Equivalent) at c. 21 ka. Our continentalscale 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;

Middle to Late Devensian glaciation of north‐east Scotland: implications for the north‐eastern quadrant of the last British–Irish ice sheet

“…However, doubts surround the published geochronometry and it is difficult to explain why early deglaciation of the central NSB occurred during a period including the global LGM when other sectors of the BIIS were expanding Sejrup et al, 2016). It is generally agreed that the northern sector of the last BIIS built up towards the end of MIS 3, after c. 32k a BP, when ice extended to the continental shelf margin (Stoker and Holmes, 1991;Whittington and Hall, 2002;Wilson et al, 2002;Bradwell et al, 2008;Jacobi et al, 2009;Chiverrell and Thomas, 2010;Gibbard and Clark, 2011;Graham et al, 2011;Clark et al, 2012;Everest et al, 2013;Hughes et al, 2014Hughes et al, , 2016Hiemstra et al, 2015;Bradwell and Stoker, 2015a). It is unlikely that ice-free areas existed anywhere in northern Scotland during the global LGM, when the BIIS was thick (Ballantyne, 2010;Fabel et al, 2012) (Figure 2).…”

“…Radiocarbon dates on marine bivalves provide ages of 17,652 ± 250 cal a BP (Hall and Jarvis, 1989;Hughes et al, 2016) and 17,490 ± 101 and 18,147 ± 232 cal a BP (Peacock, 1999;Hughes et al, 2016), adjusted using a marine reservoir age of 400a. These dates have been questioned as being too young by Peacock et al (2007) on the grounds that the shells were possibly chalky, but this is incorrect as they retained their original sheen.…”

“…The age of the EO may be estimated from the presence of glaciomarine muds of the Spynie Clay Formation (SCF), which underlies kettled, raised marine flats up to about 20 m OD between Elgin and Lossiemouth (Peacock et al, 1968;Peacock, 1999;Merritt et al, 2003). The muddy SCF has a low-diversity, high-arctic fauna similar to that in the Errol Clay Formation of eastern Scotland, which has yielded radiocarbon ages between 12.8 and 14.3k 14 C a BP (c. 14-16k cal.BP) (Peacock, 1999;Hughes et al, 2016)). The SCF includes large dropstones and lenses of diamict indicating the presence of an ice front nearby (Peacock, 1999).…”

“…We attempt to integrate the lithostratigraphical record with the subglacial bedforms mapped by Hughes et al (2010) and ice-flow patterns (flowsets) interpreted from that record . Of particular interest are the events that occurred during build-up phases of glaciation, which have left little geomorphological footprint and are least well resolved in current reconstructions of the north-east sector of the last BIIS (Bradwell et al, 2008;Scourse et al, 2009;Clark et al, 2012;Hughes et al, 2014Hughes et al, , 2016. Recalculated published dates are taken from a database of geochronometric information for the British Isles (Hughes et al, 2011.…”

Settlements and Seafaring: Reflections on the Integration of Boats and Settlements Among Marine Foragers in Early Mesolithic Norway and the Yámana of Tierra del Fuego

“…18,000 cal. BP (Hughes et al 2016; Van de Noort 2011:4). This marine regime was similar to modern North Atlantic Arctic waters (i.e., very different from the Holocene marine regime in coastal Scandinavia).…”