More on Anglian ice limits

This is an interesting new paper by Philip Hughes and Phil Gibbard, assembling a vast amount of information on ice limits and phases of glaciation around the globe.  It's rather technical, but it's worth quoting because it brings up-to-date the latest thinking on limits in southern and western UK.   The map above summarises some of the findings.  MIS 2 is the Devensian; MIS 6 is the mysterious Wolstonian: and MIS 12 is the Anglian.  The latter is the one we are most concerned about when we consider the likelihood of glacial action in Somerset and Wiltshire.  I know that the level of resolution in this map is not very high, but it holds out the possibility that on three separate occasions (at least) glacier ice could have reached Somerset, and that at least one one occasion it could have reached Wiltshire.  So can we please dump this silly idea that "glacier ice could not possibly have reached Salisbury Plain" ??

That having been asked, I'm not really very happy with some of the details of the lines drawn by Hughes and Gibbard.  The Devensian line in the outer part of the Bristol Channel does not withstand scrutiny.  Some glacier ice, at some stage, must have reached the coast of Cornwall.  But I'm pleased to see that the Wolstonian ice edge, once drawn across mid-Wales, has now been abandoned in favour of a suggestion that Wolstonian ice could have covered the whole of Wales.  

Global glacier dynamics during 100 ka Pleistocene glacial cycles (2018)
Philip D. Hughes, Philip L. Gibbard
Quaternary Research (2018), 1–22
 doi:10.1017/qua.2018.37
Accepted March 17, 2018)

Abstract

Ice volume during the last ten 100 ka glacial cycles was driven by solar radiation flux in the Northern Hemisphere. Early minima in solar radiation combined with critical levels of atmospheric CO2 drove initial glacier expansion. Glacial cycles between Marine Isotope Stage (MIS) 24 and MIS 13, whilst at 100 ka periodicity, were irregular in amplitude, and the shift to the largest amplitude 100 ka glacial cycles occurred after MIS 16. Mountain glaciers in the mid-latitudes and Asia reached their maximum extents early in glacial cycles, then retreated as global climate became increasingly arid. In contrast, larger ice masses close to maritime moisture sources continued to build up and dominated global glacial maxima reflected in marine isotope and sea-level records. The effect of this pattern of glaciation on the state of the global atmosphere is evident in dust records from Antarctic ice cores, where pronounced double peaks in dust flux occur in all of the last eight glacial cycles. Glacier growth is strongly modulated by variations in solar radiation, especially in glacial inceptions. This external control accounts for ~50–60% of ice volume change through glacial cycles. Internal global glacier–climate dynamics account for the rest of the change, which is controlled by the geographic distributions of glaciers.

Quote:

In continental Europe, the Elsterian Stage glaciation was more extensive than during the Saalian Stage (MIS 6) limits in eastern Germany and Poland, although not in western Germany and the Netherlands. In the Balkans, the largest glaciation has been dated to >350 ka by U-series dating of secondary carbonates within moraines, with the latter then correlated with MIS 12 by correlation with long lacustrine sequences in Greece (Hughes et al., 2005, 2006, 2010, 2011). The Elsterian Stage is equivalent to the Anglian and Okian Stages (MIS 12) in the British Isles and Russia, respectively. The Anglian Stage represents the most extensive recorded glaciation in southeastern England, when ice reached as far as London.