The Times Atlas and the Greenland ice edge

Many of us will have followed one of this week's big stories -- about the Times Atlas misrepresenting the extent of ice wastage around the edges of the Greenland ice sheet.  Part of the reason for their misunderstanding seems to be the misapprehension that ice sheets have nice simple edges that move forwards during the waxing phases of glaciations and then move back when a glaciation comes to an end.  So the simple idea is that you can just draw a line on a map, and that's sorted.......

But this is not what happens, except where you have a gently undulating plain under the ice, as in parts of SW Greenland today.  Elsewhere, as the ice thins, the edges of the ice sheet tend to break up into scores or hundreds of smaller ice sheet fragments or ice caps, on plateau surfaces and mountains, while the valleys between them are deglaciated and become green.  Troughs that were under the ice are also exposed -- to become fjords near the coastline.  Look at these pics from Google Earth:

 The top image is of Nordvestfjord near the coast of east Greenland; I defy anybody to draw a line on a map showing where the ice sheet edge is today -- plateau ice caps, glaciated uplands, and outlet glaciers and valley glaciers everywhere.  Many of these ice masses are in a relatively healthy state -- we cannot just assume that they are wasting away at a catastrophic rate.

The lower pic gives a very different impression.  Here in SW Greenland the ice edge is retreating across a deeply scoured lowland, and as the ice thins the edge does indeed retreat in the classical sense. 

So -- generalisations are bound to lead to trouble.......

This pattern of ice sheet growth and ice sheet breakup is very close to what Henry Patten and others are finding in their models for the last (Devensian) glaciation.  If you run Henry's model of the expansion and contraction of the Welsh ice cap you will see a sort of flickering effect, with little ice caps (including one on Preseli) coming and going in step with climatic oscillations, eventually being "gobbled up" by the main ice cap, and then becoming independent and isolated again as the glacial episode draws to a close. 

And the relevance for the South-west of England and Stonehenge?  Well, I am increasingly convinced that there WERE small independent snowfields (and maybe actual glacier ice, frozen to the bed) in the upland areas including the Mendips, Exmoor, Dartmoor and Bodmin.  As the ice thickened in the Bristol Channel and as the Irish Sea Glacier started to move in, these independent areas of ice became incorporated, or coalesced together, to create a very complex area on the "ice sheet periphery" -- with some areas of flowing or moving ice and other areas where the ice may have been stagnant, playing a protective rather than erosional role.  We need to get this picture into the heads of all those who take part in this debate, because too many people see the Irish Sea Glacier as something which had a sharp and definable edge to it.  Visions of vertical ice cliffs trundling in from the west......   I myself plead guilty to portraying the ice front as such, in an attempt to simplify and explain.  Maybe it's time to make things more complicated and more realistic.....