Been looking at Alun's model again. There is a lot of controversy about it -- not least relating to the extensive ice shown over the uplands of Devon and Cornwall. Some people will not accept that there was ever any ice cover over dartmoor and Exmoor -- but other geomorphologists beg to differ. Personally, I have no problem with a cover of thin cold-based ice maybe 100-200m thick, moving very sluggishly -- the landscape effects will have been minimal.
It gets much more interesting when we look at Somerset and Wiltshire. The ice is shown as covering the site of Stonehenge -- again this would have been thin, sluggish ice. But I'm quite intrigued by the idea that there was a divergent ice flow over Somerset, with ice coming in from the west and then being split into two streams, one on either side of the Mendips. The southern stream, which (according to this model) reached its greatest extent near Yeovil and Sherborne, must have travelled from the NW towards the SE. The northern stream, affecting the Bath area and pressing down towards Stonehenge, would have moved approx WNW - ESE. The southern ice stream -- simply on the basis of reconstructed ice movement directions -- would have been the one most likely to have carried Pembrokeshire erratics. The northern one might have carried more material from Mid Wales and the Marches. That opens up all sorts of exciting possibilities relating to the origins of the "unknown" rock fragments that have been showing up in some recent digs on Salisbury Plain.
What is most interesting about this new work is that it pretty well confirms what dear Geoffrey Kellaway said almost 40 years ago -- and for which he has been vilified by senior archaeologists (not to mention geologists and geomorphologists) ever since.......
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