A reconstruction of the Dartmoor Ice Cap after 1400 years of buildup -- around the time of the Devensian maximum ice coverage in the UK -- around 20,000 years ago. From the paper by Evans et al, 2012.
Earlier in the year I posted in item relating to the glaciation of Dartmoor -- commenting on a direct assault by a senior geomorphologist called Allan Straw on the paper by Evans et al (2012). This was the paper which I also covered in 2012, and which provided what was in my view very convincing evidence of a whole suite of landforms on the moor which could only be interpreted as the results of glacial ice on the landscape. (Do a search on the blog if you like -- put "Dartmoor Glaciation" into the search box.
http://brian-mountainman.blogspot.co.uk/2013/02/dartmoor-glaciation-disputed.html
Well, Evans et al have now hit back hard in a paper in Quaternary Newsletter 130 (June 2013), arguing out the issue point by point and effectively reinforcing everything in the original paper. Allan Straw has also been given the right of reply, but he does not make a very good fist of it, and as far as I am concerned, this is game, set and match to Evans, Harrison, Vieli and Anderson. The evidence and the theory are just too strong to wither away in the face of an attacker who provides no new evidence and who simply says "well, this and that MIGHT possibly be explained by other mechanisms......"
Last time round, somebody asked in a comment what this all as to do with Stonehenge? I repeat the simple point that if glacial processes were possible in the Devensian on quite a large scale on Dartmoor and probably Exmoor as well, as I have often suggested, then it is well within the bounds of PROBABILITY that Stonehenge was glaciated as well at some stage during the Pleistocene.
Anyway, it's good to see that there is robust debate in geomorphology, out in the open, where it should be............
6 comments:
Brian,
Your reporting on this study of the glaciation of Dartmoor is very relevant and important in our discussions here on Stonehenge. It is encouraging the science on this has been reinforced with a follow-up paper.
Question:If meteorological conditions resulted in the glaciation of Dartmoor, wont this also result in the freezing of any glacial lakes in the geographical proximity to Dartmoor?
Kostas
Kostas -- remember that even if there is an ice cap present on the upland, there is always melting going on around the edges. This means that any lakes in the vicinity will probably freeze in the winter and melt in the summer. High level lakes that might have been in the uplands prior to glaciation will simply be wiped out by the buildup of the ice cap.
Brian,
Perhaps small rivers and glacial lakes may freeze/melt each year. But would a much larger glacial lake (for example covering Salisbury Plain) frozen solid melt completely each year?
Kostas
Kostas -- for the umpteenth time, look at the map and look at the landscape. You are not going to get a lake on Salisbury Plain, no matter what crazy scenario you try to dream up.
Not a lake, Brian. But a glacial lake! With the Irish Sea Glacier encroaching along the Bristol Channel and SW coast. Forming a glacial dam creating a glacial lake. Which latter froze solid over 1300 years of freezing conditions during the Younger Dryas.
Kostas
Wonder what the late, lamented Professor Mick Aston, 1946-2013 [of Time Team fame, but much more], would have made of this? Mick's very first excursion into a Time Team - like programme was just north of Dartmoor.
Mick was also originally a Geographer at Birmingham University, and wrote a good deal on environmental factors in relation to archaeology - quite akin to the skills employed in Historical Geography. A modest man, I think he would have listened readily to the new evidence, and made his own mind up.
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