How much do we know about Stonehenge? Less than we think. And what has Stonehenge got to do with the Ice Age? More than we might think. This blog is mostly devoted to the problems of where the Stonehenge bluestones came from, and how they got from their source areas to the monument. Now and then I will muse on related Stonehenge topics which have an Ice Age dimension...
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Monday, 4 October 2021
A nice little erratic boulder
On looking through my East Greenland slide collection from 1962 I came across this one. It's in Kjove Land, on a vast expanse of moraine-covered tundra -- a nice little erratic, probably dumped in the last glacier advance around 12,000 years ago.
8 comments:
Tony Hinchliffe
said...
We need to find one or two ( much smaller!) erratics on Salisbury Plain......pity we didn't recruit Daniel Craig, his stuntman and the entire film crew to scour The Plain during their filming of James Bond film " No Time To Die"......my money's on somewhere within 3 miles of Boles Barrow.
Serioudly, can you get an impression of the direction of travel of the ice from the alignment of the shape of the erratic, or is the process of ice capture too chaotic? Would distribution of erratics of similar material be a better indicator.
Hi Dave -- erratics tend to behave very erratically. Alignment is not exactly random, but you can't tell much from the way an erratic is lying, unless ice has streamed over it, in which case, if it is elongated, it will lie approx parallel to ice movement. Giant erratics like this one have probably been entrained by a process of massive block removal -- and this one has almost certainly travelled in or under the ice rather than on the surface, because it is quite heavily abraded. You can look up fans, trails and trains for previous posts on erratics....
Given that on this Blog our favoured glaciation is the ancient, Anglian one (over 450,000 years) as regarding a Stonehenge erratic train, do you consider there may be any surviving signs of the train's direction of travel in the surviving landscape formations?
Have you got any opinion about more localised landscape features that possibly retain some effects of any glaciation within 10 to 20 miles, say, of the Salisbury Plain escarpment? You mentioned Heytesbury parish - which encompasses Boles barrow, for example - in earlier Posts; also, we have discussed Clay Pit hill near Chitterne. Both the Chitterne and the Heytesbury parishes lie broadly west of Stonehenge and the earlier, west - east Great Cursus. There are many Early Neolithic long barrows near the Salisbury Plain escarpment (both below it in the vicinity of the Wylye valley, and above it). Somerset lies broadly westwards and north- westwards.
I have pondered a bit in the past on the shape of the hills in Somerset -- some of them do look like roches moutonnees, but I don't want to push that too hard because there may be structural control in some cases, and I would need to check out the local geology. The other features of interest are the combes or dry valleys, some of which are very spectacular and which look as if they have been fashioned in part by great volumes of meltwater. I have done some posts on the Mendip valleys, but some on the chalk scarp are rather intriguing too......... but the effects of chalk permeability and permafrost penetration have to be factored in to any analysis.
8 comments:
We need to find one or two ( much smaller!) erratics on Salisbury Plain......pity we didn't recruit Daniel Craig, his stuntman and the entire film crew to scour The Plain during their filming of James Bond film " No Time To Die"......my money's on somewhere within 3 miles of Boles Barrow.
Or a very small person?
Serioudly, can you get an impression of the direction of travel of the ice from the alignment of the shape of the erratic, or is the process of ice capture too chaotic? Would distribution of erratics of similar material be a better indicator.
Dave
Hi Dave -- erratics tend to behave very erratically. Alignment is not exactly random, but you can't tell much from the way an erratic is lying, unless ice has streamed over it, in which case, if it is elongated, it will lie approx parallel to ice movement. Giant erratics like this one have probably been entrained by a process of massive block removal -- and this one has almost certainly travelled in or under the ice rather than on the surface, because it is quite heavily abraded. You can look up fans, trails and trains for previous posts on erratics....
If Daniel Craig had been a geomorphologist, he could have kept an eye open for erratics in between stunts....
Given that on this Blog our favoured glaciation is the ancient, Anglian one (over 450,000 years) as regarding a Stonehenge erratic train, do you consider there may be any surviving signs of the train's direction of travel in the surviving landscape formations?
Hi Tony -- suggest you put in "Somerset" into the search box. Many posts have dealt with this issue.......
Have you got any opinion about more localised landscape features that possibly retain some effects of any glaciation within 10 to 20 miles, say, of the Salisbury Plain escarpment? You mentioned Heytesbury parish - which encompasses Boles barrow, for example - in earlier Posts; also, we have discussed Clay Pit hill near Chitterne. Both the Chitterne and the Heytesbury parishes lie broadly west of Stonehenge and the earlier, west - east Great Cursus. There are many Early Neolithic long barrows near the Salisbury Plain escarpment (both below it in the vicinity of the Wylye valley, and above it). Somerset lies broadly westwards and north- westwards.
I have pondered a bit in the past on the shape of the hills in Somerset -- some of them do look like roches moutonnees, but I don't want to push that too hard because there may be structural control in some cases, and I would need to check out the local geology. The other features of interest are the combes or dry valleys, some of which are very spectacular and which look as if they have been fashioned in part by great volumes of meltwater. I have done some posts on the Mendip valleys, but some on the chalk scarp are rather intriguing too......... but the effects of chalk permeability and permafrost penetration have to be factored in to any analysis.
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