tag:blogger.com,1999:blog-1228690739485734684.post8617512560381117836..comments2024-03-18T23:11:23.676+00:00Comments on Stonehenge and the Ice Age: Where was the Anglian shoreline?BRIAN JOHNhttp://www.blogger.com/profile/00413447032454568083noreply@blogger.comBlogger6125tag:blogger.com,1999:blog-1228690739485734684.post-17869858488525602672010-12-02T17:26:11.052+00:002010-12-02T17:26:11.052+00:00Are you looking for clay on Salisbury Plain -- ie ...Are you looking for clay on Salisbury Plain -- ie on the chalk? There is plenty of clay around the edges of the chalk scarp -- Kimmeridge Clay, Oxford Clay etc. I'm sure I have also seen some refs to "clay pits" on the chalk -- will try to chase this up.BRIAN JOHNhttps://www.blogger.com/profile/00413447032454568083noreply@blogger.comtag:blogger.com,1999:blog-1228690739485734684.post-39798097478827586282010-12-02T15:31:30.962+00:002010-12-02T15:31:30.962+00:00Head and angular clasts That is bad news
If head c...Head and angular clasts That is bad news<br />If head clays were used in pots would they llok like clay pots tempered with cruched (angular0 rock temper.<br />GCU In two minds.Anonymousnoreply@blogger.comtag:blogger.com,1999:blog-1228690739485734684.post-46893597177849716552010-12-01T17:01:38.548+00:002010-12-01T17:01:38.548+00:00I said water tables -- not water levels. Differen...I said water tables -- not water levels. Different thins entirely.<br /><br />Which huge flood? You don't need huge floods to create valleys on chalk, or on any other rock type, for that matter.<br /><br />The soil layer is not the same as "head" -- the latter term is used for an accumulation of periglacial slope deposits. It has certain characteristics such as sharp clast shapes, upslope origin for everything, and pseudo-bedding.<br /><br />Soil layers on chalk are often quite thin on interfluves etc -- but at the base of slopes and in valleys solifluction can lead to great thicknesses.BRIAN JOHNhttps://www.blogger.com/profile/00413447032454568083noreply@blogger.comtag:blogger.com,1999:blog-1228690739485734684.post-71931097467745536572010-12-01T11:55:59.824+00:002010-12-01T11:55:59.824+00:00Interesting - water again!!
So the dry velleys in...Interesting - water again!!<br /><br />So the dry velleys in the south are from water levels - ok I can accept that!<br /><br />When was this huge flood that was powerful enough to cut 200' valleys in chalk? Taking into account the soil layer - I think you geologists call 'head' - is less than 1 meter thick? A layman would suggest recently!<br /><br />RJLRobert Langdonhttp://www.prehistoric-britain.co.uknoreply@blogger.comtag:blogger.com,1999:blog-1228690739485734684.post-55177574805094828492010-11-30T22:42:47.746+00:002010-11-30T22:42:47.746+00:00Gosh -- I am flattered to be accused of being very...Gosh -- I am flattered to be accused of being very conservative! Nice change from all the other stick I get, for rocking the boat too much.<br /><br />I have never read anywhere that the Downs are supposedly affected by glacier ice. The dry valleys of coombes are generally attributed to rising and falling water tables, and maybe to enhanced runoff at times of permafrost, when there may have been a lot of snow banks around. Because we are talking about chalk, solution has been a major factor as well. Mind you, I wouldn't eliminate the idea of a semi-permanent thin cover of firn (and maybe some rather stagnant ice) at times when the ice sheet edge was not far away, on the north side of the Thames valley. By the same token, Dartmoor and Exmoor might have had thin ice caps.<br /><br />The present isostatic uplift is of course attributed to the after-effects of the Devensian glaciation. But we can assume that there will have been an almost identical pattern of isostatic recovery (and eustatic rise) after each of the big glaciations -- dependent upon the pattern and rate of ice melting.<br /><br />Did the Anglian ice cover the WHOLE of the UK? I'd like to see some evidence... and the evidence I have seen doesn't seem to point that way. Most of the UK, yes. All of the UK? Don't think so.BRIAN JOHNhttps://www.blogger.com/profile/00413447032454568083noreply@blogger.comtag:blogger.com,1999:blog-1228690739485734684.post-20663583931274787662010-11-30T19:48:38.066+00:002010-11-30T19:48:38.066+00:00Brian - You views seem to be quite 'main strea...Brian - You views seem to be quite 'main stream' (with a little tinkering) including accepting that Anglian Glaciation, around 450,000 years ago reaching no further down 'Hornchurch' in Essex.<br /><br />The problem is if this is the greatest southerly effect of ice on Britain - how are the North and South Downs formed? I read that the 'traditional' theory was the water from Ice Caps carved out these 'Dry Valleys' not excluding Stonehenge Region - and you would need a long and sustained water flow over over 200' to damage the chalk downs to that extent.<br /><br />The second 'problem' is that currently 'whole' of Britain seems to be suffering 'isostatic rebound' in some form or other - so it is not possible that what is attributed to the Anglian Glaciation, around 450,000 years ago was in fact the last Glaciation 12,000 years ago?<br /><br />And therefore the Anglian Glaciation completely covered Britain - For I believe there are new findings that show the Anglian carved out the English Channel, which would explain the Downs in question.<br /><br />Robert LangdonRobert Langdonhttp://www.prehistoric-britain.co.uknoreply@blogger.com