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Tuesday, 24 January 2012

Preseli in the conflict zone


Preseli in the conflict zone again --  this time it's not a conflict between archaeologists and geomorphologists, but between the Irish Sea Glacier and the local Preseli Ice Cap. 

I published the top map some time ago, as my current best estimate of where the Irish Sea Glacier skidded to a halt in the Devensian Glaciation.  I did suggest at the time that because there are ice-smoothed rock surfaces on the summit ridge of Carningli, and because there is a lot of fresh till and an erratic spread over the ridge and down onto the south side, the glacier might have crept over the ridge and extended down towards the Gwaun Valley. 

Anyway, look at the cosy fit between my suggested southern ice limit and the northern edge of the Preseli Ice Cap, as modelled by Henry Patton and others.   My dotted area is not that different from the proposed ice-covered area.   I find that rather satisfying -- a nice convergence between desktop studies and fieldwork.

There are still a couple of big questions here.  First, what was the role of the proposed "Glacial Lake Brynberian" in the sequence of events here?  Second, was the maximum extent of the Irish Sea Glacier exactly in phase with the maximum extent of the Preseli Ice Cap?  We are talking about a period of maybe 1500 years -- a very short time, geologically.

Watch this space.  There will be developments.

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