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Thursday, 15 September 2022

Ice moulding on Carningli summit


It was good to meet up with fellow glacial geomorphologist Prof Peter Worsley the other day, while he and his wife Hilary were in the area on holiday.  We had not met up for the best part of fifty years......

Anyway, geomorphologists never do retire properly, and Peter and Hilary could not resist looking at some key sites like Poppit, Ceibwr and Carningli, as well as taking a look at the Limeslade erratic on the way home.  

The above photo (thank you Hilary!) shows Peter examining the smoothed and undulating dolerite surfaces towards the west end of the summit ridge.  He tells me that he too thinks these are signs of rather recent glacial moulding  -- probably dating from the LGM.  We have debated this issue before on this blog, given the cosmogenic dating work by Prof Danny McCarroll and others some years ago.  I have suggested that the summit of Carningli probably was submerged beneath streaming ice at the peak of the last glaciation -- with that suggestion underpinned by what we now know about glacial limits and features on the north side of the Mynydd Preseli ridge and indeed on the flanks of Carningli and Mynydd Dinas.  

I am also rather convinced that following a slight reduction in the altitude of the ice surface Carningli was a nunatak partly surrounded  by a windscoop.

There are still questions.  Are the moulding features solely Devensian in age, or are they older (inherited) features dating from one or more older glaciations and then slightly modified around 25,000 years ago?  We need more cosmogenic dates......


One of my photos of the same moulded surface near the summit

Ice moulded surfaces on the eastern flank of Carningli

2 comments:

Tony Hinchliffe said...

I understand that Professor Peter (and Mrs Hilary) Worsley are the parents of Lucy Worsley, presenter of various BBC programmes such as the " History's Biggest Fibs" series.

She needs to study the output of one Professor Mike Parker Pearson.......

BRIAN JOHN said...

Yes, there is indeed that family connection. But I imagine that the topics of each programme are nor decided by her, but by her producer. I don't know whether they ever did Piltdown Man, but in some ways the Bluestone Myth is even more carefully crafted and "sold" to a gullible world.......