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Friday, 13 August 2010

More about that BIG glaciation



UK ice limits of various ages. Source: "Age limits on Middle Pleistocene glacial sediments from OSL dating, north Norfolk, UK." by Steven M. Pawley et al

There have been more recent articles about ice limits in the UK, and how they are defined. there is still much confusion about what happened between the Devensian (Last Glacial Maximum) limit of around 20,000 years ago and the Anglian ice limit dated to around 380,000 - 450,000 years ago. In between there are various glacial deposits and traces variously referred to as Gipping, Saalian, Riss, Wolstonian and by assorted other names. It appears that across England the ice advances (if there were indeed several) appear to be overlapping and confused -- maybe more extensive in some areas and less in others, and sometimes incorporating/recycling pre-existing deposits. All very confusing.

Increasingly it looks as if the Anglian Glaciation occurred during Marine Isotope stage 12, and that the Saalian Glaciation (which may include a multitude of sins) occurred during Marine Isotope Stage 8.

So we are homing in here on the Anglian Glaciation as the time of the GBG (Greatest British Glaciation). There is nothing new there -- Kellaway and others first suggested this decades ago -- but it is gratifying that modern research in East Anglia and elsewhere is confirming this old hypothesis. Now all we have to do is fix the precise glacial limit at this time. As I have argued before, the limit is well beyond the ice edge position shown on the above map -- I'm pleading with geomorphologists to get stuck in on this problem, and to come up with an answer.

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