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Wednesday, 16 February 2011

More on the Celtic Sea Piedmont Glacier

On looking back over some earlier references on this, I rediscovered this:

 Quote from Hubbard et al 2009:

"Without preconditioning certain large but critically limited zones
of the Irish Basin to a priori streaming, it is difficult to achieve
a single ‘surge-advance’ south to the Scilly Isles without a broad
piedmont type-lobe impinging onshore across much of SW
England. The reconstruction inferred in the E109b2 experiment
with a high precipitation scenario across western Britain may be
exaggerating the case somewhat but this simulation does tantalisingly
still meet all of the available ice-directional and RSL
constraints. Further enhancing precipitation rates across SW Eire
up to and exceeding present day values would yield a considerably
more western dominated Irish Sea ice-mass that would bring
modelled ice limits, especially those associated with the ISIS in SW
England, into line. However, there is little palaeo-climatic evidence
nor GCM modelling to support a wetter LGM than present across
southern Eire. Within the limitations of this study, we do not
pursue this though further investigation is clearly required."

So what evidence is there for a big ice dome over Southern Ireland around 23,000 - 20,000 years ago?   Work on the south coast of Ireland by O'Cofaigh and Evans (2007), backed up by many radiocarbon dates, shows that there was an incursion by the Irish Sea Glacier which was pushing westwards after passing through St George's Channel.  However, after that the irish Sea Glacier was displaced by ice pouring out from the Irish Midlands and the SW mountain areas, leading to the deposition of local tills (which go by a variety of local names) on top of classic Irish Sea till.  What we do not know is how protracted this "Irish Ice" episode might have been.

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