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Wednesday, 29 October 2014

Was Cardiff Bay affected by Devensian ice?


With reference to my earlier post about the position of the Devensian ice front on the southern flank of the Welsh Ice Cap, there is still disagreement among geomorphologists.

This section of the BRITICE Devensian map shows abundant glacial / fluvioglacial deposits in the Cardiff - Newport area, but the compilers of the map decided that the Vale of Glamorgan was ice-free at this time, as was the coastal stretch to the east of Lavernock point.  The dotted line on the map shows the assumed maximum ice front position.

In contrast, Devensian ice lobes are assumed to have reached the Bristol Channel lowlands (ie beyond the present coastline) both in Swansea Bay and Carmarthen Bay.

My earlier post is here:
http://brian-mountainman.blogspot.co.uk/2014/10/flat-holm-erratic-hunt-6-lets-imagine.html

The extensive spreads of ice-related deposits shown on the map were assumed by Charlesworth in 1929 to represent the position of the South wales End Moraine, but it's now known that things were much more complicated than that.  Some of the deposits on the map are Devensian, and some may well be much older.......  In some of the reconstructions by Prof DQ Bowen over the years, he has an ice lobe pushing offshore between Cardiff and Newport, and in others the lobe fails to reach the coast.  Work in progress?

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