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Wednesday, 14 June 2017

Deglaciation of Fennoscandia

I've been looking at a fascinating new paper on the deglaciation of Fennoscandia following the LGM (last glacial maximum).  Here is the source of the maps to follow:

Arjen P. Stroeven et al, 2016. Deglaciation of Fennoscandia. Quaternary Science Reviews, Volume 147, 1 September 2016, Pages 91-121

The images below are high definition, so it should be possible to enlarge them by clicking.

 Main retreat stages.  The most interesting thing about this map is the highly crenulated ice edge on the European mainland, south of the Baltic.  This is a much more accurate mapping than anything done earlier, and it is what one would expect -- an ice edge running out of steam (if you see what I mean) on undulating terrain, pushing into lowland valleys and held up by hills and ridges.  Also, this map shows for the first time the full extent and scale of eskers within the area being deglaciated.  They are incredibly accurate indicators of ice movement directions at the time when the ice was wasting.

 Map showing the main dating points used by the authors in their reconstructions.  In recent years luminescence dating, improved radiocarbon dating and cosmogenic isotope dating have provided a sound database from which ice edge positions can be calculated -- but interestingly enough, the old Swedish varve chronology (developed by Dr Geer and others) was not very far out.......

Main identified ice retreat stages.  The red lines show the retreating ice edge before the Younger Dryas.  The yellow lines show the retreat after 12,700 cal yrs BP.  Note that around 10,200 years ago the remnant of the ice sheet broke into two in the Scandinavian uplands.  Around many of the coasts of the Gulf of Bothnia the ice edge was afloat as it retreated, because the land surface was deeply depressed isostatically.


TonyH said...

Brian's total Pageviews now nearing 1.2 million! Growth is almost exponential nowadays....but it's quality, not quantity, Senior Archaeologists please note.

BRIAN JOHN said...

Yes, page views go up and down --- depending, to some degree, on how much arguing is going on! We need another nice controversial paper that we can argue about. Myris, where are you when we need you?