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Wednesday 17 July 2019

Liverpool Land piedmont glacier apron

There is evidence in eastern Jameson Land of till having been laid down by westward-flowing glaciers.  These came from the Liverpool Land mountains and coalesced into a broad apron filling a wide transverse trough.  When the ice in the apron thickened sufficiently, flow was diverted northwards and southwards.

On this Google image we can see what a substantial through valley this is.  During the Late Devensian the piedmont glacier apron that occupied it was so thick that it spilled westwards onto the higher part of Jameson Land.

We have talked a lot about piedmont glaciers on this blog, in relation to glaciers decanting from troughs or fjords out onto adjacent lowlands — but not much about piedmont APRONS.  These are rather interesting, since they consist of  coalescing piedmont glaciers which spread laterally.

The Liverpool Land (East Greenland) example is an interesting one, and a number of authors have referred to the wide apron of glacier ice that filled the deep through valley connecting Hurry Fjord in the south to Carlsberg Fjord in the north.  This happened in the last glacial maximum (LGM) and probably in all preceding glaciations as well.  The glaciers flowing westwards came from the alpine mountain range of Liverpool Land.  On the east side of the mountains the glaciers coalesced on the open coast, and there may well have been a calving ice shelf.

According to the reconstructions, the coalescing piedmont glaciers filled the transverse trough and then flowed northwards and southwards towards the coast.  This must have happened in multiple locations in the arctic — and we can see examples today from Greenland, Arctic Canada and Arctic Russia.  We have referred in an earlier post to Putorana:

Putorana — the mountain front runs across the photo, and the morainic loops show how the individual glaciers coalesced into an extensive ”glacier apron”.

Here are some more classic photos of piedmont (unconstrained) glaciers -- in Arctic Canada and north Greenland:

In the above photo three piedmont glaciers have combined to create an apron.

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