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Thursday, 24 November 2022

Glacial diffluence -- Kjove land, East Greenland


The hilly summits of the Kjove Land Plateau are seen clearly here, to the right of centre.  The five highest summits, including Pythagoras Bjerg, are not seen in this photo -- they are to the right of the right edge. They have altitudes of 1150m, 1335m, 1187m, 1190m, and 1376m. 
For comparison, Snowdon summit is at 1085m asl.

This new oblique image (taken from a helicopter) shows the Kjove Land - Syd Kap area of East Greenland where I worked in 1962 with the members of the OU East Greenland Expedition.  It reminds me that there is one big diffluence trough in the area, occupied by the twin lakes of Holger Danskes Briller, and also another which has previously escaped attention, on the southern flank of the lakes trough.  I'm not sure whether this valley has a name, but it's quite spectacular, showing up particularly well in this image of a snow-covered landscape:



The last occasion on which these troughs were used by glacier ice was during the "Milne Land Stage" at the end of the last glacial episode.  In the lakes trough the ice reached a prominent moraine with a "delta top" which demonstrates that relative sea-level at the time was 101 m higher than it is today.  The smaller trough was used by ice escaping from the lakes trough -- probably "forced" by ice additions to the Nordvestfjord Glacier carried by Oxford Glacier and other glaciers flowing southwards from the Staunings Alps. The high col over which the ice spilled is about 700m asl.  The ice flowed along the east flank of Pythagoras Bjerg and then fanned out across the gently undulating Kjove Land Plateau to terminate at the scattered morainic remnants referred to as "Hjörnemoraene"  (corner moraine) at an altitude of c 100 m.

https://brian-mountainman.blogspot.com/2021/09/on-diffluence-holger-danskes-briller.html

https://brian-mountainman.blogspot.com/2021/09/the-nordvestfjord-threshold.html

https://www.researchgate.net/publication/264811455_Deglaciation_of_the_Scoresby_Sund_fjord_region_north-east_Greenland

https://brian-mountainman.blogspot.com/2019/08/syd-kap-and-bear-islands-east-greenland.html



The Holger Danskes Briller terminal moraine and delta terrace, at an altitude of c 101 m


Some years ago I argued that the Kjove Land Plateau and Pythagoras Bjerg stood up as a nunatak at the time of the Milne Land Stage (c 11,000 years ago) and that the Hjornemoraene remnants were lateral moraine remnants formed on the right flank of glacier ice flowing southwards towards Syd Kap.  I don't think that's supported by the new information, and so I now think there was a local ice cap on this upland area, providing ice that flowed down into Nordvestfjord over very steep precipices in the west and down the small steep valley on the southern edge of the plateau.    The ice was supplemented by the diffluent ice stream overflowing from the lakes trough which terminated at the southern plateau edge.  This means that Hjornemoraene and the related morainic ridges extending over several km must be interpreted as terminal moraines, some of them aooarently marking a calving ice terminus.  The explains the close association with the shoreline traces around 101 m asl which David Sugden and I mapped in 1962.  This must have been a messy situation -- one day somebody will sort it all out........

The marine features and moraine remnants mapped by David Sugden and myself in 1962.

Probable directions of ice movement at the Milne Land Stage, around 11,000 years ago.


See also:

SUGDEN, D. E. and B. S. JOHN (1965) 'The raised marine features of Kjove Land, east Greenland', Geogrl. Jnl. 131, pp 235-47
https://www.researchgate.net/publication/262414669_The_Raised_Marine_Features_of_Kjove_Land_East_Greenland

Goehring, B. M., Kelly, M. A., Schaefer, J. M., Finkel, R. C. and Lowell, T. V. 2010. Dating of raised marine and lacustrine deposits in east Greenland using beryllium-10 depth profiles and implications for estimates of subglacial erosion. J. Quaternary Sci., Vol. 25 pp. 865–874. ISSN 0267-8179.
https://doi.org/10.1002/jqs.13


Funder, S. 1972
Deglaciation of the Scoresby Sund fjordregion, north-east GreenlandSVEND FUNDERInstitute of Historical Geology and Palaeontology, University of CopenhagenDeglaciation of the Scoresby Sund fjord region, north-east Greenland.
https://www.researchgate.net/publication/264811455_Deglaciation_of_the_Scoresby_Sund_fjord_region_north-east_Greenland


Helena Alexanderson & Lena Håkansson (2014) Coastal glaciers advanced onto Jameson Land, East Greenland during the late glacial–early Holocene Milne Land Stade, Polar Research, 33:1, 20313, DOI: 10.3402/polar.v33.20313
https://doi.org/10.3402/polar.v33.20313

Hall, B.L., et al., Relative sea-level changes, Schuchert Dal, East Greenland, with implications for ice..., Quaternary Science Reviews (2010),
https://doi.org/10.1016/j.quascirev.2010.03.013

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