Ok is no more........

Seasonal snowpatches on the Ok plateau -- a winter photo.  The small crater in the centre of the plateau is the most obvious feature in this image.  This is all snow -- not glacier ice.

There have been a number of media stories over the past six months about the disappearance of Okjokull, a small plateau glacier sitting on top of an old volcanic cone not far from Reyjkjavik in Iceland.  It sure has gone, and there are records of ice over 50m thick here, just a few decades ago........  It was unusual in that it was completely circular, resting atop a symmetrical cone which had lost its tip.

https://www.bbc.co.uk/news/world-europe-49345912

https://www.bbc.co.uk/news/av/world-europe-49844050/a-memorial-to-iceland-s-disappearing-glaciers?SThisFB&fbclid=IwAR1sbAb6UOFhFPI5t9asXOmxM3a3quUcF_CzqUtdn2VJmISGPlRHVhi9CGg



However, the claim made on the BBC Travel Show that this was the first Icelandic glacier to entirely disappear because of global warming was not correct.  A number of small glaciers in Iceland were apparently thriving for a few centuries during the Little Ice Age -- a cold snap that lasted from approx 1550 to around 1890.  The dates and duration varied from one place to another -- and some believe that the Little Ice Age did not properly end until around 1947.

However, as pointed out on this blog,  Glamajokull, the southernmost of the two ice caps on the plateau of NW Iceland, was quite extensive around 1850, at the local culmination of the Little Ice Age -- and it had entirely melted away by the time of the great Danish mapping exercise in 1913-14.  In contrast, Drangajokull, a little further north, covered an area in 1850 that was almost three times as large as its present size.  It had shrunk dramatically by 1913-14, and has shrunk dramatically since then.  How much longer will it last?  Maybe thirty years, if we are lucky.........

The Ok plateau as it is today, close to the core of the old ice cap.

I'm rather interested in the appearance and characteristics of these ex-ice cap plateaux.  They are usually devoid of any morainic features and they may have no definable till either -- just a scatter of boulders that may or may not be erratic or far-travelled, and a patchwork of exposed rock surfaces and areas covered with rock rubble or breccia.  There may or may not be traces of rock smoothing or streamlining -- for in general, ice movement may have been sluggish at best and non-existent at worst.  That is what happens beneath ice sheds or ice cap summits;  the further you are from an ice cap summit, the greater the likelihood of ice moulding and other erosive activity.  For much of the history of an ice cap, the ice beneath the summit may actually be frozen to the bed, and there may not be much activity within the ice mass either.

 

Satellite image of part of the Glama Plateau, showing typical "knock and lochan" terrain

The highest part of Lambadalsfjall, which was at the heart of the Glama ice cap.  Now there are semi-permanent snowfields and no glacier ice -- and very few surface traces of glaciation.  No moraines or till cover -- just occasional frost-shattered rock outcrops