How much do we know about Stonehenge? Less than we think. And what has Stonehenge got to do with the Ice Age? More than we might think. This blog is mostly devoted to the problems of where the Stonehenge bluestones came from, and how they got from their source areas to the monument. Now and then I will muse on related Stonehenge topics which have an Ice Age dimension...
THE BOOK Some of the ideas discussed in this blog are published in my new book called "The Stonehenge Bluestones" -- available by post and through good bookshops everywhere. Bad bookshops might not have it.... To order, click HERE
Friday 2 February 2024
Løberen -- Greenland's galloping glacier
I found this in an article about Greenland glaciers, in the context of a section on East Greenland. Løberen is just one of a number of surging glaciers in the Staunings Alps, and their behaviour is still not well understood. Anyway, the graph shows that the little glacier in question (the dashed line) advanced c 7.5 km in the period 1955-1965, with a peak rate of advance of c 1 km per year. We worked on the glacier next door -- Oxford Gletscher -- in August 1962, blissfully unaware of what was going on in the next valley a little further up the fjord. At that time it seems that Løberen reached the sea, so there must have been a calving ice front.
The graph shows, for comparison, the behaviour of two fairly normal glaciers in West Greenland, and one "pulsing" glacier.
Satellite Image Atlas of Glaciers of the World GREENLAND By ANKER WEIDICK US Geological Survey Professional Paper 1386-C
When glaciers surge, yo9u get5 chaotic patterns on the glacier surface, and after the surge extensive areas of "pitting" or rapid melting because large amounts of ice have been transported to situations far below the firn line where ablation rates are high.
Anyway, since 1962 the glacier front has retreated far back up the valley to more or less its pre-surge position.
Here are two of the other glaciers in the Staunings Alps area that have surged within living memory.
Bjornbo Glacier in the Schuchert Valley
Oxford Glacier, on the north shore of Nordvestfjord
PS. You can recognize surges withy a fair degree of certainty in satellite imagery by the strange loops of moraine which disrupt the normal orderly arrangement of moraines that separate parallel streams of ice within the glacier. Sometimes the loops associated with surging tributary ice streams push right across a glacier and impinge upon the opposite valley wall.......