Glacier and rock mapping: solving some problems with Google Earth and the RGI
Brian Whalley
Glaciology Research Group
Università degli studi di Milano
Università degli studi di Milano
Glacier and rock mapping: solving some problems with Google Earth and the RGI
Hi Brian
Not quite sure if we can solve the dispute here or will ever be able to do so, but from my view of Google Earth images and considering the dynamics of glacier flow (e.g. leaving depressions in the bed-rock) and their response to climate change, I would estimate that about 90 to 95% of all rock glaciers on Earth are talus-derived creeping permafrost bodies that had never any relation to a former or current glacier. Only where the tongues of debris-covered glaciers (or ice-cored moraines) are located in the permafrost zone, there is a chance that glacier ice might contribute to the ice content of rock glaciers. But otherwise I am not so sure …
All the best, Frank
Dear Frank, how big (how long) do you think talus-derived rg can be? – ian Evans
Hi Ian, I would say several km, the longest ones likely > 10 km. Best, Frank
Hi Frank,
Yes, I am sure the debate will go on. However the mechanical properties of ice-rock mixtures have always been against the permafrost model (the mixture is just too ‘stiff’). But when you start to look at landsystems, ie beyond the immediate rock glacier, there is absolutely no reason to think that a glacier is not involved. Have a look at the paper on Gruben (Geografiska Annaler 2020). I show that Wilfried is quite wrong (as I explained 40 years ago!) but he has never belived it! Google Earth will supply the answer!
Anyway, we shall see
Best Wishes
brian