There seems to be something irresistible to many folk about having our very own glacier – even if it’s long gone.
A professor at Dundee University made the headlines this week with a claim that Coire an Lochain in the Cairngorms held a glacier as recently as the 1700s. The news seemed to excite everyone, and I have to admit to a small frisson myself. But why? Okay, 400 or so years ago is a lot more recent than the over 11,000 years conventional wisdom said had passed since the last Scottish glacier had disappeared but, all the same, it’s not as though we could go and poke it with an ice axe. Gone is gone, whether it’s 11,000 years or 400.
Anyway, the controversy opened up quickly when, writing the story up for the MCofS website, I asked the opinion of Adam Watson on the claims. He dismissed them as poorly researched and tested and said that if there was a ‘little ice age’ glacier in Scotland – which there wasn’t – it would have been in the Garbh Choire Mor, where, unlike Coire an Lochain, snows still lie through most summers.
But: the claims first:
Dr Martin Kirkbride, a geographer at Dundee University, said in his paper that Scotland’s most recent glacier – formed during the ‘Little Ice Age’ – possibly existed in the Cairngorms as recently as the 1700s.
He said it had long been understood that Britain’s last glaciers melted around 11,500 years ago, but that, by using modern dating techniques, he had shown that a small glacier had been formed in Coire an Lochain in the Northern Corries and had piled up granite boulders to form moraine ridges within the last few centuries.
He said: “Our laboratory dating indicates that the moraines were formed within the last couple of thousand years, which shows that a Scottish glacier existed more recently than we had previously thought.
“The climate of the last few millennia was at its most severe between 1650 and 1790. There are some anecdotal reports from that time of snow covering some of the mountain tops year-round. What we have now is the scientific evidence that there was indeed a glacier.”
Dr Kirkbride’s paper was backed by another from Dr Stephan Harrison at the University of Exeter and Dr Anne Rowan at the University of Aberystwyth, who developed a climate model to simulate Little Ice Age climate in the Cairngorms. Their paper argued that small glaciers would have been created in the corries by a cooling of air temperatures by 1.5C and precipitation increasing by ten per cent.”
Dr Harrison said: “Our findings show that the Cairngorm mountains were probably home to a number of small glaciers during the last few hundred years – around 11,000 years later than previous evidence has suggested.”
However, the claims of both sets of scientists were rejected by Dr Adam Watson, primarily an ecologist but who has made particular study of snow and long-lying snow beds in Scotland and in the Cairngorms in particular.
A chapter in his fascinating book, ‘A Snow Book, Northern Scotland’, based on over 70 years of observations and study, specifically deals with the 18th century glacier question and he is in no doubt that such a thing didn’t exist, the boulder moraines often claimed as evidence actually being built up by rockfall and avalanche debris.
To be fair, his chapter involved the Garbh Choire rather than Coire an Lochain but, after reading both papers, he said this week that one boulder ridge identified by Dr Kirkbride as a moraine (pushed up by a glacier) was, in fact, a protalus rampart, fed annually by boulders, soil, vegetation and other debris coming down in avalanches.
He said: “In areas of acidic bedrock, such as the granite of the Cairngorms, a moraine has a clearly defined profile with different soil horizons. These include very thin acidic dark horizons above a dark greyish horizon (all these combined often called ‘topsoil’ by laymen), above a strongly coloured orange-brown sandy or gravelly ‘subsoil’. Other glacial deposits, till or boulder clay under the glacier and fluvio-glacial deposits washed out by glacial rivers, have their own characteristic horizons. This differentiates them more clearly and reliably than any surface measurements by geomorphologists.”
He said the Kirkbride paper was typical of studies by geomorphologists “who fail to dig a single soil pit and ignore fundamental principles of soil science.”
And he added: “This failure includes Sugden, who made the original proposal of glaciers in several corries of the Cairngorms in the 1700s and one in Garbh Choire Mor in the early 1800s.
“Both the 2014 papers state clearly that there was no soil profile in the supposed morainic ridges that they described. This rules out moraines without further ado.
“Both papers are uncritical in dismissing the possibility of protalus ramparts on the basis of the authors’ personal opinions on the unlikelihood of boulders and other debris travelling so far in avalanches. This signifies that they have never witnessed avalanches in these corries or their aftermath that can be seen in photographs.”
And he concluded: “The claim in Kirkbride about moraines in Coire an Lochain of Cairn Gorm is particularly unlikely. A snow patch survives till winter during very few years in that corrie, whereas in Garbh Choire Mor the patches almost always survive till winter, and hence this is the most likely site for a glacier in Scotland.”
However, Dr Kirkbride has stood by his paper.
He said: “I don’t have Adam’s experience of the Cairngorms – I doubt anybody does. But I have been visiting the Cairngorms for over 30 years, in all seasons, and I share his appreciation of the role of avalanches in modifying the landscape. Before writing our paper, we carefully considered several possible explanations for the boulder ridges before interpreting them, on the balance of a variety of evidence, as glacial moraines.
“The key point with regard to the moraine ridges that we describe in our paper is that the larger avalanches actually start at this height in the corrie, and move boulders from here further down the slope. The glacier has deposited the boulder ridges in a different place from where the avalanches do: in fact, it’s snow avalanches in springtime which are gradually destroying the glacial moraines at the present day by eroding debris from them, not creating them.
“The ridges themselves are in the wrong orientation with respect to the cliff above to have been deposited by snow avalanches, as we explain in our paper.”
Dr Kirkbride said he agreed that further work on soil profiles would be useful, but said it was not true that he didn’t dig a soil pit to examine this. “The deposits are not old enough to have well-developed soil profiles on them, unlike the 12,000 year-old moraines elsewhere in the Cairngorm corries,” he said.
So there you have it: a clash of experts. Though Adam Watson is primarily known as an ecologist rather than a glaciologist, he brings a scientific rigour to the question (especially when you read the full Chapter 6 of his book) which is hard to argue with. But who’s to gainsay the expertise of Drs Kirkbride etc? I don’t think they hand out university professorships in lucky bags.
I suppose an ideal outcome would be for the two men to work together, bringing each of their expertise to the table and producing a joint paper. Maybe that would seem too much of a duel, with a winner and a loser, but I’d hope that both men are bigger than that and would be more interested in settling a question that clearly fascinates people.
Great. Settled. Now all they need is the time…
Since writing this post I’ve found a very apposite article on the ukHillwalking site, written by Dr Kirkbride and one of his colleagues, answering Dr Watson’s criticisms. It’s very worthwhile reading and can be viewed here.
And, at the risk of endless scientific duelling, here’s a more complete version of Adam Watson’s argument: http://www.winterhighland.info/forum/read.php?2,160860,160987#msg-160987