Tuesday, 2 March 2010

Fresh insights into the glaciation of Scotland: Tom Bradwell at the Inverness Field Club


A couple of weeks ago I attended one of the Inverness Field Club's winter lectures. Despite having very nearly used up half my biblical allocation, I was the youngest person in the audience by a considerable margin. I had been coaxed into this gathering of the grey-haired, this amalgamation of the aged, this exhibition of the elderly, to listen to Tom Bradwell of the British Geological Survey giving a talk entitled '150 years since Darwin and Geikie: what do we really know about the Glaciation of Scotland?'. Last year I announced that I was embarking on a quest to understand the glacial landforms of Scotland in more detail so the effect of this title on me was similar to the effect on a jakie of telling him that a cider lorry had shed its load round the corner. 

I expected it to be interesting but it was truly mindblowing. I discovered that many of the things that I was about to teach myself have been overturned by recent research findings. These new insights have resulted from the availability of new datasets; detailed maps of the sea bed that have been created using sonar data from GPS equipped fishing boats. The waters of Scotland are so well fished that the coverage of these maps is complete - fishing boats have sailed over every patch of seabed, save for a few areas very close to the coast. The maps reveal that the sea bed,  right out to the very margin of the continental shelf, is littered with glacial landforms. While this is good news for geologists and interpreters of landscape, one cannot help but feel that it is somewhat less favourable for the cod and his fishy friends who genuinely have nowhere left to hide from this industrial scale factory fishing. 

This is extremely exciting because it has allowed geologists to confirm, for the first time, the extent of the ice sheet during the last glacial episode. Great ice streams flowed into the sea, notably northwards up the Minch and out into the Moray Firth, the British Ice Sheet merging with the Scandanavian Ice Sheet in the middle of the North Sea and flowing northwest towards the margin of the continental shelf. This data, along with temperature data from ice cores, has been used to create animations of how the ice sheet expanded and receded. The animations are linked at the bottom of this page. The colours represent the speed of ice flow, with red indicating faster flow. The sea level is also represented. The image is below isn't the best quality because I photographed it from my laptop screen using my phone. Have a look at the full videos, I hope you enjoy them as much as I did.

Image showing extent of ice sheet 22,300 years ago. From the Britice project

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