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Sunday, 16 October 2016

Article on Hypothesized Scottish Precambrian Impact Crater

Article on Hypothesized Scottish Precambrian Impact Crater

Massive crater under small Scottish town could be the crash site of the first meteorite to hit the British Isles
Thought to be under the small town of Lairg, northern Scotland, it be one of the 15 largest known craters.
By Press Association and Libby Plummer, Mail Online, September 21, 2016
http://www.dailymail.co.uk/sciencetech/article-3800595/Massive-crater-small-Scottish-town-crash-site-meteorite-hit-British-Isles.html

It is certainly not the "first" meteorite impact in British Isles, as there undoubtedly have been older ones.
Instead, it might be simply the oldest known impact in the British Isles. (Presuming that older impacts certainly have occurred and not be either preserved of found.) Like all news articles, some of the substance of the science has gotten either lost or misinterpreted in translation to lay English.

An interesting observation is that the impact crater lies on a piece of crust composed of  Lewisian Gneiss that was part of Rodina. At the time that impact occurred, Rodina was being rifted apart to form Laurentia (prehistoric North America). This piece of crust ended up as part of the Laurentian continental margin. It was this rifting that created active rift basins, in which the Stoer and Sleat Groups accumulated and the ejecta blanket was buried and preserved. Thus, at the time the impact occurred, it hit within what became
prehistoric North America and only much later ended up on the opposite side of the Atlantic.

A recent abstract is:

Simms, M. J., 2016, A Buried Impact Crater in Scotland. 79th Annual Meeting of the Meteoritical Society (2016) abstract no. 6090.
http://www.hou.usra.edu/meetings/metsoc2016/pdf/6090.pdf

An older paper is:

Simms, M. J., 2015, The Stac Fada impact ejecta deposit and the Lairg Gravity Low: evidence for a buried Precambrian impact crater in Scotland? Proceedings of the Geologists’ Association. vol. 126, pp. 742–761

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