Altyre and Lethen Bar, two Middle Old Red Sandstone fish localities?

Abstract

Synopsis The Altyre Collection of Middle Old Red Sandstone fishes (made by Lady Gordon Cumming between 1839 and 1842) contained many specimens initially described by Louis Agassiz in his Monographie des Poissons Fossiles du Vieux Gres Rouge, of 1844–1845. There is a contradiction in the literature as to whether this material came from Lethen Bar, Nairnshire as recorded by Agassiz or the Altyre Burn as stated by Murchison in 1859. Its recent curation together with related historical research, have shown that the collection was made at Lethen Bar and that Murchison was wrong, although it is difficult to pinpoint a good reason for his error. The strata in the Altyre Burn are Upper Old Red Sandstone and the small wedge of Middle Old Red, which was included in this area on the 1″/1 mile Geological Survey map on the strength of Murchison’s 1859 statement, apparently does not exist. The most probable location for the original quarry at Lethen Bar is deduced from historical sources, and a short account of its working is given.