On the Occurrence of Crag Strata beneath the Boulder-clay in Aberdeenshire

Abstract

I n the parishes of Slains and Cruden (see Map, p. 348) we have beds apparently of the same age as the English Crag formation. They consist of stratified sand and gravel underneath the boulder-clay, and reposing upon the old rocks of the district. I need not enter into any description of the locality in which these deposits occur, nor of their general character, as these will be found detailed in a paper on the Pleistocene of Aberdeenshire, which the Geological Society did me the honour of printing in the 14th volume of their Journal (see pp. 522–525). I had even at that time some suspicion of their Crag character, from their position below tho boulder-clay, and, further, from the total absence of any glacial striæ or polish upon the pebbles: but I have since then made a close search amongst the comminuted shell-fragments that are everywhere sparingly scattered through the mass; and it is from the character of these, combined with the geological position of the strata, that I infer the age to be probably that of either the Red or the Mammaliferous Crag of England. I have upwards of a score of hinge-fragments which I can safely refer to the Cyprina rustica or Venus rustica of Sowerby’s ‘Mineral Conchology’—a shell which is unknown in the drift-beds, and which, so far as I am aware, has been found only in the Crag; likewise a few fragments of the Fusus contrarius , another Crag form. The prevailing species of Pecten , so far