The Secondary Rocks of Scotland. Second Paper. On the Ancient Volcanoes of the Highlands and the Relations of their Products to the Mesozoic Strata

Abstract

For the preservation of the most valuable illustrations of the institutions, manners, and arts of Ancient Rome, the archæologist is indebted to the action of a volcano: the relics of Pompeii have survived in consequence of being buried under the ejections of Vesuvius. To a similar agency, operating at a distant epoch and on a far grander scale, the geologist owes the escape from destruction, in the Western Isles of Scotland, of most wonderful monuments of physical change and highly interesting records of life-history during the Secondary periods; for such, indeed, are those remarkably preserved fragments of sedimentary rocks which it is the object of this memoir to describe. As he prosecutes an examination and comparison of all the circumstances under which the scattered relics of the Secondary formations present themselves in the West of Scotland, the geologist will be again and again impressed by the extent of the protective influence which the vast masses of Tertiary lava have evidently exerted upon the subjacent stratified rocks. And when he has concluded that survey, he can scarcely have failed to arrive at the conclusion that, but for this protective influence, every vestige of the Mesozoic deposits in the district must have been inevitably swept away by denudation.