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.