On the Superficial Accumulations of the Coasts of the English Channel, and the changes they indicate

Abstract

The geological phaenomena which form the subject of the present communication have hitherto been included under notices of “Raised Beaches,” or of “Recent Changes of Level;” they have invariably been considered as illustrations of the latest vertical movements of the earth's crust, as referable to one single period of time, and as mostly of small amount. My object will be to show that the phaenomena in question are much more complicated, that they imply a vast period of time, that one most important character has been entirely overlooked, and that taken together they help to explain the history of what is perhaps the most striking of the changes in its physical conditions which the Northern hemisphere has experienced—namely those which occurred during the Pleistocene period. The consideration of the evidence which any one of these masses, known as raised beaches, presents, will be the best introduction to the notices which follow. It must be borne in mind that no traces of such accumulations, sufficiently clear for our purpose, will be found along those parts of the coast-line of the English Channel which consist of yielding strata; from which we may infer that the period of the present sea-level has been of sufficient continuance to allow of the cutting back of such coast-line to points beyond the original extension inland of such accumulations. The phaenomena to be described are to be first observed on the coast of Devon, at the point where the older slates and limestones emerge from beneath the