On the Distribution of the Superficial Detritus of the Alps, as compared with that of Northern Europe

Abstract

R eferring to his previous memoir upon the structure of the Alps and the changes which those mountains underwent, the author calls attention to the fact, that as during the formation of the molasse and nagelflue a warmer climate prevailed, so after the upheaval of those rocks an entire change took place, as proved by the uplifted edges of such tertiary accumulations being surmounted by vast masses of horizontally-stratified alluvia, the forms of whose materials testify that they were deposited under water. The warm period, in short, had passed away and the pine had replaced the palm upon the adjacent lands, before a glacier was formed in the Alps or a single erratic block was translated. Though awarding great praise to the labours of Venetz, Charpentier and Agassiz, which have shed much light on glaciers, and particularly to the work of Forbes for clearly expounding the laws which regulate their movement, Sir Roderick conceives, that the physical phænomena of the Alps and Jura compel the geologist to restrict the former extension of the Alpine glaciers within infinitely less bounds than have been assigned to them by those authors. True old glacier moraines may, he thinks, be always distinguished, on the one hand, from the ancient alluvia, and on the other from tumultuous accumulations of gravel, boulders and far-transported erratic blocks, as well as from all other subsequent detritus resulting from various causes which have affected the surface. He first shows, from the remnants of the old water-worn alluvia which rise to