II.—Moraines and Mud-streams in the Alps

Abstract

It has often occurred to me during my Alpine wanderings that masses of earthy material containing boulders are too readily identified as moraines. That the latter exist, both here and in other mountain regions, no one would for a moment dispute, but deposits, sometimes very closely resembling till, may be produced in other ways. One is by a bergfall. The result of this in some cases, as at Goldau, Plurs, near San Vito (Ampezzo road), or the Col de Cheville, can be easily recognized; but when the fallen material consists largely of shale and friable rock, when there is a certain admixture of boulders from a distance (formerly perched blocks), its origin is not so readily determined. The enormous mass of débris on the north bank of the Rheinthal, between Chur and Ilanz—a mass which extends from Digg, through Flims, to rather beyond Laax, consisting of earthy stuff, probably mainly smashed shale or slate, and of boulders, apparently limestone—is regarded as bergfall by the Swiss geologists, and yet any section in it might readily be taken for moraine. Even more moraine-like in general aspect are the singular mounds of débris in the valley of the Rhone near Sierre.