Here is a most satisfactory view of the structure of this country on each side of the Rhône; strata of lime-stone and schisti, almost horizontal or little inclined, compose the mountains from their most lofty summits to the deepest bottom of those valleys. Such mountains cannot have been formed in any other manner than by the waste and degradation of their horizontal strata; consequently, here we are certain, that, from the summit of the Gemmi to those upon the other side of the Rhône, all the solid substance had been hollowed out by water. Thus were formed the valleys of the Rhône, the Dala, and a multitude of others. M. de Saussure has given us a description of a tract of alpine country of the same kind with that of the _Vallais_ now considered, so far as the strata are here in a horizontal position, instead of that highly inclined situation in which those primary bodies are commonly found. It is the description of Mount-Rosa Journal de Physique, Juillet 1790. Here the same interesting observation may be made with regard to the immense destruction which must necessarily have taken place, in the elevated mass of solid earth, by the dissolving or wearing power of running water; and this will be clearly explained by the formation of those mountains and valleys, which, while they correspond with mountains and valleys in general, have something particular that distinguishes them from most of the Alps, where the strata, being much inclined, give occasion to form ranges of peaks disposed in lines according to the directions of the inclined strata. Here on the contrary, there being no general inclination of the strata to direct the formation of the peaks, they are found without any such order. I shall give it in M. de Saussure's own words. «En effect toutes les hautes sommités que j'avois observées jusqu'à ce jour sont ou isolées comme l'Etna, ou rangées sur des lignes droites comme le Mont-Blanc et ses cimes collaterales. Mais là je voyois le Mont Rose composé d'une suite non-interrompue de pics gigantesques presqu'égaux entr'eux, former un vaste cirque et renfermer dans leur enceinte, le village de Macugnaga, ses hameaux, ses pâturages, les glaciers qui les bordent, et les pentes escarpées qui s'élèvent jusqu'aux cimes de ces majestueux colosses. «Mais ce n'est pas seulement la singularité de cette forme qui rend cette montagne remarquable; c'est peut-être plus encore sa structure. J'ai constaté que le Mont-Blanc et tous les hauts sommets de sa chaîne sont composés de couches verticales. Au Mont-Rose jusqu'aux cimes les plus élevées, tout est horizontal ou incliné au plus de 30 degrés.