270. The granite ranges of Mont Blanc are as interesting to the geologist as they are to the painter. The granite is dark red, often inclosing veins of quartz, crystallized and compact, and likewise well-formed crystals of schorl. The average elevation of its range of peaks, which extends from Mont Blanc to the Tete Noire, is about 12,000 English feet above the level of the sea. [The highest culminating point is 15,744 feet.] The Aiguille de Servoz, and that of Dru, are excellent examples of the pyramidal and spiratory formation which these granite ranges in general assume. They rise out of immense fields of snow, but, being themselves too steep for snow to rest upon, form red, bare, and inaccessible peaks, which even the chamois scarcely dares to climb. Their bases appear sometimes abutted (if I may so speak) by mica slate, which forms the southeast side of the Valley of Chamonix, whose flanks, if intersected, might appear as (in _fig._ 72), _a_, granite, forming on the one side (B) the Mont Blanc, on the other (C) the Mont Breven; _b_, mica slate resting on the base of Mont Blanc, and which contains amianthus and quartz, in which capillary crystals of titanium occur; _c_, calcareous rock; _d_, alluvium, forming the Valley of Chamonix. I should have mentioned that the granite appears to contain a small quantity of gold, as that metal is found among the granite debris and siliceous sand of the river Arve [_Bakewell_, i. 375]; and I have two or three specimens in which chlorite (both compact and in minute crystals) occupies the place of mica. J. R. _March_, 1834. * * * * * With this paper were printed some observations on it by the Rev. W. B. Clarke, after which (p. 648) appears the following note by J. R. * * * * * 271. "TWISTED STRATA.--The contortions of the limestone at the fall of the Nant d'Arpenaz, on the road from Geneva to Chamonix, are somewhat remarkable. The rock is a hard dark brown limestone, forming part of a range of secondary cliffs, which rise from 500 feet to 1000 feet above the defile which they border. The base itself is about 800 feet high. The strata bend very regularly except at _e_ and _f_,[28] where they appear to have been fractured. * * * * * _To what Properties in Nature is it owing that the Stones in Buildings, formed originally of the frailest Materials, gradually become indurated by Exposure to the Atmosphere and by Age, and stand the Wear and Tear of Time and Weather every bit as well, in some instances much better, than the hardest and most compact Limestones and Granite?_[29]