1884.] on the Building of the Alps. 55 



I pass now to two other sections: of these the first is in the 

 neighbourhood of Pontresina. Most of the peaks in this region 

 consist of igneous rocks, of gneisses, and of schists, but some of later 

 date are not wanting — as, for example, may be seen in the flanks of 

 well-known Heuthal. These last are limestones of Triassic age. 

 Here they overlie unconformably a coarse gneiss — in other places 

 they rest on schists presumably of later date ; in fact, the series of 

 mesozoic rocks of which the above limestone is the lowest member — 

 though now to a great extent removed by denudation — has clearly 

 once passed transgressively over the whole series of gneisses and 

 schists of the Engadine. 



The second section, or rather group of sections, is some distance 

 away to the south-east, in the region of the Italian Tyrol. Those 

 magnificent crags of the Dolomite mountains, the serrate teeth of the 

 Eosengarten and the Langkofel, the towers of the Cristallo and the 

 Drei Zinnen, the precipitous masses of the Blattkogel and the 

 Marmolata, are built up of rocks of Triassic age, not of a very 

 difierent date from the soft red marls which occupy so large an area 

 in the Midlands of England. Follow me for one moment by the 

 mountain road from Predazzo to Primiero. At the former place — 

 classic ground for geologists — we are surrounded by great masses of 

 igneous rocks, the roots, it may be, of long-vanished cones, although 

 we refuse to recognise a crater in the valley about Predazzo. As we 

 ascend towards the beautiful Alps of Paneveggio, we pass for a 

 considerable distance over a great mass of red felstone. This belongs 

 to a group of igneous rocks which extend to the westward even 

 beyond the Etsch. It is overlain by the beds of the Trias, commenc- 

 ing with the red Grodner sandstone and passing up soon into the vast 

 masses of Dolomite which form the wild crags of the Cimon della 

 Pala and its attendant summits. But as we descend on the other side 

 of the pass towards Primiero we see the Triassic rocks, without the 

 intervention of the felstone, resting upon mica schists, similar to those 

 which occur in many other parts of the Alps. Sections of the above 

 kind, were it needful, might be multiplied indefinitely to prove that 

 between the base of the Trias and the Alpine schists and gneisses 

 there is an enormous break, but we may content ourselves with one 

 other, interesting not only for the completeness of the demonstration 

 but also for the mode in which it illustrates Alpine structure. 



[Attention was then directed to the section of the Mont Blanc 

 Eange, after Favre.] 



The Aiguilles Rouges are composed of coarse gneisses and crystal- 

 line schists, but on the highest summit there remains a fragmental 

 outlier of stratified and unaltered rock. The upper part of this is 

 certainly Jurassic. Below this comes a representative of the Trias — 

 much attenuated, as it is generally in this western region, with possibly 

 a remnant of a deposit of Carboniferous age. Be that as it may, there 

 is undoubtedly here a great break between the crystalline series and 

 the succeeding mesozoic or palaeozoic rock. 



