196 PROCEEDINGS OF THE GEOLOGICAL SOCIETY. [DeC. 13, 



eastern shore of the lake of Lowerz, as on its western banks. The 

 great accumulations of nagelflue and molasse of the Rossberg in 

 the one case, like those of the Rigi on the other, instead of dipping 

 away from the Alpine centre, plunge towards it ; the younger ter- 

 tiary rocks seeming to be the oldest by their order of superposition ; 

 whilst the nummulitic and flysch formation is broken and squeezed 

 up against the cretaceous rocks of the My then. In stating my 

 belief that the summits of the Mythen are of the age of the chalk, 

 1 would not, however, infer that the lower part of the mountain is 

 also of this age ; for at the eastern face, when examined from Brun- 

 nen, in the valley leading to Einsiedeln, it presents a great succes- 

 sion of underlying massive terraces, the lowest of which are highly 

 altered, siliceous rauchwacke limestone, with partial dolomitic veins 

 not unlike the " cargneule" of Savoy. In the vertical faces of the 

 limestone beneath the red peaks, the lines of stratification are ob- 

 scurely perceptible, seeming to pass to the S.S.W. ; whilst the whole 

 is traversed by highly inclined joints resembling a rude cleavage, the 

 planes of which plunge 70° to the N.N.W. As this mountain is to 

 a great extent inaccessible, and as the lower portions of it seem to 

 have undergone great modification, it is one of the countless examples 

 which the Alps oifer, of the difficulty of defining with precision the 

 downward limits of formations. 



Nummulite and Flysch Rocks of the Environs of Einsiedeln. 



Vast masses of flysch* lie between the Mythen and the valley of 

 Einsiedeln ; and to the west and south of that town, terraces of 

 nummulitic limestone rise out from beneath the chief masses of such 

 flysch, and are seen, at the same time, to be strictly united with 

 them. 



I have already stated that in Savoy, the only passage from the 

 chalk upwards with which I am acquainted, shows a gradual change 

 in the colour and texture of the rocks from the white limestone with 

 inocerami into the brown sandy nummulitic rock ; there being there, 

 as far as I could see, but one band charged withnummulites. Again, 

 in the section near Sewen, as we have seen, there is an apparent passage 

 between the uppermost beds of the inoceramus rock and the nummu- 

 litic strata above them. 



In the en\arons of Einsiedeln, however, the thickness of the lower 

 portion of the nummulitic group increases, and in subsequent pages 

 it will be shown how such development becomes still more striking 

 in the canton of Appenzell, and in the Bavarian Alps. 



The Schwendberg to the west of Einsiedeln consists of several but- 

 tresses of hard brownish nummulitic limestone dipping south (fig. 13). 



* I need not repeat the mineral description of the flysch, except where it offers 

 some new features. The generic word applies to t?ie group associated with and 

 overlying the nummulitic rocks, which is chiefly composed of thin-bedded, impure, 

 dark grey limestone with white veins, schists, both argillaceous and calcareous, 

 marls, micaceous sandstones, sometimes green-grained, but more frequently di- 

 versified by small black grains, with fucoids and a few casts of shells and fishes' 

 teeth in its lower parts. 



