Tol. 55-] 



GEOLOGY OF THE DAVOS DISTRICT. 



407 



The great serpentine-mass of the Todtalp, which rises from under 

 the crystallines of the Dorfiiberg, has already been studied as a rock- 

 formation, but there are some features in its relationship to neigh- 

 bouring strata that must now be referred to. Its upper limit (or 

 southern margin) appears, as we have seen, to be directly overlain 

 by crystalline schists or by white granite occurring in them ; but 

 there is evidence that this junction is due to an overthrust of the 

 crystalline rocks. 



Pig. 7. — The Cotschna-Arosa fold : rock-exposure east of the Parsenn- 

 Furka Pass, between the two streams which unite to form the Stutzbach, 



[The above figure is copied from a sketch made on the spot, and shows the 

 interbedding of the Red Shales (which in the near neighbourhood are 

 associated with radiolarian cherts) with the Lower Triassic limestone.] 



The lower margin presents still greater difficulty. On the 

 western side the dark edge of the Schwarzhorn serpentine is 

 sharply outlined against the dolomite and rauchwacke of the Weiss- 

 fluh, but the absence of change in the character of either rock near 

 the junction suggests again the idea of an overthrust or a fault. 

 The thinning of the limestone series at the Parsenn-Furka Pass, 

 together with the disappearance here of the rocks of the Parsenn 

 slope described below, all point to the same conclusion — that the 

 same movement from the south-east, which has obliterated the 

 serpentine in the Haupterthal, has pushed the Todtalp serpentine 

 over the mixed rocks, which on the Parsenn slope lie between it 

 and the Casanna dolomite. At the eastern end of the mass, by 



