396 



MR. A. V. JENNINGS ON THE 



[Aug. 1899, 



Tarnuzzer, and others in neighbouring districts ; but in the Davos 

 district there are, I believe, only two great bands of breccia, which 

 may be termed the ' crystalline ' and the ' polygenic." The former 

 consists only of crystalline fragments, the latter of a varied 

 assortment more specially described below. 



Pig. 2. — Specimen of '-polygenic breccia ' (reproduced from a 

 photography -^ nat. size). 



V = Eed Verrucano. 



D = Grey Hauptdulomit. 



S = Grreen Schist. 



T = Yellowish Lower Triassic 

 limestone. 



The crystalline breccia occurs along the Upper Parsenn 

 slopes, between the serpentine and the red rocks and dolomite of the 

 Cotschna. Its crystalline character is evident, but it may be easily 

 mapped as gneiss and schists, because it is often only the weathered 

 surface which reveals its brecciated character. On Theobald's map 

 it thus appears simply as gneiss ; and in the accompanying memoir 

 the main axis of the Parsenn ridge is referred to merely as ' gneiss.' 

 The railway-cutting at Laret Station offers an excellent exposure, 

 showing both the character of fresh fractures and the appearance 



