"^^^' 55-] TORSIO]!f-STRUCTtrKE OF THE DOLOMITES. 563 



■centurj', the subject has gradually assumed a new aspect, and a 

 tendency has been developed among geologists to regard these 

 strange forms as of secondary origin — the results of the partial 

 denudation of a mountain-region built up of normal rock-formations, 

 which had been affected by excessive crust-movement. For example, 

 it will be in the recollection of some of those who attended the 

 Geological Section of the British Association at Edinburgh in 1892 

 that this point of view was taken by Prof. Lap worth, who, carrying 

 out the principles dwelt upon in his Address,^ urged, during one of 

 the discussions, that the Dolomite -country was a typical region of 

 cross-foldiog and faulting, and that its so-called reefs and other 

 characteristic features were of secondary and tectonic origin due to 

 Tertiary crust-movements, with which movements the injected 

 bosses and sills (including even those of Predazzo) were probably 

 connected. 



Passing, therefore, to the tectonic side of the Dolomite question, 

 it may here be briefly indicated that the chief structural conclusions 

 worked out in my previous papers were as follows : — 



(7) Some of the curious stratigraphical appearances round the base of the 



so-called ' reefs,' synonymous with the mountain-masses, are due to 

 faults. 



(8) A large proportion of these faults have inclined fault-planes, upon 



some of which overthrust, and upon others downthrow, has taken 

 place. 



(9) These inclined faults have been cut locally by subsequent transverse 



faults, causing horizontal displacement. 



(10) Igneous rocks occur as injected sheets and dykes in some of the many 



anticlinal faults. 



(11) The above-described system of overthrusting and cross-faulting in 



Enneberg and Ampezzo corresponds in all its characteristic features 

 with the Judicarian-Asta system of faults demonstrated in the various 

 parts of Southern Tyrol by Suess, Vacek, Benecke, Bittner, and 

 Hcernes. ' The same long flexures passing locally into faults occur, 

 the same types of overthrusting, and the same swinging round of the 

 Judicarian dislocations into those of the Asta series.' In fine, the 

 areas mapped by the present author were characterized by a group of 

 stratigraphical features in complete harmony with features previously 

 identified in neighbouring areas ; and these dominant stratigraphical 

 features were quite independent of the Middle Triassic facies within 

 region of the Dolomites. 

 3(12) With regai'd to the geological age of these disturbances, the writer 

 demonstrated the broken course of one main longitudinal fault or 

 flexure of Triassic age; emphasized the presence of a number of 

 parallel longitudinal faults, all containing eruptive injections, and all 

 giving evidence that they had been important planes of movement 

 since Mesozoic times, concluding that the predominating system of 

 faults identified by her with the Judicarian-Asta system generally, 

 must be of Tertiary age : these ' in some places coincided with, or 

 crossed at varying angles, lines of Triassic disturbance,' a conspicuous 

 example being the famous ' eruptive fault ' of Monzoni-Fassa 

 associated with the igneous injections of the neighbourhood of 

 Predazzo. 



The igneous dykes penetrate nowhere higher than Upper Triassic 

 Tock in the Dolomites, and even as late as 1894 I was unable 



- Brit. Assoc. Rep. 1892 (Edinburgh) pp. 699 et seqq. 



2o2 



