^^^' 55*] TOKSION-STKUCTURE OF THE DOLOMITES. 571 



p. 568) may be generally described as a distorted anticline with 

 S-curvatures northward and southward, bent into the form of 

 ' knee-bends' (Mojsisovics) and penetrated by injected igneous rock 

 in the two opposite areas of the ' middle limbs' (Heim). 



Structure of the central part of the Groden Pass. — 

 The outcrops of the Pitzculatsch, Plon, and Yallbach Faults converge 

 towards the height of the Groden Pass. The strata on the Pass- 

 ridge are steeply contorted, bedded tuffs and lavas, tufaceous grits, 

 marls and shales composing the Wengen Series. Numerous dis- 

 locations penetrate these soft rocks. The major dislocation that 

 breaks the anticline is indicated by a line of blocks crossing the Pass- 

 ridge continuously from the convergence-area of intrusive rock on 

 the western side to an area on the eastern side where intrusive rock 

 reappears. It then proceeds in a west-south-westerly and east- 

 north-easterly direction towards Sass Songe, continuing therefore 

 the direction of the Pitzculatsch Fault. It forms, however, the 

 northern limit of the anticline on the eastern slopes of the Pass, 

 similar in position to the Vallbach Fault on the western slopes, 

 and, like it, is a normal fault with downthrow to the north, that is,. 

 towards the Tschampatsch and Sass Songe cliffs. 



Another fault branches from the same high level on the eastern 

 slopes, and continues the general east-and-west (slightly west-north- 

 west to east-south-east) direction of the Yallbach Fault. But 

 it corresponds with the Pitzculatsch Fault, in so far as it forms 

 the southern limit of the anticline on the eastern side of the Pass.. 

 The southern fault is here distinctly reversed, with overthrust to the 

 south (fig. 4, p. 572). 



The combination of a normal and a reversed fault hading in the 

 same direction is one which I have found to be a characteristic 

 feature in the stratigraphy of the district, and its effect is to leave 

 the outcrops of the downthrown strata on either side of the neutral- 

 izing faults practically at one and the same level (fig. 5, p. 572). 



The ' Euon ' Eock. — About midway down the eastern slopes of 

 the Pass near Euon a prominent mass of Mendola Dolomite com- 

 mands attention. This is a thick wedge caught in the midst 

 of a f-.ult-net of injected igneous rock, and the rock has been 

 cleaved, sheared, and mutilated to such a degree that it is difficult 

 to define any limit between the Mendola Dolomite and its burnt and 

 sheared representative, the so-called ' Buchenstein agglomerate.' 

 At the same time, small fragments of so-called ' Buchenstein banded 

 shales and limestones,' representing, on the palseontological evidence,. 

 merely altered Wengen calcareous bands, are caught up in the shear- 

 planes. One larger unaltered wedge of AYengen strata fills in the 

 chief rupture-fissure on the eastern side of a transverse fault- dyke. 

 This will be referred to later as the Euon Dyke. 



The whole complex is only a more striking case of the same- 

 general phenomena of dyke-injection associated with fault-shearing 

 as those that I have described at the forking of the Pitzculatsch 



