Vol. 55.] 



TOESION-STEIJCTUEE OF THE DOLOMITES. 



60' 



them are radii to the western curve limiting the outcrop of the 

 Jurassic strata, a curve parallel with the torsion- curve round the 

 western periphery of the mountain (see PL XL). 



A diagonal buckle, directed north-north-east, extends from the 

 Boe summit towards the Eis See summit, and is composed of the 

 highest horizons of the Dachstein Series. The summit-buckle, 

 which is fractured lengthways, with downthrow to the west, is over- 

 thrust eastward and 



southward upon Fig. 19. — Diagram of torsion at the 



the main mass of Boe summit. 



Dachstein Dolomite 

 forming the eastern 

 part of Sella. 



The occurrence of 

 Jurassic strata west 

 of the summit- 

 buckle is highly 



significant. It is 



Eis See 



Summit. 



^''^■ 



demonstrative of a 

 central subsideuce- 

 area within the 

 wider subsidence- 

 area occupied by 

 the whole massive. 

 The highest strata 

 may be said to have 

 collapsed into the 

 space afforded cen- 

 trally as a result of 

 the outthrust and 

 overthrust of the 

 rocks of the massive 

 all round the peri- 

 phery. This phe- 

 nomenon confirms 

 the correctness of 

 the observations al- 

 ready detailed. The 

 Jurassic strata are, 



moreover, present in a trough directed north-north-east and south- 

 south-west, parallel with the leading diagonal buckles in the Sella 



area. 



The summit-buckle is parallel with the two buckles on the eastern 

 side which have been already discussed, namely, the diagonal 

 antichne exposed in Raibl and Schlern-Dolomite rocks north-north- 

 east and south-south-west through the mountain from the Piz ter- 

 race to the Bova Alp, and the diagonal anticline which runs across 

 the Campolungo Pass exposed in Wengen-Cassian strata. Both of 

 these lower anticlines, as well as the summit-buckle, are traversed 

 by diagonal faults, with downthrow to the west. 



J' 



[The general outline of the summit-buckle and over- 

 thrust is shown by strong broken lines. The 

 heavy arrows represent the evoiute movements of 

 the overlay, the dotted arrows represent the invo- 

 lute movements of the underlay.] 



/"= Radial faults. H.= Bamberg shelter-hut 

 (Alpine Club). 



