^^1- 55'] TORSIOX-STRUCTURE OF THE DOLOMITES. 613 



y. Sett Sass and Pralongia. 



The Sett-Sass and Pralongia area a companion to 

 the Sella Syncline. — The Dolomite-mountain of Sett Sass, 

 together with the meadows of Pralongia and Stuores, form a 

 broken-up synclinal area on the southern side of the Langs-da-Fiir 

 Anticline and on the northern side of the Buchenstein Anticline. 

 The diagonal buckle of the Campolungo Pass extends from the Groden 

 Pass to the Buchenstein Anticline, and separates the Sett Sass and 

 Pralongia Syncline from the companion syncline of Sella. 



On the western side of the diagonal buckle three parallel faults 

 have already been traced in a north-north-easterly and south-south- 

 westerly direction, all having downthrow to the west, and therefore 

 lowering continuously younger rocks towards the central depression 

 of the Sella Massive (pp. 590 & 604). My earlier work showed that 

 the Pralongia ridge was cut by faults with downthrow to the east, 

 that is, towards Sett Sass ; only one fault was traced on the west 

 side of the Pralongia ridge with downthrow to the west.^ 



Eastern flexure - fault of the Campolungo - Pass 

 Anticline. — The subsequent examination of the Buchenstein 

 Valley has disclosed the southerly continuation of these cross- faults 

 penetrating the Pralongia ridge. The diagonal fault between 

 Pralongia and the Euones slopes is parallel with the Campolungo 

 and Pian-de-Sass Faults. It continues with the same north-north- 

 easterly and south-south-westerly direction through the buckled-up 

 Wengen rocks of the Cherz and Campolungo slopes. It separates 

 two general strike-systems in the rocks of Cherz Hill, the fault- 

 block on the west side having a north-easterly and south-westerly 

 strike and dip to north-west, the other on the east side of the fault 

 having a north-westerly and south-easterly strike and dip towards 

 the north-east. The fault maybe said to cut off the east-and-west 

 Yarda overthrusts on its east side from the Muschelkalk, augite- 

 porphyrite, and Wengen rocks composing the diagonal fault-block 

 of the Campolungo Pass. This fault passes through the steep flexure 

 of the rocks from the diagonal arch of the Campolungo Pass towards 

 the Selvaza and Ruones hollows on the east side. 



The oblique torsion-faults which slice the Yarda overthrusts round 

 the south-west of Cherz Hill meet the north-north-east and south- 

 south-west Campolungo Fault. It is impossible to trace these oblique 

 torsion-faults northward through the Wengen rocks of Cherz Hill, 

 as these are largely grass-grown. But it may be noted that a con- 

 tinuation in that direction would mean a general convergence of the 

 fault-lines towards the Selvaza hollow. All the exposures of Wengen 

 strata which can be found on the Selvaza slopes show considerable 

 contortions in the rocks, and prove strong compression. 



These features indicate a radiating bundle of small oblique torsion- 

 faults through the curved overthrusts round the south-west of Cherz 

 Hill. The correlation of these torsion-fault curves and radii with the 



^ Quart. Journ. Geol. Soc. vol. xlix (1893) p. 18 & map A. 



