626 MISS M. M. OGILVIE [mES. GOEDON] ON THE [Aug. 1 899, 



mountain -group as the corresponding syncline of the northern wing, 

 and this sj^ncline is marked by attenuation of the strata towards 

 the Puez Alp, where Jurassic and Cretaceous rocks are present. 

 The anticline of the Buchenstein Yalley has on the south and south- 

 east Sella and Sett Sass, as the corresponding syncline of the 

 northern wing. JBoth these synclines are characterized by a similar 

 attenuation of the rocks towards an inner depression, containing 

 inthrown high horizons of Upper Triassic or even Jurassic rock. 



The relations would be extremely simple, had they not been 

 complicated by the diagonal torsion-folds. The diagonal anticline 

 of Enneberg is that which forms the Abtey Valley, and is recog- 

 nized again in the Corvara, Euones, Campolungo, and Cherz-Hill 

 buckle crossing from the Groden-Pass Anticline to that of the 

 Buchenstein Valley (see map, PI, XL). 



It is the combination of longitudinal and diagonal 

 buckling which has marked out the separate synclinal 

 areas in Enneberg; and this combination has been 

 explained fully as the result of the curving torsion 

 fold-arcs formed in diagonally opposite senses. 

 Those of any one torsion-system combine wit.h those 

 of adjacent torsion-systems to produce a w^horl- 

 shaped arrangement of anticlines round separate 

 synclinal areas. 



Anticlines have been twisted round synclines, and the rocks in 

 the synclines have themselves been twisted and distorted, buckled 

 up and depressed, overthrust and faulted normally, cross-faulted 

 and cleaved, to an extent that has not hitherto been realized. 



Tiers-Duron torsion- system. — We may apply the prin- 

 ciples of torsion throughout the Dolomites. And, first, to recur 

 .to the continuous east-and-west ridge from Mahlknecht to Col 

 di Lana, which I replaced in imagination above (p. 562), The 

 ridge as there reconstituted was supposed to have been once an 

 actual line of Middle Triassic flexure and lava-outflow, limiting an 

 ancient submarine terrace to the north of a wide sea- basin. The 

 same line may be traced westward through Botzen and eastward 

 towards Pieve di Cadore, Tolmezzo, Raibl, etc. (see fig. 22, p. 630). 



The continuity of the ridge was described as having been broken 

 in the Tertiary period of Alpine upheaval by the influence of the 

 torsion-forces demonstrated in the case of the Buchenstein part of 

 the ridge (§ III, pp. 587-590). 



In the area immediately west of the Buchenstein Anticline I 

 would distinguish a torsion-system extending through the broken 

 anticlines of the Tiers and Duron Valleys, with the Schlern and 

 Piatt Kofl Mountains as northern synclines, and Eosengarten as 

 the southern syncline. Tbe cross-buckle of Mahlknecht separates 

 the adjacent synclines of Schlern and Piatt Kofl, much as the Cam- 

 polungo buckle separates the adjacent synclines of Sella and Sett 

 Sass. The anticlinal axis of the Tiers-Duron system is set west- 

 south-west and east-north-east. The Bodella portion has been 

 twisted northward, and the Tiers portion southward. 



