624 MISS M. M. OGILVIE [mES. GORDON] ON THE [Aug. 1 899, 



Laiig-Kofl group. Similar^, Monte Sief is left west of the Sasso- 

 di-Stria faults, as a torsion-block of older strata in close proximity 

 to the Sett-Sass basin. 



Lake Alleghe. — Lake Alleghe seems to be an area of con- 

 vergence for several diagonal faults. The north-north-westeriy and 

 south-south-easterly fault from Corvara to Contrin continues down 

 the Cordevole Yalley towards Caprile and Lake Alleghe. The faults 

 on both sides of the diagonal arch of Sasso di Stria, as well as a 

 diagonal fault west of the next diagonal arch of Travernenzes and 

 jSTuvolau, all tend to converge if continued southward towards Lake 

 Alleghe. Hence the lake seems to be a chief centre of torsion- 

 radii in the district (see fig. 22, p. 630). 



The Cortina area. — I should wish here to indicate briefly how 

 the laws of torsion may be also applied to the stratigraphy of two 

 other localities which I examined and mapped geologically.-^ 



The Pakarego Valley represents an older east-and-west anticline 

 which has been twisted round the southern arc of the Tofana group. 

 The fault-curves hade northward and pass obliquely north-westward 

 through Tra i Sassi and north- eastward round the Cortina meadows. 

 The chief diagonal arch which has crossed the anticline is that of 

 the Ampezzo Valley. A sharp curvature of the strike from the 

 Ealzarego to the Ampezzo Valley is again the seat of intersection of 

 normal and reversed faults by a group of radiating faults. These 

 faults radiate southward and eastward from the Tofana massive 

 at Verviers, Lake Majorera, and Eomerlo. The Tofana bundle of 

 fault-radii is therefore, in its south-easterly direction, compensatory 

 to the Centurinus bundle north of Pralongia, where the fault-radii 

 are directed towards the west and south-west. 



Diirrenstein Mountain. — The present author's map of 

 Dlirrenstein Mountain^ exhibits a complicated system of faults. 

 The leading fault-curves describe a narrow northern fold-arc round 

 the mountain, and hade southward. 



The Diirrenstein Massive denotes cross-buckling superposed upon 

 an older east-and-west trough. The east-and-west anticline on the 

 north has been penetrated by a series of reversed faults, slicing cbiefly 

 Muschelkalk and AVengen strata. A steep northward flexure at the 

 Sari Kofele has been cut by a normal fault letting down the Cassian 

 and Schlern-Dolomite strata of Diirrenstein. The latter are cut 

 into several shear-^ices in the part next Sari Kofele, so that the 

 section from the anticlinal arch to the synclinal basin would closely 

 resemble that of the equally compressed area of Col di Lana, Monte 

 Sief, and Sett Sass. The central portion of the Diirrenstein Massive 

 represents part of the original trough, round which older strata 

 have been twined ; the iutbrow is on Platz meadow. The general 

 strike is north-west to south-east, in the central part of the area, 

 but in the torsion-arcs north of it the strike veers round from 

 north-east and south-west to north-west and south-east. 



Two features deserve special attention in this area : one is that 



1 Quart. Journ. Geol. Soc. vol. xlix (1893) map B, pp. 28-32 & pp. 68-69. 

 ^ Ibid, map C, facing p. 32. 



