628 MISS M. M. OGILVIE [MRS. GORDON] ON THE [Aug. 1 899, 



arranged with regard to the Yiezzena and Predazzo area. They 

 pass from it in a south-south-westerly and north-north-easterly 

 direction to Buchenstein, more north-and-sonth at Eodella and the 

 Sella Pass, and more south-south-east and north-north-west towards 

 Rosengarten, the varying direction agreeing with the reciprocating 

 character of torsion- faults. 



This arrangement shows the radiating faults to have 

 been initiated in association with eruptive outbreaks 

 in the area next the resisting mass of Permian eruptive rock. 

 Also, they clearly mark a relatively late phase in the torsion, since 

 they frequently cut less curved faults belonging to the Asta system, 

 although in other cases they pass into them and form a Judicarian- 

 Asta curve (see footnote, p. 577). Such a curve, however, is no 

 simple tectonic line, but the result of cross-folding. 



Torsional eruptivity. — Upon the basis of the observations 

 detailed above, we have to distinguish different phases in the pro- 

 tracted history of torsion, marked by progressive phases in the 

 collateral history of eruptivity. 



The ' middle limb ' between the anticlines and synclines of the 

 earlier east-and-west Alps presented a series of septal lines of crust- 

 weakness, to which were added in the Judicarian district north-and- 

 south lines of crust-weakness attendant upon the earlier Permian 

 intrusive mass. These were the special lines which determined 

 the form of the later peri- Adriatic depression. 



The history of torsion starts with oblique fracture of the old 

 septal lines along correlated diagonal lines (see p. 571). Escape 

 of the underlying molten rock along the old fold-septa, inrush 

 towards and spreading out of the underlying rock within the 

 torsion-buckles, which took shape as torsion proceeded, and injection 

 of dyke-material into torsion-faults in course of formation may 

 be regarded as progressive stages of torsional eruptivity during 

 mountain-upheaval. Eruptivity is a necessary part of the regional 

 dynamic phenomena (see p. 611). The later phases of decadence 

 have reference more especially to the synclinal torsion-basins. The 

 demarcation of a torsion-basin, the heaping-up of the strata 

 peripherally, and their attenuation centrally are results of 

 torsion-movement. And the local escape of underlying rock at the 

 rim or within attenuated central areas denotes a further stage of 

 torsion. 



Thus torsional eruptive activity may be said to have marked 

 time in a history of Alpine movement, which extends from the later 

 Cretaceous to the present age. 



Characteristic stratigraphical features in the Judi- 

 carian-Asta district. — The geology of the Adige Basin and 

 the Cima d'Asta area has been made known in a series of able 

 works by Suess, Lepsius, Yacek, Bittner, and other well-known 

 Austrian geologists. A brilliant chapter by Suess, in his 'Antlitz 

 der Erde,' summarizes the facts as known in 1885, and leads the 

 reader clearly and carefully through the intricacies of the Adriatic 

 Subsidence. Cima d'Asta was described by Suess as a Horst, 

 since the investigations of Mojsisovics had pointed out the repeated 



