566 MISS M. M. OGILYIE [mKS. GORDON] ON" THE [Aug. iSppy 



granite-grained masses round the Peri-Adriatic area of subsidence, 

 agreeing with Prof. Brogger that the granite- and monzonite-masses 

 and the liebenerite- dykes are younger than the Middle Triassic series ; 

 and stating that, ' in the present state of our knowledge, we cannot 

 possibly say at present whether they are to be regarded as Upper 

 Triassic, Jurassic, Cretaceous, or Tertiary.' He inclines, however, 

 to the view that they are of Lower Tertiary age. 



Conclusions arrived at in the present paper. — In the 

 present paper I propose to show that the results obtained during 

 my recent detailed survey of the Sella and Sett Sass district fully 

 establish the following conclusions : — 



(1) Faults and over faults are far more prevalent in the Dolomite-country 



than has hitherto been supposed. 



(2) The arrangement of these faults is typically a torsion-pheno- 



menon. 



(3) This phenomenon is the result of the superposition of a later upon an 



earlier strike of the rocks. 



(4) The later crust-movement was of Middle Tertiary age, and one with 



the movement which gave origin to the ' Judicarian-Asta' phenomena, 

 and more generally to the phenomena associated with the Oligocene- 

 Miocene upheaval of the Alps. 



(6) The youngest dykes and granitic masses are of this age, while the 

 geographical position of both is the natural effect of the crust-torsion 

 itself. 



(6) The phenomenon of crust- torsi on fully explains the special strati- 

 graphical features of the Dolomites enumerated above, namely, the 

 present isolation of the mountain-massives of dolomite-rock, the 

 irregular shearing of various horizons of lower rocks around the base 

 of the massives, the fanning-out of overthrust slices of the lower rocks 

 in the intervening passes and valleys between the massives, and the 

 presence of ' scoops ' of Jurassic and Cretaceous rocks within the 

 massives themselves. 



II. The Anticline op the Geoden Pass. 



Previous description of the Groden Pass area by 

 the Austrian Geological Survey. — The strata of Groden 

 Pass and Sella Mountain have been described in outline in the- 

 Survey carried out by E. von Mojsisovics ^ and his colleagues. But 

 as he recognizes in the Werigen and Cassian tufaceous, marly,, 

 and calcareous series at the base of the mountain-cliffs only the 

 equivalent in time of the dolomite-rock that chiefly forms the 

 cliffs, he calls the latter rock Wengen and Cassian ' coral-reef ' 

 dolomite, and maps it as if it thinned out all round the mountain into 

 the supposed ' heteropic ' facies of earthy deposits (see p. 562). 



This standpoint completely differs from the present author's, and 

 it would only obscure this paper to draw repeated comparisons 

 between the observations published in Mojsisovics's ' Dolomit-Eiffe ^ 

 in 1879, and those now made by me in very much greater detail* 



^ ' Die Dolomit-Riffe von Siid-Tirol u. Venetien,' 1879, chap, viii, p. 227. 



