﻿Vol. 64.] STRUCTURE OF THE TAENTHAL MASS. 601 



translation, but it does not appear that the fossils here are more 

 deformed than those from the Lias of Southern Tyrol, where there is 

 no question about the rocks being in their original site. But the 

 conspicuous mechanical shearing of the calcareous rocks just above 

 the bedded limestones, as also the strong folding and crushing 

 in the region of the dolomite-breccia, may and probably has been 

 acquired during movement. 



Original or (Ecogenous Characters of Rocks 

 of the Upper Zone. 



The topmost layer of quartzite and other altered schists and the 

 serpentine bear many characters vt^hich must have been acquired 

 before any movement of translation began. 



The parallel arrangement of the minute j)lates of chlorite in the 

 quartzitic rocks (which also contain tourmaline) is a feature that 

 must have been acquired at deep levels, under conditions similar to 

 those determining the structure of the older crystalline phyllites. 



The tourmaline is in the form of single, uudistorted, minute rods, 

 bounded by faces of the prism and often showing a terminal 

 pyramid — characters which prove it to be the most recent addition 

 to the minerals composing the quartzitic rock. 



The close vicinity of rocks, presently to be described, which have 

 been modified by contact with the serpentine, suggests that the 

 tourmaline may bo a contact-mineral. The serpentine, however, 

 does not contain tourmaline. If not a contact-mineral, the tour- 

 maline must be older than the serpentine-intrusion. In either 

 case the tourmaline, the youngest product, was formed before the 

 rock-mass left its original site. 



Serpentine. 



The association of green schists with serpentine in several 

 distinct occurrences (Mieselkopf, Matrei) has been noted by 

 previous observers, as well as the occurrence of talc and magnesian 

 minerals in the schists adjoining the serpentine.-^ 



The igneous intrusion appears to have commenced at a time 

 when the rocks were still under the influence of causes producing 

 foliation. Hecrystallization under stress is indicated by the for- 

 mation of talc in the schists, by the presence of sheafy amphibole 

 in parts of the serpentine-mass near the contacts. 



That violent movements were in progress during the period of 

 activity covered by the serpentine-intrusion is shown by the mode 

 of injection of the serpentine in the ophicalcite, and by the 

 numerous detached masses of altered calcareous rock found em- 

 bedded in the serpentine at all levels up to the summits of the 

 Rockner and the Little Rockner. Among these torn-off fragments 



^ See J. Blaas, * TJeber Serpentin & Schiefer aus dem Brennergebiete ' Nova 

 Acta Leop.-Carol. Akad. der Naturforscher, vol. Ixiv (1894) no. 1. 



