﻿Yol. 64.] STEUCTUEE OF THE TAENTHAL MASS. 603 



(3) An upper section, consisting of more or less altered quartzite- 

 schists, with calcareous schists, ophicalcite, and serpentine. This 

 section retains most of its original character and form, and has 

 undergone little mechanical disturbance since it left its '■ root.' 



This is summarized in the following synopsis : — 



r Serpentine. 

 Zone 3 \ Ophicalcite. 



I Tarnthal Quartzites, etc. 



[ Calcareous schists with green bands. 

 Zone 2 j Doloniitic breccia. 

 I Calcareous schists. 



y -, r Liassic limestone. 



z/ONB 1 I Principal dolomite (Ehsetic). 



The explanation of the structure now suggested is as follows : — 

 The distinct line of division between the bedded limestones and 

 the calcareous schists — that is, between Zones 1 & 2 — marks 

 approximately the lower limb of a long fold, the dolomitic breccia 

 being thus a repetition in a highly attenuated form of the principal 

 dolomite below. 



As regards the relations between Zones 2 & 3, the interpretation 

 is not so clear; the absence of any line of demarcation between 

 these two series of rocks, which have been affected in different 

 degrees by dynamic activity, gives rise to some difficulty. But the 

 hypotheses that present themselves are : — 



(a) The collective mass 2 & 3 is in inverted sequence, tbe ser- 

 pentine and green schists belonging to an older series normally and 

 immediately below the dolomite — the dolomitic breccia belonging 

 to the lower limb of a fold, the upper limb of which is marked by 

 an air-line above the serpentine. 



Or (b) The dolomitic breccia represents the whole of the principal 

 dolomite in a flattened fold, the nappe. The serpentine and 

 quartzites have been brought into their present position by a long 

 overthrust, the traineau ecraseur of Prof. Termier. The rela- 

 tion of 1 and 2 in this case is one of enforced conformity, instances 

 of which are known elsewhere. 



Q.J. G.S. No. 256. 



