274 DR. J. W. GREGORY ON THE WALDENSIAN [May 1 894, 



VIII. StJMMARY OF CONCLUSIONS. 



1. The Cottian Sequence consists of: — 



(a) A series of coarse-grained gneisses occurring along the line 

 of the Eastern Cottians ; for convenience of reference these 

 are called ' the Waldensian gneisses.' 



(b) A thick succession of schists which are gneissoid near the 

 junctions with the gneisses, are mica-schists at the hase, 

 and pass upward into calc-schists. 



(c) An extensive group of epidiorites, serpentines, etc. (the 

 ' pietre verdi ' of Gastaldi), which traverse the lower part 

 of b. 



(d) A series of fossiliferous beds ranging from the Carboniferous 

 upward. 



2. The Waldensian Gneisses. A description of their field- 



relations and microscopic structure is given, and it is con- 

 tended : — 



(a) That they occur as independent, isolated masses, and not as 

 a continuous band having a fixed geological horizon at the 

 base of the whole series. 



(b) That instead of being basal Laurentian rocks, overlain by 

 or faulted against the schists, they are a series of igneous 

 intrusive rocks ; this is demonstrated by 



i. The contact-metamorphism around them, both exo- 



morphic and endomorphic ; 

 ii. The occurrence of apophyses of gneiss and aplite from 



the gneiss into the schist ; 

 iii. The gneiss often containing large altered blocks of the 



schists, and being sometimes saturated with chloritic 



and amphibolic material absorbed during intrusion ; 

 iv. The transgressive nature of the junction between the 



two series ; 

 v. The failure of any of the igneous rocks, intrusive into 



the schists, to cut the gneiss ; 

 vi. The fact that the gneiss has not been affected by the 



earth-movements which have crushed and contorted the 



schists. 



3. The Paradiso Gneiss. The relations of this on one margin 



are also described, and it is shown that it agrees in all re- 

 spects with the Waldensian gneisses, except for 



(a) Its greater mass. 



(6) The possibility that it was in part intruded at an earlier 



date. 

 The evidence in this case is less complete. 



