210 The Ottawa Naturalist. 



The gneisses which are as a general rule intimately associated 

 with the limestone are quite different from those of the second class 

 they are almost all highly garnetiferous and frequently consist essentially 

 of garnet and sillimanite. Quartz and othoclase are present insubordi- 

 nate amount, some of them contain pyroxene, scapolite and other 

 minerals. These gneisses show no granulated structure, the minerals 

 constituting them have crystallized under the influence of the pressure 

 which has granulated the gneisses of class 2, and are not in any marked 

 manner deformed by it. 



These rocks are generally well banded; this structure being much 

 more pronounced than the foliation, and graphite, which does not 

 occur in the igneous granulated gneisses of class 2, is very frequently 

 present and often abundant. 



Complete analyses are furnished of four specimens of these gneisess 

 from various localities throughout the district under examination. Two 

 of these have the composition of ordinary roofing slate; a third, highly 

 quartzose, bears a very striking resemblance in composition to the 

 more silicious bands so often found in slate quarries. The fourth of 

 these gneisses (from Rawdon) differs entirely from the others and if it 

 is an altered sediment it is one which has suffered very little leaching 

 during deposition and must have been of the nature of a tufaceous 

 deposit or one formed from the rapid disintegration of an igneous rock 

 having the composition of a basic trachyte or syenite. 



The gneiss of Trembling Mountain like many others including 

 some in the Grenville series has undoubtedly the composition of an 

 igneous rock being simply granite which has undergone deformation 

 by pressure. 



It is impossible in the brief space allotted to a review to even 



mention all of the important results obtained from these studies but a 



careful perusal is recommended to every worker, and sudent interested 



in the difficult problems of Archaean geology. 



A. E. B. 



Our Club has just received from the author a most interesting book 

 entitled " The History of Mount Mica of Maine, U. S. A. and Its Won- 

 derful Deposits of Matchless Tourmalines" by Augustus Choate Hamlin, 



