GEOLOGY OF TTIE CONNECTICUT VALLEY DISTRICT. 463 



prevails at present too much of a tendency to attribute extraordinary influences to met- 

 amorphic agencies. So soon as tlie true limits and effects of metamorphism are 

 recognized, it will probably be acknowledged that whatever view may be entertained 

 as to their origin, the schistose rocks above referred to underlie the Silurian and all 

 7in altered or j/ietatjwrphosed fossiliferous strata.''^'' 



The Huronian of Quebec. 



In consequence of the changes of opinion respecting these rocks in the more west- 

 ern area, or that represented upon Plate I and mentioned upon page 12, it is difficult 

 to estimate the proper succession and thickness of the several members. Sir W. E. 

 Logan has described them under the general name of Quebec group, with three divi- 

 sions. He has grouped together a large series of fossiliferous Cambrian and metamor- 

 phic rocks, assuming that the one was the equivalent of the other. I have endeavored 

 to separate the fossiliferous from the metamorphic portions, with the assistance of Dr. 

 T. Sterry Hunt, upon Plate I, though it may not be so easy to decide between the 

 bands as belonging to the one or the other series. On page 12, I have stated that the 

 western band of Huronian extends to the end of the peninsula of Gaspe. That is an 

 error. After eliminating the fossiliferous portion, the metamorphic area is found to 

 reach only about as far east as the city of Quebec, and it is properly represented upon 

 the map, and there is also a small isolated area near the end of the peninsula. The 

 line of the Bayer and Stanbridge anticlinal is the proper division between them. 



Logan's classification, as derived from the report upon the geology of Canada for 

 1866, is the following: The lower or Levis series consists of limestone, black shales, 

 gray shales, dolomites, and conglomerates, amounting to 6,145 feet for the maximum 

 thickness. This carries numerous graptolites and other fossils distinctly belonging 

 to the region of the Calciferous and Chazy. 



The middle or Lauzon division is marked by a predominance of green, red, and 

 purplish shales, with thickness ranging from 100 to 6000 feet. Two brachiopods occur 

 in it. The metamorphic portion is bounded by two magnesian bands, dolomite, soap- 

 stone, or serpentine. Logan supposes the soapstone and serpentine are altered dolo- 

 mites. These two bands are accompanied by beds of metallic ores, particularly of 

 copper. Of the three synclinal areas, the most western is regarded as unaltered, and 

 the two eastern as true Huronian. The second synclinal carries chlorite and epidote, 

 which are wanting in the first or Paleozoic basin. Other rocks are talcoid schists, 

 greenish micaceous sandstone, nacreous slates, etc. The third synclinal is like the 

 second lying east of the Green Mountain range. The upper or Sillery division, unal- 

 tered, consists of greenish (slightly calcareous) sandstone, passing into fine conglom- 

 erates, about 2000 feet thick. The metamorphic portions are chiefly epidotic and 

 chloritic schists and quartzites. 



From this series, as proposed by Logan, we must eliminate all the fossiliferous por- 

 tions, and invert the order. The fossils known to occur in the unaltered formations 

 agree to this reversal, and we find the Sillery and Lauzon groups correspond to the 



