116 THE ROYAL SOCIETY OF CANADA 



St. John Group — Mostly gray slates, with gray flags in the middle 

 part, and dark gray slates in upper. 



Protolenus Fauna Lower Cambrian. 



Paradoxides " Lower Cambrian. 



Lingulella several species Middle Cambrian. 



Parabolina Fauna 



Peltura, etc. " LIpper Cambrian. 



Dictyonema " 



Tetragraptus Fauna 



Leptobolus " Lower Ordovician 



Parabolinella " 



The upper part of the Ordovician is not represented in this 

 region. 



Cambro-Silurian 



A portion of the St. John Group has already been referred to as 

 of Cambro-Silurian age. Under the same designation we may refer 

 to several other areas as to whose geological age and relations there 

 still exists much doubt. 



The most important of these are the great belts of slaty and 

 quartzose rocks .which traverse the central portions of the Province 

 through its entire extent, lying on either side of and more or less 

 penetrated by the great central granite batholiths, as represented in 

 the Survey Map. Prior to the issue of the latter, these rocks had been 

 regarded by all observers (Gesner, Dawson, Hind, Robb, etc) as older 

 than Silurian, being variously designated as Transition, Cambrian, 

 Lower Silurian and Quebec group, but the subsequent finding of 

 fossils of more recent age having shown that such reference did not 

 apply to the whole district thus represented, the name of Cambro- 

 Silurian was coined to overcome the difficulty. But the difficulty 

 still exists, for while strata have been found containing well preserved 

 fossils of Silurian or more recent origin, others have also been found 

 carrying equally well preserved Cambrian remains. The trouble is 

 to isolate these from each other and to map their separate distribution, 

 but as the districts in question are almost without settlements, thickly 

 forest-clad and with few exposures, progress in this direction is neces- 

 sarily slow. The rocks over the area in question are also thrown into 

 innumerable small folds, often of an intricate character, and even 

 fossiliferous beds may at times have become included between the 

 plications of older strata. This was at one time supposed to be the 



