20 ROYAL SOCIETY OF CANADA 



separated from the fossilift-rous sedinienls and regarded as pre-Cambrian, 

 while the fossiliferous portion was divided into several horizons, of which 

 the Levis was regarded as the upper member, and considered as the equi- 

 valent of the Calcifercus with a possible upward extension into the 

 Chazy or even the lower Trenton, as seen in the rocks of the city of 

 Quebec, while the Sillery and Lauzou divisions were assigned to the 

 horizon of the Potsdam sandstone in part. Other portions of these rocks, 

 separable from the beds near Quebec by a marked line of unconformity, 

 were regarded as properly belonging to the Cambrian system, portions of 

 which may extend down to the lowest member of that system, which may, 

 in Canada and northern New York, be regarded as fixed by the 

 Olenellus zone. This portion, beneath the upper Sillery, in 1863 was 

 referred to the downward extension of the Potsdam group, which was 

 about this date enlarged from a mere formation like the Potsdam sand- 

 si one, and made to include all between the Calciferous and the top of 

 the Iluronian. 



In the middle Silurian the new term Anticosti group was introduced 

 to include a great series of strata on the Island of Anticosti, which had 

 been studied by Eichardson in 1857, and which was found to embrace 

 the Niagara, Clinton and Medina formations, while the nomenclature 

 was still further added to by the employment of the term Guelph, which 

 was held to denote the upper member of this system. 



The upper Silurian was restricted to two formations only, viz., the 

 Onondaga and the Lower Helderberg, while the Devonian comprised the 

 usual series of formations found in the New York scale. In addition, 

 however, a new division was instituted, known as the Gaspé series, which 

 comprised a great thickness of limestones, sandstones and shales of some- 

 what uncertain horizon, but which were evidently closely related to the 

 recognized Devonian and L^pper Silurian. The similarity of some of 

 these beds in Gaspé to the Chemung and Portage divisions of Xew 

 York was pointed out by Logan as early as 1844, while the resemblance 

 of tlie lower or calcareous portion to the rocks known as Lower Helder- 

 berg, was also noted. The only member of the Carboniferous series 

 found in Quebec was styled the Bonaventure formation, which is held to 

 directly underlie the middle Carboniferous of New Brunswick, loiown 

 now generally by the name Millstone-grit. 



The great area of slates and limestones found in eastern Quebec, 

 between the Sutton anticline and the boundary of the state of Maine was 

 also, early in the history of the Geological Survey, regarded as largely 

 composed of strata of Silurian and Devonian age, the equivalent or the 

 extension of the Gaspé series. This area has recently been carefully 

 studied, and the formations in that part of the province were found to 



