144 ROYAL SOCIETY OF CANADA 



fragments of the underlying sandstone, in a ealcareo-arenaceous fossilif- 

 erous matrix ; some of the inclosed masses being nine feet in diameter. 

 Xear by are seen the lluronian sandstone strata, great cracks and worn 

 fissures which are filled with the fossiliferous cement." ' 



The limestones Avhich make up the bulk of this outlier are mostly 

 buff or cream-coloured with thin interstratified shales. Some of the beds 

 are hard and cherty, resembling lithographic stone, and the whole series 

 contains an abundance of corals with other fossils which clearly indicate 

 their horizon. 



The thickness as expo.sed in the sections is stated to be about one 

 hundred and tift}' feet, and this is probably increased by the series of beds 

 near the centre of the deposit, so that the whole thickness is estimated 

 bj' Mr. Barlow as not more than three hundred feet. 



Jn regard to the several fossiliferous outliers which occur at often 

 widely separated points throughout the basin of the Ottawa, it may be 

 said that in none of these can the same succession of formations as we 

 have just described be observed. Some are represented by but one, the 

 others having been presumably removed by denudation of the overlj'ing 

 strata. 



On the north side of the Ottawa Eiver, with the exception of the 

 small fringe which is found between the Laurentian hills and the river 

 itself, only two, or at most three, distinct areas of small size have yet been 

 recognized. The most easterly of these is the small outlier of Calciferous 

 strata lying to the east of the North River about seven miles northwest 

 of St. Jerome to the north of Montreal, where characteristic fossils of this 

 formation are found. Further west at the village of Lachute, a hill of 

 Potsdam sandstone occurs just east of the village with an exposed thick- 

 ness of about forty feet, and is directly overlaid by the Calciferous, which 

 is seen in the bed of the North River at the crossing of the Canadian 

 Pacific railway ; but these outcrops ])resumab]y represent the northern 

 margin of the Ottawa and St. Lawrence basin. The succession of for- 

 mations seen in the city of Hull and thence to Aylmer and for several 

 miles beyond, representing rocks of Calciferous, Chazy, Black River and 

 Trenton age, also belong to the same basin, the northern margin of 

 which is seen in thin strata of the Calciferous and Chazy near the village 

 <»f (^uyon, as well as in a small margin of the former on the north side of 

 the river near the old village of Pontiac at the foot of the Chats Falls. 



The northern margin of the Arnprior and Sand Point outlier is «Iso 

 seen above the Chats, along the north shore of the Ottawa for several 

 miles, as well as in several islands in the river below Bristol ; Init on the 

 roads, a mile or so east of Portage du Fort, isolated outcrops of dolomitic 

 Calciferous strata occur which have been broken up and, in places, altered 

 b,y the action of certain intrusive masses of greenstone which have cut 



• Geology of Cumula, 1863, pp. 3:14-36. 



