16 



THE ROYAL SOCIETY OF CANADA 



General Data 



For the purpose of general description the border zone adjoining 

 the Laurentian highlands in the lower Ottawa and St. Lawrence 

 valleys may be conveniently divided into 4 subdivisions: (1) the 

 region extending along the southern border of the Laurentian highlands 

 between Montreal and Quebec; (2) the lowland area including the 

 eastern part of southeastern Ontario and the adjacent territory in 

 Quebec and New York State; (3) the irregular depression forming 

 the lower Ottawa valley to the west of Ottawa, and, (4) the region 

 lying between the Laurentian highlands and Lake Ontario to the west 

 of Kingston. 



Diagram showing the principal faults along which the Palaeozoic and older 

 formations occurring in the lower Ottawa valley have been displaced. 



In the first of these localities, the district lying north of the St. 

 Lawrence between Montreal and Quebec, the Palaeozoic formations as 

 shown on the published maps of the Geological Survey^ outcrop in 

 succession from north to south as continuous belts trending parallel to 

 the southern margin of the Laurentian plateau. In the district lying 

 north of Montreal and eastward as far as Three Rivers the complete 

 succession from the Potsdam sandstone to the Queenston shale is 

 represented but from the Three Rivers district eastward to Quebec 

 the lowermost formations are missing and the Trenton limestone 

 rests directly on the Pre-Cambrian. The regional dip of the Palaeozoic 

 strata in this border belt, according to the observations of Logan^ and 

 Ells^ is generally between one and three degrees towards the south and 



* Map of Canada, in atlas accompanying Geology of Canada, 1863. Three 

 Rivers Sheet, accompanying Part J, Vol. XI, Geol. Surv. Can., 1898. 



^ Geology of Canada, 1863, pp. 150 and 152-53. 



^ Geology of the Three Rivers Map-Sheet, Ann. Rep. Geol. Surv. Can., Vol. 

 XIV, 1901. 1898, Part J., pp. 14-15 



