OF CENTRAL CANADA PART V. 315 



best display is at the north end of Knowlton Lake, where the Potsdam 

 strata form a high cliff composed of thin-bedded, more or less ferru- 

 ginous sandstones of a red and brownish-green colour. A sandstone 

 bed of the same formation, available as a material for furnace hearths? 

 occurs at the Frontenac mining location in Loughborough township, 

 about 12 miles north of Kingston. 



The Calciferous and Chazy Formations which intervene, in the Pa- 

 laeozoic area of the lower Ottawa, between the Potsdam and the Tren- 

 ton formations, have not been recognized within the present district. 



The Trenton for Black River and Trenton) Formation is repre- 

 sented chiefly by dark-grey thick-bedded limestones overlaid by lime- 

 stone shales. The upper beds are in places exceedingly fossiliferous, 

 and most of the lower beds yield excellent building stones. One of 

 these latter beds is capable of employment, for the greater part, as a 

 lithographic stone. It forms a continuous band, running north-west 

 from the vicinity of Kingston, through Marmora, etc., to Georgian 

 Bay. The thickness of the formation in this district averages about 

 700 or 750 feet. The northern boundary runs from the St. Lawrence 

 a little east of Kingston, through North Hastings, Peterborough, 

 South Victoria, Ontario, and Simcoe, to near the mouth of the River 

 Severn on Georgian Bay a chain of small lakes indicating its course 

 throughout the greater part of the distance. North of these lakes, 

 gneissoid Laurentiaii rocks occur in highly tilted beds, whilst the 

 Trenton (or Black River) strata, on the south, occupy a nearly hori- 

 zontal position. The southern boundary of the formation constitutes 

 the coast of Lake Ontario from Kingston to the neighbourhood of 

 Newcastle a few miles west of Port Hope. From that point the 

 formation turns towards the north-west, and passing across Dur- 

 ham, Ontario, and Simcoe, comes out on Nottawasaga Bay, west of 

 Colling wood. The intermediate country, however is very thickly 

 overlaid in most places by Drift and superficial deposits. Some of 

 the more frequently occurring fossils comprise : Lithophycus Ottawa- 

 ensis (fig. Ill); Stromatopora rugosa (fig. 127) ; Monticulipora (or 

 Stenopora) fibrosa (fig. 136); Columnar ia alveolata (fig. 142); 

 Petraia corniculum (fig. 148) ; Glyptocrinus decadactylus (fig. 154) ; 

 Leperditia Canadensis (fig. 165); Asaphus platycephalus (fig. 168) ; 

 Trinucleus concentricus (fig. 172) ; Cheirurus pleurexantheinus (fig. 

 173); Calymene Blumenbachii (fig. 178); Strophomena alternata 



