MINERALS AND GEOLOGY OF CANADA. » 



Trenton formation is probably abont 700 or 750 feet in thickness ; the 

 Utica shales, somewhat under 100 feet ; and the Hudson River series, 

 between 700 and 800 feet. These formations are developed chiefly 

 along the shore of Lake Ontario, between Kingston and the central 

 part of Nelson township, west of Toronto ; and also on the shore of 

 Georgian Bay, between Cape Crocker and a spot a little south of the 

 outlet of the River Severn ; as well as throughout all the intervening 

 country : including within the Trenton area. Lake Simcoe, Balsam 

 Lake, Rice Lake, and other bodies of water. Kingston, Belleville, 

 Peterborough, Cobourg, Port Hope, Barrie and CoUingwood, are situ- 

 ated over the Trenton district ; Whitby and the country just west of 

 CoUingwood harbour, over the Utica formation ; and Toronto, Oak- 

 ville, Sydenham (Owen Sound,) and Meaford, over the Hudson River 

 strata. These various formations, as explained fully under their re- 

 spective descriptions on a former page, run also across the northern 

 part of the Manitoulin Islands. 



The Niagara or Anticosti group succeeds the Lower Silurian strata. 

 The Medina Formation (Map : No. 9), at its base, sweeps round by 

 Queenston, Hamilton, &c., below the great escarpment of that district, 

 and continuing its course, first towards the north and then towards 

 the north-west, comes out upon Georgian Bay near Cabot's Head, 

 forms the extreme base of that promontory, and runs, it is supposed, 

 in a narrow belt along the central part of the Manitoulin Isles. These 

 Medina strata consist chiefly of red marls, shales, and sandstones, 

 capped by a grey freestone, known as the "grey band." On Lake 

 Ontario, they exceed 600 feet in thickness, but diminish considerably 

 towards their north-western limits. The green and red shales of the 

 Clinton division (No. 10,) with their interstratified limestone beds, 

 appear above the grey band of the Medina formation proper ; and are 

 succeeded by the calcareous shales and limestones of the Niagara for- 

 mation, holding Pentamerus oblongus, fig. 213, amongst their other 

 fossils. The Niagara limestone (Map: No. 11) appears to represent in 

 the Middle Silurian strata, the great Trenton limestone of the Lower 

 series. Still higher in the scale, and farther to the west, follow suc- 

 cessively the Guelph dolomites (No. 12), the gypsiferous and fossil- 

 free strata of the Onondaga formation (No. 13), and the slightly de- 

 veloped Eurypterus beds of the Lower Helderberg group. These 

 close the Silurian series, The country between the upper part of the 

 Niagara RiVer and the north-eastern shores of Lake Huron, is occu- 



