[amr] SYNOPSIS OF THE GEOLOGY OF CANADA 201 
The Lawrencian Lowlands.—In this region we have the following 
descending series of fossiliferous Ordovician formations : 
7.—The Lorraine (sometimes called Hudson River). 
6.—The Utica. 
5.—The Trenton. 
4.—The Bird’s Eye and Black River. 
3.—The Chazy. 
2.—The Calciferous. 
1.—The Potsdam. 
These seven distinct formations follow one another in regular 
order, covering the irregular surfaces of the Archean north-west of the 
great fault of the province of Quebec, and in Ontario. The Potsdam 
consists for the most part of a yellowish white or dark brown or red 
sandstone, with occasional beds of conglomerate, from which the Protich- 
nites or tracks and trails of marine animals were obtained. No truly 
Cambrian species have as yet been recorded from the Potsdam sandstones 
of Canada, on the contrary, the fauna is eminently Ordovician and one 
of the “ Second fauna” of Barrande. The Calciferous is a magnesian 
limestone, often arenaceous, whilst the Chazy is characterized by arenace- 
ous limestones, shales and limestones. The Black River formation con- 
sists for the most part of limestones of a decided lithographic character 
in its lower half, and usually heavily bedded in its upper portion. This 
and the succeeding Trenton limestones, along with the upper Chazy, 
have afforded excellent building stone for some of the finest buildings 
erected in Ontario and Quebec. The Utica consists for the most part 
of black brittle shale, bituminous in character, with bands of impure, 
magnesian and bituminous limestones interstratified at the base, whilst 
the Lorraine formation consists of deep gray, brown, fine-grained mud- 
stones, and magnesian limestones. These formations are extensively 
developed in the neighbourhoods of Montreal, Ottawa and Quebec, and 
the uppermost four occur throughout eastern Ontario. 
The Interior Continental Plain—In Manitoba the Ordovician rocks 
are extensively developed, forming the main mass of rock occurring in 
the Winnipeg and Lake Manitoba regions. 
The greatest thickness of Ordovician strata in the province of On- 
tario is doubtless to be found in the vicinity of Toronto city. At 
Clarkson’s, eighteen miles west of Toronto, there occur some 1,457 feet of 
shales, limestones and arkose bands, the Lorraine, measuring 650 feet; 
the Utica, 150 feet; the Trenton, 500 feet; the Black River, 157 feet. 
Interior Continental Plain.—Both the Trenton and Lorraine forma- 
tions (which by some geologists are classed as Galena-Trenton and Hud- 
