[amr] GEOLOGY OF SOME CITIES IN EASTERN CANADA 131 
ORDOVICIAN OR CAMBRO-SILURIAN SYSTEM. 
Under this system are classed the following geological formations 
in descending order :— 
nm 
.—Lorraine formation. 
6.—Utica formation. 
5.—Trenton formation. 
4.—Bird’s Eye and Black River formation. 
3.—Chazy formation. 
2.—Calciferous formation. 
1.—Potsdam formation. 
These seven distinct geological formations in their greatest develop- 
ment form a covering of palæozoic sediments over the underlying 
eroded Archean floor of between 1,200 and 1,300 feet in thickness. 
The Potsdam formation consisting of light yellow and red sand- 
stones and conglomerates, often characterized by the presence of tracks 
and trails of marine animals and a few types of the Second Fauna of 
Barrande (Post-Primordial) is best exposed in the vicinity of Bucking- 
ham Basin, at Angers, at Papineauville, skirting the base of the Lauren- 
tide Hills, also in the township of March, at Bishop’s quarries and else- 
where on the Ontario side. The artesian well just south of Ottawa city 
reached this formation at a depth of 1,005 feet, but was not penetrated 
throughout its entire thickness. The Potsdam affords excellent blocks for 
building purposes, for pavement, and its siliceous constituents make it 
useful in the iron industry as well as for the manufacture of glass. 
The Calciferous formation consists for the most part of magnesian 
limestones, usually cavernous, the latter often covered or lined with 
numerous quartz crystals. These limestones pass downwards into 
arenaceous sediments. In certain localities pseudo-conglomerates of a 
concretionary nature are prevalent. The fossil organic remains en- 
tombed in the Calciferous formation about Ottawa indicate a typical 
lower Ordovician fauna, and the best localities where this formation 
can be studied to advantage in this district are :—Rockland, in the town- 
ship of Gloucester; at Black Rapids; and in the township of Marl- 
borough, at Lake Constance, on the Ontario side, and at the Queen’s 
Park, Lake DesChénes, above Aylmer ; and in Templeton on the north 
or Quebec side of the Ottawa. 
The Chazy formation is divisible into three series of strata, the 
lowest of which consists of arenaceous shales, and sandstones oftimes 
calcareous, the intermediate series of variously coloured bands of shale 
R Sec. IV., 1900. 7. 
