196 A POPULAR EXPOSITION OF THE 
mettes Rapids on the Ottawa, is accompanied by numerous dark 
nodules consisting chiefly of phosphate of lime, and supposed to be 
coprolites. Bathyurus Angelini (fig. 166) is a trilobite belonging to 
this formation. It has been found in the townships of Huntley, 
Ramsay, Grenville, &c. 
The principal economic materials of the Chazy beds (exclusive of 
those from the altered rocks of the Eastern Townships as described 
under the Quebec Group, above: some of these rocks being probably 
of Chazy age) comprise—a dvlomitic limestone from the township of 
Nepean in Carleton county, yielding the well-known “ Hull cement ; ” 
grey, and grey-and-red fine-grained limestones, capable of employment 
as marble, from Caughnawaga, Montreal, the Lake of Two Moun- 
tains, St. Dominique, and St. Lin, in Canada Hast; a thin-bedded 
limestone, filled with rhynconella plena, and largely quarried for 
tombstones and table-tops, from L’Orignal on the Ottawa; an excel- 
lent sandstone for building purposes, from near Pembroke, in Ren- 
frew county, on a higher part of the Ottawa River; and good 
limestones for the same purpose, from Montreal, Caughnawaga, 
Hawkesbury, and other localities. 
The sandstones of the Sault Ste. Marie and surrounding district, 
(formerly regarded as belonging to the Potsdam Group), are now 
thought to be of Chazy age; but otherwise the Chazy formation has 
not been definitely recognized west of Kingston, although it may 
perhaps be slightly developed between the Potsdam sandstone and 
the limestones of the Black River formation in the townships of 
Storrington and Loughborough. In the area east of Kingston, 
between the Ottawa and the St. Lawrence, it occurs somewhat exten- 
sively. Exposures are seen in the townships of Nepean, March, 
Ramsay, Huntley, Hawkesbury, &c., of that region. It occurs also 
largely on the other side of the Ottawa, in the townships of Chatham, 
Grenville, Longueuil (Prescott county), and especially around the city 
of Montreal. It is found likewise in places farther east, between that 
point and the River Chicot ; and again in the Mingan Islands. 
The Trenton Group :—This group derives its name from Trenton 
in New York. The lower beds of the group have been separated 
from the higher beds, and referred to two distinct formations, called, 
respectively, the Bird’s Eye and the Black River Limestones; but in 
Canada, a separation of this kind cannot be definitely carried out. 
As certain fossils, however, are restricted locally to the bottom beds 
of the group, or are more especially characteristic of these, the 
