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shales of the Chazy and in the accompanying calcareous bands : 
Fossils from the Chazy Beds. 
i. Orthis imperator, Billings. 
2. " borealis, Billings. 
3. " platys, Billings. 
4. Rhynchonella plena, Hall. 
5. Raphistoma staminea, Conread. 
6. Modiolopsis parviuscula, Billings. 
7. Orthoceras anterior ? Billings. 
But little time was spent collecting here, which accounts for 
scarcity of forms. 
Black River and Trenton Formations. 
Following the measures in an ascending order the escarpment is met 
with next. This escarpment, which faces the north and presents its bold 
front to the Ottawa Valley at the quarries, belongs to the Black River 
and Trenton formations, or to the Trenton group as it is sometimes 
called. 
The two formations pass imperceptibly from one into the other, 
only an arbitrary line can be drawn to separate them. The lower part 
of the escarpment at the quarries belongs to the Black River formation, 
whilst the upper portion is distinctly Trenton in fades. It was in the 
lower half at the level of the tramway and track, some 15 feet higher 
than the swamp facing the quarry, that the proprietor, Mr. Archie 
Stewart found a large coral mass, which he brought to the museum of 
the Geological Survey for identification. It proved to be the typical 
coral, Colutnnaria Halli, Nicholson. At a higher elevation, some fifty 
feet above the Columnaria horizon, masses of Tetradium fibratum, 
Safford, were found, which are considered characteristic Black River 
forms also, yet these were immediately followed by large colonies of 
Prasopora Selwyni, Nicholson, associated with orthoctratites and 
brachiopoda, of typical Trenton aspect. 
The beds throughout the section proved to be highly iossiliferous, 
but especially so were those in the highest and thin-bedded portions of 
the escarpment. The beds were seen to vary in thickness, but 
