153 
western margin of Nepean bay. At the bay the downthrow 
is on the east, so that the crinoid beds of the Trenton are 
brought against the Black River; the displacement being 
therefore only 50 or 60 feet (15.2 or 18.3 m.). There are, 
however, several faults parallel to the main one, which con- 
siderably disturb the strata to the east and give a steep 
dip to the beds on the islands in the river. Along the shore 
to the west is a shallow syncline, which exposes the very 
fossiliferous strata of the Black River for a considerable 
distance. Large cephalopods, including Hormoceras te- 
nuifilum, are common here, and other fossils such as Colum- 
naria halt, Strophomena filitexta, Dalmanella_ gibbosa. 
Bumastus mullert, and Isotelus gigas can be readily obtained, 
A great many other species have been found here, and this 
is the type locality for Cybele ella. 
Farther west the dip of the beds is reversed, and the 
Lowville comes out below the Black River. The Lowville 
here consists of pure, buff-coloured, fine-grained limestone, 
containing such fossils as Tetradium cellulosum, Bathyurus 
extans, and Bathyurus spiniger. The lowest layers contain 
Beairicea and Cyrtodonta huronensts, as in the section on 
the hill behind Aylmer. A small fault at this point brings 
the upper part of the Pamelia against the Lowville. The 
hard limestone near the water level west of this fault fur- 
nished the types of Bathyurus superbus. It also contains 
Tetradium and other fossils. Still further along the shore 
a yellowish magnesian limestone was formerly quarried 
and used as a natural cement. 
GOVERNOR Bay. 
Trenton, Black River, and Pamelia.—Governor bay is 
a small indentation in the shore line of Ottawa river near 
the entrance to Rockcliffe park. The first outcrop encoun- 
tered in descending to the bay from the electric car barns 
is the shaly limestone of the Prasopora zone of the Trenton. 
These beds are exceedingly fossiliferous and contain Dalma- 
nella rugosa, Plectambonites sericeus, Zygospira recurviros- 
tris, Sinuites cancellatus, Calymene senaria, and Isotelus 
gigas. Other fossils, however, can also be found. The 
Prasopora layers rest on the thick gray strata of the Tetra- 
dium zone, but Tetradium itself has not been found here. 
The strata in the bluff above the Prasopora beds belong to 
the crinoid zone of the Trenton, and the Prasopora beds 
