440 A POPULAR EXPOSITION OF THE 
or small isolated patches of conglo- 
meritic rock, referred to the Lower Hel- 
derberg division, have been recognised 
of late years. Their existence was first 
pointed out by Dr. Dawson. They are 
made up of fragments of various rocks, 
gneiss, Trenton limestone, Utica shale, 
syenite, &c-, cemented together by a 
paste of greyish dolomite. These con- 
glomerates are regarded as patches of 
strata once continuous with the Lower 
Helderberg series of eastern New York, 
their removal in intervening areas having 
been effected by denudation. The lime- 
stones and. shales which at Cape Gaspé, 
and elsewhere in that region, rest un- Fie. 227. 
conformably on the dark shales of the  Zurypterus remipes (reduced), 
Calciferous or Quebec formation, are 
likewise referred by Sir William Logan to the Lower Helderberg 
group. These beds are, at present, known provisionally as the 
“ Upper Gaspé Limestones ”’—the lower limestones of the Gaspé 
series, already alluded to as occurring on the Chatte, Rimouski, and 
other rivers of that district, being referred to the Middle Silurian 
period. See the remarks on this point, under the Niagara formation, 
above. 
Devonian Strata.—The rock formations of Devonian age, occurring 
in Canada, are restricted to the following subdivisions (here named in 
ascending order) :—(1), The Oriskany Formation; (2), The Corni- 
ferous Formation; (3), The Hamilton Formation; and (4), The 
Portage and Chemung Group. Of these, however, Nos. | and 4 are 
but very slightly developed. It is in the Devonian strata, it will be 
remembered, (at least as regards this continent) that we find the first 
traces of vertebrated life and of land vegetation. 
The Oriskany Formation.—In Canada the so-calied Oriskany beds 
consist essentially of white or brownish sandstones of both fine and 
coarse grain, averaging about seven or eight feet in thickness. 
These rest on a layer of chert or hornstone. The latter contains 
much iron pyrites; and the bottom beds of the sandstone present 
here and there a brecciated structure, being chiefly made up of frag- 
