444 A POPULAR EXPOSITION OF THE 
building materials; but the Corniferous formation is chiefly of im- 
portance, in an economic point of view, as the supposed source of the 
great oil supply of this western region. As the oil-wells in successful 
operation, however, occur entirely within the central area, across which, 
as stated above, the Hamilton formation extends, their discussion will 
be entered into in connexion with the latter series of strata. 
In Eastern Canada, the Corniferous formation is undoubtedly repre- 
sented by a portion of the Gaspé deposits, and probably also by some 
of the altered strata of the Eastern Townships. The beautiful yellow- 
veined marbles of Dudswell are thought to be of this age. In Gaspé 
likewise, as near Douglastown and elsewhere in that district, petroleum 
springs occur in Devonian strata referrible either to this series, or to 
the somewhat lower horizon of the Oriskany Formation. 
The Hamilton Formation.—The name of this formation must not 
be confounded with that of Hamilton in Canada: a city situated on 
strata (the Medina) of a much lower geological horizon. As a mis- 
conception of this kind often occurs, it is almost to be regretted that 
our Provincial Geologist did not in this instance depart from the usual 
and strictly legitimate plan, and propose for the group in question 
a Canadian or paleontological name. It might be called appropri- 
ately the Lambton or Goniatite formation, the latter type first appear- 
ing in the beds of this series. The term “Hamilton,” as at present 
applied to the group, is from the village of that mame in Madison 
County, New York. The American geologists usually subdivide the 
formation into three groups, distinguished chiefly by lithological cha- 
racters. The lowest group consists of dark bituminous schists known 
as the Marcellus shales; the second group, or Hamilton group proper, 
is made up of argillaceous and other shales or flags, with an inter- 
stratified bed of encrinal limestone, and in some places an overlying 
limestone bed called the Tully limestone; finally, the third or upper- 
most group is composed of dark shales closely resembling those of 
the first division, and known as Genesee shales. Some observers 
separate these latter, however, from the Hamilton formation, and 
place them in the succeeding Portage group: a view adopted by the 
Canadian Survey. The Marcellus shales thin out greatly towards 
the west; and on entering Canada, the formation appears to consist 
only of the second group ; but its junction with the underlying Corni- 
ferous strata has not yet been observed. It crosses the counties of 
Norfolk, Elgin, Kent, Middlesex, Lambton, and the south part of — 
Huron; but is much obscured throughout by overlying Drift deposits. 
