THE PETROLEUM SPRINGS OF WESTERN CANADA. oot 
The epoch of the deposition of the rocks in question seems to have 
been a time when land and water were struggling for the predominance. 
The vast masses of the Silurian system of rocks had all been deposited 
in deep water; and the Devonian rocks are just beginning to emerge, 
forming vast lagoons, floored and surrounded by coral reefs, and 
densely inhabited by crinoids, brachiopods, and trilobites ; though the 
latter remarkable creatures, so largely developed a little lower down 
in the scale, are now becoming rare and approaching extinction, 
Calamites, the earliest known of terrestrial vegetables, appear struggling 
for existence among the waves and shifting sands ; and the first created 
fishes sport in the shallow waters. The floor of the ocean, together 
with these low spits and reefs, is sinking by slow and intermittent 
stages, and the remains of the scanty vegetation are entombed with 
those of the marine animals. Layer after layer are thus formed, the 
crust of the earth still subsiding as each is deposited. 
Let us now inquire what would be the probable result of this con- 
dition of things, in so far as it affects the present question. The 
organic matter thus profusely scattered along the shores, and subjected 
to the influences of air and moisture, would decompose in the ordinary 
manner ; but when, after partial putrefaction, it was covered up by a 
layer of sand or calcareous mud, and thus removed from the atmos- 
pheric influences, the resulting gases would be confined as in a closed 
retort ; and the carbon and hydrogen, being greatly in excess of the 
oxygen, would enter into such combinations as we find subsisting in 
the petroleum and the various hydrocarbon gases; and these would 
remain pent up in crevices or caverns in the rocks until liberated either 
by natural or artificial means. In some cases, circumstances might be 
favorable for the production of the gaseous products unaccompanied 
by the fluid ; and it by no means follows, as many imagine, that the 
development of gas, even in great abundance, would be an indication 
of the existence of oil in the same reservoir. The remarkable cir- 
cumstance of the almost invariable association of salt water with 
petroleum would appear to afford a corroboration of this theory ; for 
whether it be true, as some suppose, that the chloride of sodium 
exerts some chemical action on the bituminous matter favoring its 
production, it is at all events certain that the relative dispositions of 
land and water, which I have attempted to describe, would be highly 
favorable to the production of sea salt. 
Whether this theory be correct in all its details or not, it seems cer- 
