372 Editorial Comment. 
be desirable in one who undertakes to propound a new theory 
on so difficult a subject. 
According to his statement the oil-bearing strata of Europe 
belong chiefly to the Tertiary or later ages. He therefore 
admits that the Carboniferous deposits beneath them may 
possibly be the source from which their oil has been derived. 
But he adds that the oil-bearing sands of North America 
belong to the Devonian or the Silurian strata in which few or 
no organic remains have been found. If the Coal Measures 
were the source of the oil it would never, says he. have gone 
down into the underlying Devonian rocks of Pennsylvania 
through the intermediate shales and clays, so that it is not 
possible to attribute its origin to the secular changes j^roduced 
in coal by heat and pressure. 
It seems incredible that such a statement can have been 
made by any one acquainted with the abounding fossils of 
these rocks in Canada and the United States, where whole 
layers consist in some places of almost nothing but the relics 
of bygone life, both animal andvegetable. Thisisthe case with 
many beds in the Trenton and Hudson River groups. The Devo- 
nian rocks in the eastern and midland states are also filled with 
similar remains, especially of marine invertebrata and fishes, 
while some strata of this latter system in places consist of 
little save the minute sporanges of aquatic cryptogams, indi- 
cating an abundance of these plants at that date, which it is 
difficult to realize. 
The prevalent opinion among geologists is that petroleum 
results from the slow secular changes that take place sponta- 
neously, as it were, in such masses of organic matter as we 
have just indicated. Sea-weeds and plants of their low grade 
leave, in most cases, no distinct fossil remains, but their decay 
produces a quantity of bituminous material which may be 
represented merely by the black carbonaceous substance of 
the shales. It is only when, as in Ohio, such shales containing 
more or less bitumen in their mass are overlain by a porous 
sandstone and that in turn by an impervious layer of shale 
that the conditions are fulfilled and a store of gas or of oil 
results. A porous limestone may take the place of the sand- 
stone and a bituminous limestone may play the part of the 
shale, as in northern Ohio, but the general conditions remain 
