120 ROYAL SOCIETY OF CANADA 
Some idea of the amount of this denudation in the Ottawa district 
can be inferred from the present relations of the strata in connection 
with the great Hull and Gloucester fault. ‘The surface is now a broad 
and almost level plain, yet the displacement must have involved the 
thickness of all the formations from the base of the Potsdam sandstone 
to the Medina shales, with presumably other formations still more 
recent, all trace of which in this vicinity is now removed. 
The question of the occurrence of natural gas or oil in the Ottawa 
basin has never yet been actually tested. The borings already made 
have been placed in locations quite unfavourable for this purpose or, 
in the case of those to the south of the Ottawa river, have penetrated 
the rock formations at but few points. The resemblance of the several 
formations here seen to those found in the St. Lawrence basin where 
explorations in this direction have been carried on in a desultory way 
for nearly twenty years, with some measure of success, has already been 
pointed out. It may be remarked, however, that in several of the deep 
borings which have been made in the clays along the ancient channel 
of the Ottawa, gas was found in considerable quantity. The under- 
lying rocks in this area are presumably of the horizon of the Utica or 
Lorraine shales. 
The gas found in these holes was apparently most abundant along 
certain anticlinals which were indicated many years ago by Sir William 
Logan, as traversing the district in connection with lines of fracture 
in some cases, but the true position of these, owing to the mantle of 
drift, is very difficult to determine. Their exact location is now a ques- 
tion of considerable importance in view of the hypothesis, generally 
sustained by the work:in other fields, that gas should be looked for, 
other conditions being favourable, along the lines of anticlinal structure 
rather than on the synclines. In the present condition of affairs it is 
therefore practically impossible to advance any definite opinion as to 
the precise economic aspect of this question in this area, but it is hoped 
that operations, now in contemplation, will materially add to our 
knowledge in this respect. 

