114 ROYAL SOCIETY OF CANADA 
While the strata of the several formations, as a rule, lie in a nearly 
horizontal attitude in both these areas, and the surface over large por- 
tions of the country is without any marked elevation, the presence of 
lines of dislocation is seen at many points. ‘These fault lines are of 
great interest, not only as affecting the continuity of formations and 
complicating the geological structure, but as affecting the results of the 
explorations for gas and oil which have been carried on for some years, 
in both the St. Lawrence and the Ottawa basins and in which further 
search is contemplated. 
The position of some of these faults which occur in the area south 
of the Ottawa river is given in the Geology of Canada, 1863, but since 
that date their further tracing has been attempted as well as the drift- 
covered nature of the country would permit. Some of the details thus 
obtained may be here stated as having a bearing on the economic aspect 
of the question. 
Of these dislocations the most extensive apparently is that which 
is described in the volume just referred to as the Rigaud and Fitzroy 
anticlinal. This, however, is in certain parts rather of the nature of a 
fault than a folding of the strata for a great part of its extension. Its 
starting point is presumably the Rigaud mountain, with vhe upheaval 
of which it appears to be connected. Eastward of this hill it has been 
traced across the St. Lawrence into the county of Beauharnois where it 
now affects the strata of the Potsdam and Calciferous formations only, 
since the more recent sediments have been removed by denudation. 
From the west end of Rigaud mountain, however, an important 
line of fracture extends westward to the vicinity of Ottawa where, in the 
western. part of the township of Russell, a second line of fault. branches 
off to the north-west and crosses the Ottawa river in the western part 
of Ottawa city, and extends into the township of Hull. This second 
break is known as the Hull and Gloucester fault. After crossing the 
Ottawa it bends to the east of north and reaches the Gatineau river in 
the vicinity of Wright’s bridge, about three miles north of the junction 
of this stream with the Ottawa river. West of the point of junction of 
these faults in Russell, the continuation of the main line of fracture or 
folding, is supposed to extend through the townships of Nepean, Hunt- 
ley and Fitzroy into MacNab, meeting the Ottawa river near the town of 
Arnprior. 
The tracing of the Rigaud and Russell fault for the entire distance 
is rendered impossible, owing to the great covering of drift which has 
already been referred to. It is apparently met by another heavy break 
which comes south from the vicinity of the village of Rockland, which 
is about thirty miles below Ottawa on the river, and which has had an 

