[ELLs] GEOLOGY OF THE OTTAWA PALÆOZOIC BASIN 115 
important effect on the several formations which it traverses. The 
occurrence of these faults in this area must have a manifest influence 
in the consideration of the problem of the finding of gas or oil in this 
part of the Ottawa basin. 
The formations affected by the Rigaud fault for some miles west of 
the Rigaud mountain, range from the Potsdam sandstone to the Trenton. 
The dislocation is well seen in east Hawksbury, where the rocks are 
well exposed a short distance west of the village of Ste. Anne de Pres- 
cott over a considerable area. A short distance west of this village and 
north of the road, at the crossing of the river a la Graisse, the Black 
River limestone dips to the south-west at an angle of ten degrees, but 
south of the road the surface is occupied by the Potsdam sandstone. 
To the south-west of this the formations upwards to the Trenton succeed 
each other with a fair amount of regularity. 
Following the main line of fracture from this place in a north- 
westerly direction, the Trenton and Black River limestones appear on 
the north side of the dislocation for some miles. The corresponding 
beds on the south side, however, are of Calciferous and Chazy age, and 
the first outcrop of the Black River limestone on, this side of the fault is 
about nine miles west of that seen on the north side. There would 
therefore appear to be a horizontal thrust to the north-west along the 
line of fracture of about that distance. West of this for some miles the 
Trenton appears on the south side, but the fault cannot be traced owing 
to the mantle of drift. 
In the township of Clarence, rock outcrops again appear-and the 
Rockland fault already referred to is disclosed, apparently following a 
line of anticline which crosses the Ottawa river near the village of Rock- 
land, and extending south-east in the direction of the Rigaud fault just 
described. By this anticline and break the Chazy, Black River and 
Trenton formations are affected, and the formations on the east side are 
thrown to the north for a distance of about four miles. It would appear 
from this that a second line of horizontal displacement west of Rigaud 
extends in this direction. This line of fracture may be styled the Rock- 
land and Clarence fault. 
The Hull and Gloucester fault already referred to as crossing the 
Ottawa and extending to the Gatineau is an important one. By it the 
formations along the Ottawa river, east of Ottawa city where these cross 
the river from the south side, are abruptly terminated westward by the 
crystalline rocks of the King’s mountain ridge, against which they are 
in contact for about three miles. In the area west of the city of Hull 
the fault is easily seen, and it there affects the strata belonging to the 
R Sec. IV., 1900. 6. 
