i82 The Ottawa Naturalist. [January 



west, will cut all the points at which the line of fault between 

 the Black River and Trenton are seen, though there are several 

 minor breaks clearly visible at a number ot places intermediate 

 between the two extremities of this line. This fault is particu- 

 larly well exposed at Tetreauvillc, along the railway and on the 

 shore ; at Mechanicsville, at the west side of the deep cove, and 

 on several of the roads in this village ; along the line of the Ottawa 

 and Parry Sound railway, and at the Hog's Back. South of 

 the Richmond road, near Skead's Mill, Black River limestones 

 are also exposed to the line of the railway and these beds ap- 

 pear to pass beneath the escarpment of Trenton which occupies 

 the area between that road and City View post office. 



To the east of the city the beds of the Black River are seen 

 at the entrance of Beechwood cemetery, overlaid by the Tren- 

 ton on the south and east of this. In the direction of Green's 

 Creek, this formation keeps to the north of the Montreal road 

 in the vicinity of Robillard's quarries which are in the overlying 

 Trenton. From this place it can easily be followed in escarp- 

 ments and broad ledges to the crossing of the South Nation 

 River, being well observed at Rockland and Clarence Creek 

 about three miles south of the Ottawa. In this direction also 

 almost continuous exposures are seen along the road between 

 ranges II and III, Gloucester, for several miles, or nearly to the 

 eastern line of Carleton county. The characteristic corals of 

 the formation can be obtained in abundance at all these places. 

 They are also well seen to the south of the village of Cumberland 

 and form broad, nearly flat lying, ledges for a long distance. 



West of the fault in Mechanicsville the limestones of the 

 Black River are also well exposed along the line of the Can- 

 adian Pacific railway as far west as Skead's Mill corner, where 

 the formation passes down into the Chazy. 



The Trenton formation is probably the most widely dis- 

 tributed in the city of Ottawa and vicinity. It is also well de- 



