176 ROYAL SOCIETY OF CANADA 
stations along the entire route will be found in an appendix, in which the 
figures-as given in the reports of the canal engineers, have been carefully 
corrected by Mr. James White, chief cartographer of the Geological Survey 
Department, in accordance with the most recent hydrographic surveys. 
Indications of changes of level in past times are readily observed at 
many points along the course of the Ottawa River in the presence of ter- 
races, drift sands and clays and old river channels, which have since been 
closed through the accumulation of drift material, as sands and gravels, 
and the waters again diverted to their original course. Among these old 
water courses one may be noted at the Des Joachims Rapid to the north 
of the present river channel, which it reached by way of McConnell Lake 
and stream through the depression north of the village of Des Joachims 
itself. Another evidently turned off from the Deep River about fifteen 
miles below the Des Joachims Rapids, and extended by way of the Sturgeon 
Lake and Bay, into which the waters of the Chalk River now empty, 
thus cutting off the bold headland known as the Oiseau Rock on the Deep 
River and the high point at the sharp bend of the river below called High 
View. The banks of the Ottawa below the outlet of this old channel are 
composed of great masses of reddish sand, forming banks from twenty to 
sixty feet in height, which extend along the course of the stream for 
some miles. A second former channel evidently extended from the town 
of Pembroke, by way of the Muskrat River and Lake, from which the 
course can be traced by a series of depressions, dotted by a chain of lakes 
to the present channel on Chats Lake, near the Chenaux Rapids, several 
miles above the mouth of the Bonnechére. Opposite the city of Ottawa 
also another channel is seen in rear of the city of Hull ; while it is pro- 
bable that still another channel passed to the south of the city of Ottawa 
by way of the Hintonburg depression and Dow’s Swamp into the present 
channel of the Rideau. 
The deposits of sand and clay on the lower Ottawa are in places of 
great thickness, and show that the denudation of the old channel must 
have been very heavy. Between the Laurentian range at Lachute and 
the Lake of Two Mountains bore-holes have been sunk to a depth of 120 
feet without reaching the underlying rock, while terraces of drift rise to 
the north of the boring to a height of from fifty to sixty feet, thus show- 
ing that the drift deposits must be not far from 200 feet in thickness at 
this place. The exposures of marine clay with characteristic fossils, 
found on Lake Coulonge, more than 200 miles west of Montreal, at eleva- 
tions of 360 feet above the sea level, show that the waters of the ocean 
extended for a long distance inland during the period of depression. 
The sedimentary Palæozoic formations found along the Ottawa River 
and in its vicinity include all from the Potsdam to the Lorraine shales 
which mark the summit of the Cambro-Silurian system. The greater 
part are well characterized by the fossils peculiar to each formation, and 
ut 
