ORIGIN OF THE UNDERLYING CLAYS. DAT) 
part of the area is only negative evidence to the contrary, and there are 
certain facts that go far to establish this theory of their marine deposition. 
In support of this view we may mention that all the evidence points 
to the fact that the estuary of the lower Ottawa was continuous in im- 
mediately Postglacial times, as it is at the present day, with that of the 
lower Saint Lawrence, and that there is no evidence to show that these 
two basins were ever separated subsequent to the Glacial period. 
The observations of Mr R. Chalmers along the lower Saint Lawrence 
and throughout that portion of Quebec to the east have clearly proved 
that there has been a submergence of this whole area now occupied by 
the Saint Lawrence basin to a depth of nearly or quite 1,000 feet, as in- 
dicated by well defined marine beaches which front the present Saint 
Lawrence valley. The indications of this submergence are equally clear 
on the west side of this river, and, tracing this old shoreline westward up 
the Ottawa, the same observer has recently found equally good evidence 
in the form of beaches that this submergence extended westward, as 
these lines facing the open estuary of the Saint Lawrence were noted at 
an elevation of about 1,000 feet in the area to the north of Lachute, 
about 40 or 50 miles west of Montreal. The presence of old beaches, 
well defined, can also be readily recognized at a number of points west 
of this, above the city of Ottawa, and it thus appears that the waters of 
the postglacial ocean extended westward to a great distance. A submerg- 
ence of 900 to 1,000 feet would carry the waters of the Ottawa estuary 
well over the height-of-land to the north and thus connect these with the 
waters of James bay. 
SAND AND CLay Derposirs SouTH OF THE Orrawa 
The Bonnechére river, one of the tributaries of the Ottawa from the 
south, presents several interesting features in this connection. To the 
south of the town of Pembroke a great part of the surface to the north 
of Golden and Round iakes, which are expansions of this stream, as also 
the country along the course of the river west of this point, are covered 
with a great thickness of sand, and this deposit extends south to the foot 
of the Brudenell range of hills about 12 miles south of the Bonnechére 
river. These sands are well exposed in the valley of Clear lake, which 
lies along the foot of the mountain ridge in the township of Sebastopol, 
and the sands extend for many miles in either direction. The elevation 
of Clear lake is 745 feet above sea, and between this and the Bonnechére 
to the north the deposits of sands and clays are almost continuous. A 
short distance east of these the clays of the lower Bonnechére, west of 
Renfrew, come in, and are apparently continuous with those of the area 
