222 R.W. ELIS—SANDS AND CLAYS OF THE OTTAWA BASIN. 
the more recent, since subsequent to the passing of the glacier many 
changes have taken place, due to the later period of submergence. 
CONCLUSIONS 
From the physiographic conditions of this portion of Canada it would 
therefore appear that the Saint Lawrence and the Ottawa rivers consti- 
tuted a broad open estuary extending eastward to the sea, and that the 
waters of the ocean at one time continued westward into the upper Great 
lakes. In Quebec, east of the Notre Dame range of mountains, in the 
eastern townships, a somewhat similar estuary apparently extended into _ 
_ the waters of the gulf of Saint Lawrence, following the depression of the 
upper Saint John river. It is also probable that some of the divergent 
ice-markings in the area comprised in the lower Ottawa and Saint Law- 
rence basins were caused by masses of floating ice subsequent to the 
period of general glaciation, and to this cause is apparently due the dis- 
tribution of many of the masses of Paleozoic limestone and crystalline 
rocks which are now found in places resting on the marine clays and 
Saxicava sands, not only in eastern Ontario, but at many points in the 
eastern townships of Quebec, since their present position can only be 
accounted for by the agency of some cause subsequent to the deposition 
of the boulder-clay, and as a consequence ata time more recent than the 
period of glaciation of the Ottawa and Saint Lawrence basins. 
It does not fall within the scope of this paper to discuss the sands and 
clays of the great lakes. These are fully described in the Geology of 
Canada,* in so far as the information available at that time permitted. 
From the descriptions there given it would appear that there are two series 
of deposits, of which the lower or Hrie clays are unconformable to the upper 
or brown clays. The Erie clays are very similar in character to those 
seen along the Ottawa and the Saint Lawrence, but they have not as yet, 
in so far as reported, yielded marine organisms. ‘This is, however, only 
negative evidence, and it is probable that the Erie lower clays are the 
true representatives of the marine clays of eastern Canada. If the theory 
put forward that the ocean waters extended westward throughout the 
upper Ottawa basin to an elevation of 1,000 feet above present sealevel 
is the correct one, this hypothesis may well be maintained. It is pre- 
sumable that the upper series of clays, with sands, may have been de- 
posited as fresh-water conditions asserted themselves on the elevation 
of the land after the period of greatest submergence, but further detailed 
work in this area will be necessary before final conclusions can be stated. 
* Geology of Canada, 1863, pp, 896-907, 
