[ELLS] GEOLOGY OF THE OTTAWA PALÆOZOIC BASIN 113 
place the measurements for the Utica and the Lorraine gave 1037 feet, 
of which the lower 318 feet have been referred to the former. In the 
detailed section given in the Geology of Canada, 1863, for this place, 
there was included in the upper member certain black shales and lime- 
stones which have since been found to belong to a much lower horizon 
and cannot therefore be considered in this connection. 
The thickness of the Utica cannot be measured at Montreal, nor in 
the flat country east of that city, owing to the limited exposures. At 
Ottawa it is supposed that the thickness is much less than in the eastern 
area, and nowhere probably much exceeds one hundred feet. 
There is no break in the succession of the strata between the Utica 
and Lorraine. The passage between the two formations is gradual, and 
the latter differs in the general absence of bituminous matter, while 
the fossils of this division are also distinct from those in the Utica. 
In the western portion of Ontario the thickness of the Utica and 
Lorraine formations has been stated from exposures at several points. 
Thus at Owen Sound the latter is said to aggregate about 500 feet. At 
Manitoulin island the former shows about fifty feet of shales, while at 
several places in the vicinity, the thickness of the Lorraine ranges from 
200 to 300 feet. 
The highest member of the series in the Ottawa basin itself is pre- 
sumably the Medina. This is represented by certain red shales which 
are seen in the northern portion of the township of Russell and in the 
townships of Cumberland and Osgoode adjacent. The thickness of 
these is not very great, presumably at no point more than seventy-five 
feet. In the St. Lawrence basin, however, near St. Grégoire, in a 
boring at that place, the drill passed through 565 feet of these red 
shales, with a depth of overlying drift of seventy-five feet. The under- 
lying rock was supposed to represent the Lorraine shales and was pene- 
trated to a further depth of 475 feet. From the nature of the report it 
would seem possible that the strata passed through in the lower part 
of this depth more closely represent the Utica shales than the Lorraine, 
and the measures may in that case be affected by faults at this point, 
as broken strata are seen not far away. 
In this connection it may be remarked that there is a manifest 
resemblance between the rocks of the Ottawa basin and those seen along 
or near the St. Lawrence between Montreal and Quebec. Here also 
there is the same regular sequence of formations from the Potsdam sand- 
stone to the Medina as seen in the area east of lake St. Peter, though, 
as already stated, the upper member or Medina has at that place a much 
greater thickness as determined by borings than in the area near Ottawa. 
