22 



The Ottawa Naturalist. 



[April 



of these must have affected the surface or crust by a vertical uplift 

 of many hundreds of feet. The amount of the latest recorded 

 movement can be, to some extent, estimated by the present 

 position of certain terraces which occur along- the Ottawa and 

 St. Lawrence rivers. These are found at elevations ranging- as 

 high as 900 feet above sea-level on the the slopes of the mountains 

 east of Montreal, while on the upper Ottawa and around Lake 

 Nipissing terraces are recorded at even greater heights. Thus 

 high level beaches in the vicinity of North Bay were recorded by 

 Mr. F. B. Taylor* at elevations cf 1100 to 1200 feet and were 

 regarded by him as of marine origin. Along the Ottawa, below 

 Mattawa, Mr. R. Chalmers records beaches and sand terraces at 

 elevations of 1000 feet and more, and further adds "Extensive 

 deposits of sand and silts, implying submergence are spread over 

 this part of the country up to a height even greater than that oi 

 the beaches referred to which have been described in earlier reports 

 of the Geological Survey as Algoma sands*. 



These sands were formerly supposed to be due to fresh-water 

 agencies, but subsequent investigation has shewn that portions of 

 the deposits thus styled contain marine organism, especially along 

 the lower Ottawa, while their similarity in many respects to those 

 which have been styled Saxicava s-ands in the lower St. Lawrence 

 basin and which are held to be of marine origin, is very remark- 

 able. 



While therefore the Ottawa at some time flowed in a tolerably 

 direct line from the mouth of the Mattawa to the St. Lawrence, 

 certain causas have interposed at different periods to deflect the 

 waters from their original course and to cause them to excavate 

 other and newer channels. In an examination of the valley of the 

 river these interruptions will be found at various points. Thus in 

 that portion of the river between the Mattawa and the head of the 

 Deep River, a distance of fifty-four miles, the channel is fairly 

 straight. Several heavy rapids and falls however occur among 

 which may be mentioned Des Joachims, Roche Capitaine, Deux 

 Rivieres, La Trou, L'Eveille, &c. 



^Bulletin Geol. Soc. Am., Vol. V, 1893. 

 *Rep. Geol. Sur. Can.. Vol. X. p 18 J. 



