18 THE ICE AGE IN CANADA. 



We may, therefore, safely assume that the refrigeration 

 indicated by these plants would place the region bordering 

 the Ottawa in nearly the same position with that of the 

 south coast of Labrador fronting on the gulf of St. Lawrence 

 at present. The absence of all the more arctic species 

 occurring in Labrador, should perhaps induce us to infer 

 a somewhat more mild climate than this [and also indi- 

 cates the probable existence of the arctic flora to the 

 northward throughout the pleistocene period]." 



" The moderate amount of refrigeration thus required, 

 would, in my opinion, accord very well with the probable 

 conditions of climate deducible from the circumstances in 

 which the fossil plants in question occur. At the same time 

 when they were deposited, the sea flowed up the Ottawa 

 valley to a height of 200 to 400 feet above its present 

 level, and the valley of the St. Lawrence was a wide arm 

 of the sea, open to the arctic current. Under these 

 conditions the immense quantities of drift ice from the 

 northward, and the removal of the great heating surface 

 now presented by the low lands of Canada and New 

 England, must have given for the Ottawa coast of that 

 period a summer temperature very similar to that at 

 present experienced on the Labrador coast, and with this 

 conclusion the marine remains of the Leda clay, as well 

 as the few land mollusks whose shells have been found in 

 the beds containing the plants, and which are species still 

 occurring in Canada, perfectly coincide. 



" The climate of that portion of Canada abo\'e water at 

 the time when these plants were imbedded, may safely be 

 assumed to have been colder in summer than at present, 

 to an extent equal to about 5° of latitude, and this 

 refrigeration may be assumed to correspond with the 

 requirements of the actual geographical changes implied. 



