74 THE CANADIAN NATURALIST. [Feb. 



II. Climate indicated. 



None of the plants above mentioned is properly Arctic in its 

 distribution, and the assemblage may be characterized as a selec- 

 tion from the present Canadian flora of some of the more hardy 

 species having the most northern range. Green's Creek is in the 

 ceutral part of Canada, near to the parallel of 46°, and an accidental 

 selection from its present flora, though it might contain the same 

 species found in the nodules, would certainly include with these, 

 or instead of some of them, more southern forms. More especially 

 the balsam poplar, though that tree occurs plentifully on the 

 Ottawa, would not be so predominant, But such an assemblage 

 of drift plants might be furnished by any American stream flowing 

 in the latitude of 50° to 55° north. If a stream flowing to the 

 north it might deposit these plants in still more northern latitudes, 

 as the McKenzie River does now. If flowing to the south it 

 might deposit them to the south of 50°. In the case of the 

 Ottawa, the plants could not have been derived from a more 

 southern locality, nor probably from one very far to the north. 

 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 Gkdf 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. 



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 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. 



