HISTUKKAL NOTICKS. 19 



In oilier words, if Cimiula was siiliiiii'VLCctl until the 

 Ottawa valley was converted into an estuary inhabited hy 

 siiecies of Lvtia, and fre(iuented l»y capelin, lli(( diniinulion 

 of the summer heat eonse([U(!nt on such depression, would he 

 precisely suitable to the plants occurring- in these deposits, 

 without assuming' any other cause of chaii^'e of climate." 



This extract, referrinj,' as it does to the evidence of 

 ])lants, reminds us of the contrast between tlu; Pleistocene 

 and the warm climate of the early Eocene and later 

 Cretaceous, when warm temperate plants could llourish 

 as far north as (Treenhind. The reason is sccmi in our 

 comparative maps of the Cretaceous and I'leistocene of 

 Canada. The conditions presented in the latter show the 

 {greatest possil)le facilities for the triinsferencc of arctic 

 ice to temperate latitudes, and its accumulation therein, 

 while leaving the extreme arctic coni]>aratively free of 

 ice. Such conditions are the reverse of those in the early 

 Eocene, when the interior of the continent was occupied 

 with a warm mediterranean sea, shielded from the arctic 

 ice. Thus the known uieoj^raphicd condition of the I'leis- 

 tocene harmonize with rational views as to the causes and 

 extent of the refrigeration. 



Lastly, in my address to the Natural History Society 

 of Montreal, in 1873, immediately after the pulJication of 

 the " Notes," above referred to, the following reference to 

 the position of the (piestion occurs: — 



" In the memoir in the Journal of the Natural History 

 Society already referred to, I have re-asserted and sup- 

 ported by many additional proofs the theory of the 

 combined action of floating ice and glaciers in the produc- 

 tion of our Canadian l)0ulder clay and other superficial 

 deposits, which I have for many years maintained, in 

 opposition to the views of the extreme glacialists. It is 



