(^ the White Mountains. 93 



Another aspect of the inquiry which has perhaps not been re- 

 garded with sufficieot attention, is that which relates to the re- 

 duction of temperature, which might be consequent on the great 

 •depression of the land which we know to have existed at the close 

 of the tertiary period, a fact on which I have insisted in former 

 papers on the Post-pliocene deposits of Canada.* A very clever 

 writer on the subject of geographical distribution,f has pictured 

 the case of a subsiding continent with the fauna and flora of its 

 lowlands becoming gradually concentrated on the spots which 

 had previously been alpine summits, but now reduced to low and 

 temperate islands. But he has left out of view the fact, that if 

 land still existed in mass in the arctic regions, and if the subsid- 

 ence was that of land in temperate regions, then on the principles 

 long ago so well stated by Sir C. Lyell, these islands might have 

 a mean temperature far below that of the former plains, and might 

 in consequence be suitable only to such an alpine flora as that 

 which they had previously borne. 



Now this is precisely what occurred in the I^ost-pliocene pe- 

 riod. The arctic land remained in great mass, detaching into 

 the sea annual crops of icebergs, which have strewed all the north- 

 ern hemisphere with boulders : the temperate regions were sub- 

 merged except a few insular spots. These are the very con- 

 ditions required for a low mean temperature both in the sea and 

 on the land, and these geographical conditions correspond pre- 

 cisely with the facts as indicated by the fossil animals and plants 

 of the period. 



Further, it would be easy to show that the alpine plants of 

 Mount Washington would thrive under such conditions as those 

 supposed, at the sea level ; a low and equable temperature with a 

 moist atmosphere being that which they most desire, and their 

 greatest enemy being the dry parching heat of the plains of the 

 temperate regions. Those of them, such as Potentilla tridentataj 

 Linncea borealis^ and Alsine Groenlandica, wliich occur within the 

 limits ot the United States, are found under shaded woods, in 

 damp ravines, or on the moist sea coast; and as we follow the 

 coasts northward, we find these plants on thesc^ and on neighbor- 

 ing islands, in lower latitudes than those in which they occur in- 

 land. When the summer mists roll around the summit of Mount 

 Washington, it is in every respect the precise counterpart of an 



* Canadian Naturalist, Vol. IV. f Wollaston. 



