POST-TERTIARY PERIOD. 543 



which has its difficulty in the alleged fact (inferred from the 

 scratches and stones) that even Mount Washington was all sub- 

 merged but a thousand feet, and Mount Monadnock to its very- 

 top. 



(3.) It seems very improbable that the scratches made by stones 

 in the bottom of bergs that chanced to be grounded, should score so 

 uniformly and completely the wide surface of a region. The cause 

 would rather make few and distant deep channelings, unless the 

 ice lay regularly over the whole bottom, — a condition which may 

 be that of the foot of a glacier where it enters the sea, but not that 

 of an iceberg. 



(4.) The submergence of the northern part of America as far as 

 the southern limits of the Drift would make a warm climate for the 

 continent, and not a glacial period (p. 45) • and hence there is 

 great difficulty in accounting for either icebergs or glaciers upon 

 this idea. 



2. Glacier theory. — This theory is sustained on the ground — 



(1.) That glaciers are known to transport boulders, gravel, and 

 earth down very gentle slopes as far as glaciers descend: the stones 

 and earth of icebergs were gathered when the ice was a glacier. 



(2.) That the moving glaciers make scratches in the rocks be- 

 neath them, and on boulders or stones, precisely like those of the 

 drift regions as to regularity, kind, number, and all other pecu- 

 liarities ; and that polished and rounded surfaces are other common 

 effects from moving glaciers. 



(3.) That glaciers will move on slopes of one or two degrees: 

 if the whole surface of a continent over the northern. regions were 

 an immense glacier, a very little motion would produce in time 

 great results. 



(4.) That the absence of marine relics and all sure evidences of 

 any sea-shores over the continent above a level of 500 feet above 

 the ocean is so far evidence that the sea did not cover the land in 

 the Post-tertiary period to a higher level than 500 feet. 



(5.) That the fiords afford evidence of an elevation and widening 

 of the continents in the higher latitudes ; and, as fiord-latitudes and 

 drift-latitudes are the same, this epoch of elevation was, in all pro- 

 bability, that in which the Drift phenomena were produced. This 

 evidence from fiords is based on the fact that the valleys which 

 they occupy must have been excavated, like most other valleys, by 

 the action of running water or ice, and this could have been done 

 only when the country along the sea-border was so raised that 

 they were occupied by streams and glaciers from the land instead 

 of the waters of the ocean. (See under Dynamical Geology.) 



