178 THK IMIKNOMKXA OF DRIFT, OR 



distribulion of llio l^owklers; ihat is, on tlioir northwestern and 

 southeastern sides; and in valleys running in that direction. He 

 will find the tops of the mountains more deeply abraded than 

 their slopes. And what is more decisive, he will find that since 

 the period of glacio-aqueous agency, no vertical movements have 

 taken place, whereby one portion of an abraded and striated sur- 

 face has been raised one inch above another part. I have never 

 seen such an example. Now, when we recollect that most rocks 

 are full of cracks and fissures, will any one believe that a partic- 

 ular mountain can have been lifted hundreds and thousands of 

 feet williout producing any such displacement? The idea is 

 absurd ; especially when we recollect the effects often produced 

 by slight earthquakes. And an equally strong argument may 

 be drawn from the undisturbed state of the moraines, frequently 

 found upon the lianks of mountains. Indeed, we may set it 

 down as a settled principle, that the relative levels of the surface 

 have not been essentially changed since the period of this action. 

 If vertical movements have taken place, they have affected vast 

 areas, and not particular mountains or districts. 



Another theory which suggests itself, supposes that the abra- 

 sion of the tops of the mountains took place while the entire con- 

 tinent was beneath the ocean ; and that, as it gradually emerged, 

 the sides and bottoms of the valleys were subjected to the same 

 process. I shall consider this general theory more particularly 

 in another place, and shall here merely mention one difficulty in 

 the way of its adojition, that seems to me very strong. After the 

 tops of the mountains had risen above the waters, it is evident 

 that tlie currents, urging fonvard the ice that formed the striae, 

 would now pass around, and not over, the diy land, so that the 

 strisB, except at the very tops of the mountains, ought to pass 

 horizontally along their flanks, and at length become entirely 

 confined to the valleys that now exist. But, as we have already 

 seen, this is not generally the case, certainly not in New England, 

 for the striae are frequently seen at very low levels, having the same 

 southeasterly direction as on the mountains. It is true that their 

 direction at the tops of our higliest peaks, as Mount Washington, 

 Monadnoc, Wachusett, and Mount Everett, differs somewhat from 



