TRACES OF ANCIENT GLACIERS IN MASSACHUSETTS AND VERMONT. 



Whoever is familiar with the phenomena of drift in this country, and has 

 examined the effects of glaciers in the Alps, will be struck with the .resemblance 

 in most respects, and may perhaps infer a complete identity. I cannot, for the 

 reasons already assigned in my paper on Surface Geology, adopt this opinion, but 

 suppose it possible to distinguish between the two agencies by the following 

 marks : 



1. By the direction of the strice and the position of the stoss side of the roches 

 moutonnes. There is great uniformity and almost parallelism in the drift striae in 

 our country over wide surfaces. If, therefore, we find other stria? differing in direc- 

 tion very much from these, and the marks also having their stoss side very differ- 

 ent as to the cardinal points, the presumption is strong that the more limited stride 

 were produced by glaciers. 



2. Glacier striaa are limited to valleys, and proceed from the crests of the moun- 

 tains outwardly, and the stoss side of the embossed ledges is always the upper 

 side, that is, it faces up the valley, showing that the abrading body descended the 

 valley. But drift striaa, although frequently found in the valleys, are also common 

 upon the tops of the mountains ; in this country with only one exception that I 

 know of, viz: Mount Washington, in New Hampshire, which seems to have been 

 above the agency. 



3. The strise of glaciers always descend from higher to lower levels, except in 

 limited spots, where they may be horizontal. But drift strise frequently ascend, 

 the stoss side of hills and mountains, hundreds of feet high, being the lower side. 



4. Drift is spread more or less promiscuously over most of the surface : but the 

 detrital matter swept along by glaciers, occurs, either as lateral moraines along the 

 sides of valleys, or accumulated in greater quantity where the valley makes a 

 curve, or blocking up the valley as terminal moraines. In the latter case, how- 

 ever, the modern river occupying the valley, has usually worn away a part of the 

 moraine, and during that process, it may be, has partially covered the other part 

 with modified drift in the form of terraces. 



Within the last five years I have had an opportunity to apply these principles 

 in three widely separated countries, viz : Wales, Switzerland, and New England. 

 I made a practical application of them in Scotland, but not with so satisfactory 

 results. 



