262 THE JOURNAL OF GEOLOGY. 



Among five hundred bowlders examined by Mr. Buell at two 

 railroad sections, distant less than three miles from the most 

 remote of the parent ledges, only ten were noted that did not 

 plainly show by rounded edges and blunted angles the effects 

 of glacial attrition. At a point less than twelve miles distant, 

 the abrasion had so far obliterated the surface characters that 

 it was hardly possible to determine to which of the three classes 

 above indicated the erratics had originally belonged. Farther 

 on, the evidences of abrasion are still more marked. The degree 

 of abrasion did not appear to be equally great in the case of 

 some of the bowlders found on the crest of some of the high 

 ridges and on the surface of the terminal moraine. Mr. Buell's 

 observations were made with the hypothesis of englacial trans- 

 portation in mind as an accepted working hypothesis, but with 

 only meagre results in the drumlin area. Studies at two points 

 on the slope of the outer ridge of the terminal moraine and on 

 the edge of the overwash plain gave fifty-six bowlders that were 

 only slightly affected by glacial abrasion and eighty-eight which 

 showed by their rounded forms and scratched surfaces the effects 

 of severe glacial reduction. While therefore the observations 

 do not exclude the hypothesis of a small amount of englacial 

 transportation, if slight abrasion be taken as sufficient evidence of 

 this, they limit it to a quite trivial factor of the whole mass. 



The combined testimony of the foregoing facts seems to me 

 quite decisive in its bearing on the proposition that the deriva- 

 tion, transportation and deposit of the quartzite bowlders was 

 almost exclusively subglacial or at least closely basal. As these 

 bowlders enter into the structure of the drumlins from base to 

 summit, and are mingled with much other local material, the 

 foreign element being relatively small, they seem to compel the 

 same conclusion respecting the whole of the material which was 

 built into the drumlin forms. 



Mr. Buell has found what he regards as satisfactory evidence 

 .that an older train of bowlders was carried directly westward 

 at the time of the earlier drift and that the later ice movement 

 toward the southwest crossed this train obliquely and distributed 



