26o THE JOURNAL OF GEOLOGY. 



derived from a stream of drift passing over the quartzite ledges 

 and making constant additions from them. 



2. The drumlins are found to be filled with quartzite erratics 

 immediately in the lee of the ledges. There are even drumlins 

 which lie directly upon the ledges and envelop them in large 

 part, which are found free from local quartzite derivatives on 

 their stoss ends, but are inset with them in their lee ends. The 

 quartzite content of the leeward portion ranges, in observed sec- 

 tions, from 5 per cent, to lo per cent, of the whole drift. In one 

 case, Mr. Buell found an isolated drumlin to contain all of the 

 quartzite of its particular kind observed in the vicinity. It 

 evidently completely envelops the parent ledge and retains 

 the most of its derivatives. Several bowldery mounds, that 

 may be regarded as drumlins in miniature, occur in the immedi- 

 ate lee of the ledges, in which the quartzite drift was estimated 

 to comprise from 20 per cent, to 75 per cent, of the whole. 

 The material, in these instances, appeared to be chiefly 

 former talus of the quartzite outcrops. Setting in thus 

 promptly immediately at the quartzite outcrops, the erratics 

 are found to diminish very markedly in proportion as the dis- 

 tance increases. A mile and a half away from the outcrops, a 

 careful estimate of the quartzite content gave 3 per cent, of the 

 whole mass of the drift. The average for the area between i 

 and 6 miles is i-i^ per cent.; between that and 20 miles i per 

 cent.; between that and 45 miles .364 per cent., and in the ter- 

 minal moraine .0477 per cent. The surface distribution shows a 

 similar diminution. The estimated amount of quartzite on the 

 very bowldery mounds near the ledges was 17,700 cords; at 

 other points within six miles of the outcrops 12,650 cords; at 

 medial points 1,409 cords; on the terminal moraine, about 45 

 miles distant, 747 cords. This very rapid diminution in the quan- 

 tity of quartzite erratics is significant in showing that the element 

 of resistance to transportation was an influential factor. This is 

 precisely what is to be anticipated on the hypothesis that these 

 bowlders were pushed or dragged along the base of the ice. It 

 seems very far from what is to be expected, however, on the 



