DRUMLINS OF MICHIGAN 707 



The third paper was 



DRUMLINS OF MICHIGAN 

 BY ISRAEL C. RUSSELL 



[Abstract] 



Studies of a drumlin area in the northern peninsula of Michigan, a brief 

 report concerning which was presented at the last winter meeting of this 

 Society, have been continued and additional facts obtained that strengthen 

 the conclusion previously advanced in reference to the drumlins referred to 

 having been produced by ice erosion of a previously deposited till sheet. 



A contour map of a characteristic group of drumlins was exhibited, which 

 illustrated one of the several classes of irregularities presented by the drum- 

 lins of Michigan. In certain instances they depart from the normal shape 

 and have a straight, steep slope on one side. Drumlins showing this asym- 

 metry are thought to have been complete and symmetric in form at one time, 

 but later were partially removed by ice erosion. In the case of one of the 

 examples represented on the map referred to, about one-half of a drumlin, cut 

 parallel with its longer axis, appears to have been removed. 



Attention will also be invited to the smooth surface concave troughs which 

 occur between adjacent drumlins, and in numerous instances are as character- 

 istic features of drumlin topography as the similarly smooth, convex hills 

 they separate. Such "drumlin troughs" are thought to furnish criteria for 

 recognizing the effects of ice erosion in moraine and till covered regions, where 

 the correlative convexities are absent or but poorly defined. 



Certain of the drumlins of Michigan are composed of sandy till which is 

 without foliation, while other examples consist of definitely laminated clayey 

 till. The foliation appears to be due to pressure, and is present or absent 

 according to the nature of the material. 



The fourth paper was 



THE LEFROY, A PARASITIC GLACIER 

 BY WILLIAM H. SHERZER 



[Abstract] 



At the head of the Lake Louise valley, Canadian Rockies, lies the Victoria 

 glacier, which receives from the southeast a tributary somewhat over a mile in 

 length and from one-third to one-half mile in width. This tributary proves 

 to be double, the Lefroy being superposed on the Mitre and moving across it at 

 right angles. The parasitic Lefroy is formed from the ice and snow ava- 

 lanched from the eastern shoulder of mount Lefroy, and carries across the 

 Mitre the ground morainic material manufactured beneath the hanging glacier 

 on mount Lefroy. This material is dumped on the eastern margin of the 

 Mitre glacier, by which it is delivered to the Victoria as though it had come 

 from mount Aberdeen. The discovery of this relation of the Lefroy to the 

 Mitre glacier explains the direction of the dirt zones, the presence of the 

 ground morainic material in the right lateral of the Victoria, and its arrange- 



