DRUM LIN, OSAR AND KAME FORMATION. 259 



some qualifications and exceptions. This conclusion is not at all 

 new, for, as is well known, it has been reached by several stu- 

 dents of these phenomena quite independently. But an approach 

 to the question along the line of evidence presented by bowlder 

 belts and bowlder trains has its own advantages. It bears particu- 

 larly upon a new view of the origin of drumlins recently advanced 

 by one of our most experienced glacialists in which they are held 

 to have been chiefly formed from englacial drift which "had 

 become superglacial by ablation and was afterwards enclosed as a 

 stratum within the ice-sheet, being thence amassed in these hills."' 



In the midst of the drumlin area of south-central Wisconsin, 

 there arise from beneath the Paleozoic strata a few scattered knobs 

 of quartzite and quartz-porphyry from which erratics have been 

 derived and borne away to varying distances, constituting bowl- 

 der trains of the most definite type. These are radically different 

 from the bowlder belts discussed in my previous paper. The 

 quartzite outcrops near Waterloo, in Jefferson County, are the 

 most favorably situated for the purposes of the present study, 

 because they are right in the heart of the most pronounced drum- 

 lin area and have made large contributions to the erratic content of 

 the drumlins themselves. My associate, Mr. I. M. Buell, has been 

 engaged for some time in a very careful study of the abrasion 

 which these quartzite outcrops suffered from glaciation and of 

 the distribution and special relationships of the erratic material 

 derived from them. The drift movement was here to the south- 

 southwestward and quartzite blocks derived from these outcrops 

 enter in great abundance into the constitution of the drumlins 

 lying in that direction. Several features of their distribution and 

 nature are worthy of special note. 



I. The quartzite bowlders are not simply scattered over the 

 surface of the drumlins, but are distributed throughout their 

 entire mass so far as accessible to observation. As the drumlins 

 bear evidence of gradual accretion, it seems necessary to suppose 

 that they were built up by successive additions of featerial 



"' Conditions of Accumulation of Drumlins," Warren Upham, Americaji Geolo- 

 gist, December, 1892. pp. 339-362. 



