STUDIES IN THE DRIFTLESS REGION OF WISCONSIN 



In my previous articles under the above title I have stated 

 that no glaciated material had up to that time been found. 

 Indeed I was not very hopeful that any would be found, for not 

 only are the beds concealed to a very large extent, but the parts 

 exposed are those which would naturally be composed of super- 

 o-lacial and englacial material. Add to this the fact that the 

 glaciers if really prescribed, were but a few thousand feet long 

 at the utmost, and the further fact that even of this short dis- 

 tance a considerable portion was over loess of earlier deposition 

 and it will be seen that such material must necessarily be scanty. 

 Nevertheless in view of the extreme difficulty of determining the 

 original aspect of the beds in many important particulars it was 

 very desirable that the evidence which could be furnished by 

 glaciated material should be added to that already given. I 

 think it very fortunate therefore that during the past summer I 

 have discovered a bowlder which gives very strong if not deci- 

 sive indications of glacial abrasion, and inasmuch as it will form 

 a most important part of the evidence for the existence of 

 glaciers I will describe it in considerable detail. 



The bowlder lies at the bottom of a ravine, well within one 

 of the smaller valleys. It is about ioin.Xi4 in.X26 in. in 

 dimensions. The material is a rather hard, course-grained 

 ferruginous sandstone, such as occurs a little below the base of 

 the Lower Magnesian limestone. Its rather rough uneven sur- 

 face is the product of prolonged weathering, but at one end there 

 is a facet forming an irregular oval about 6 in.xS in. which con- 

 trasts strongly with the rest, being nearly flat, and very notice- 

 ably smoother to the touch. Examination with a lens shows 

 that this smoothness is due to the relatively small projection of 

 the individual sand grains, few standing out more than a third 

 of their diameter above the general surface, while on the 



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