210 Wisconsin Academy of Sciences, Arts, and Letters. 



more than half that amount, however, in crossing the vallej, as 

 the canon-like channel of the pre-glacial river, seems to have 

 been filled without much affecting the surface contour of the 

 drift. But the fact of undulation to conform to an irregular sur- 

 face, produced by erosion, and not by flexure of the strata, is a 

 point to be noted, as it is a serious obstacle in the way of any ex- 

 planation that is only applicable on the supposition that the for- 

 mation was in a horizontal position when formed, v-s the view that 

 it was produced by beach action, or the stranding of icebergs. 



After crossing Rock river, the range curves gradually to the 

 northward, passing over the watershed between the Rock and 

 Wisconsin rivers, " descends abruptly 200 feet into the low ground 

 of the valley of the Wisconsin,"^ crosses the great bend of the 

 river, sweeping directly over the quartzite ranges, according to 

 Prof. Irving, with a vertical undulation of over 700 feet, after 

 which it gradually ascends the watershed between the Mississippi 

 and St. Lawrence drainage systems, until its base reaches an esti- 

 mated elevation of 700 to 800 feet above Lake Michigan. From 

 thence it has been traced across the headwaters of the Wisconsin 

 river, by Mr. A. Clark, under my direction.^ 



Within the Chippewa valley, it has been observed by Prof. F. 

 H. King, of the A\isconsin Survey, and I have observed it in the 

 vicinity of the Wisconsin Central railroad. This region is cov- 

 ered by an immense forest, mainly unsettled and untraversed, even 

 by foot paths, so that geological exploration is difficult and ex- 

 pensive, and, as no industrial importance attaches to it, and the rock 

 below is deeply concealed by it, I have not deemed it sufficiently 

 important to trace the belt continuously to justify the large ex- 

 penditure of time and means requisite, especially as I entertain 

 no serious doubts as to its continuity and general position. The 

 observations made, indicate that it descends obliquely the east- 



1 Prof. Irving, Geol. of Wis., Vol. 11, 1877, page 616. 



' To the eastward of the range, as thus traced. Col. Whittlesey describes (Smithsonian 

 ContributloDs, 1866) a similar formation in Ocon'o county. I have observed the same at 

 eeveral points. Mr. E. E. Breed informs me that it occurs on the watershed between the 

 Wolf and Oconto rivers, but it has :not yet been traced throus;!! the wilderness, to any 

 connection with the main range, and It is uncertain whether it is so connected or constitutes 

 a later formation, as snch later moraines have been observed at other points. 



