THE GLACIAL FEATURES OF THE ST. CROIX DALLES 



REGION 1 



ROLLIN T. CHAMBERLIN 

 The University of Chicago 



Lying partly in Wisconsin, partly in Minnesota, this region has 

 claimed the attention of the surveys of both states and is covered in 

 their reports by general descriptions, in common with the adjacent 

 regions. Because of their clearness and grasp of the salient points, 

 the accounts to be found in Vol. Ill of the Geology of Wisconsin 

 relative to the main movements of the Superior glacier in the north- 

 west section of that state, form an excellent introduction to a detailed 

 study of the St. Croix Dalles quadrangle. The Kewatin glacier, 

 whose drift barely crosses the river into Wisconsin, has fallen to the 

 Minnesota geologists to investigate. The differentiation of the glacial 

 deposits of the last epoch into the red and gray drift, whose upper, 

 oxidized portion is spoken of as the yellow till, appears in the works 

 of Winchell 2 and Upham 3 . More recently a part of the Dalles 

 quadrangle has been subjected to a closer, detailed investigation by 

 Dr. Berkey, 4 who describes, among other aspects of the Pleistocene, 

 the two drifts, the erosion of the St. Croix channel, and the river 

 terraces. In that article the view of the Minnesota geologists, that 

 the ice-sheet of the red drift advanced across the region from the 

 northeast, is entertained. 



The topography of northern Wisconsin, in so far as it was molded 



1 My first acquaintance with this region was made as a member of the field class 

 of Dr. W. W. Atwood in July, 1904, at which time the views of Dr. Berkey, and the 

 Minnesota geologists, relative to the formation of the red drift by a movement 

 from the east, and of the gray drift by a movement from the west, and related inter- 

 pretations, were assumed to be correct, and made the basis of our working hypotheses. 

 At the close of the work, however, some of the interpretations were unsatisfactory. 

 After spending an additional month in further study under a wider range of alternate 

 hypotheses, I have reached the conclusions set forth in this paper. 



2 N. H. Winchell, Geology of Minnesota, Vol. I, p. 126. 



3 Warren Upham, ibid., Vol. II, pp. 399-425. 



4 C. P. Berkey, American Geologist, Vol. XX (1897), pp. 345-83. 



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