

CASS COUNTY AND PART OF CROW WING, 1899. WARREN UPHAM. 



tained in it, retaining the coarser portion which the current was not powerful enough 

 to transport. On the melting of the glacier the gravel ridge shows where the stream 

 was located during the prevalence of the ice, and the swampy tract along either side 

 shows the thinner drift sheet from which the clay was carried away and the gravel 

 was concentrated to form the ridge. These long ridges graduated, near the ice 

 border, into knobs and broken hills of little or no regularity of form or direction. 

 This happened where the water from the glacier border was not collected into 

 streams of considerable size but flowed down from the ice all along more evenly. 

 Where thei'e was not sufficient water to wash the drift the modified till was deposited. 



N. H. W. 



