AITKIN COUNTY, 1899. WARREN UPHAM. 



thrust across the Mississippi valley further south, causing the. flooding of much of 

 the region of the Upper Mississippi in Aitkin and Cass counties. This was probably 

 later than the existence of lake Agassiz. 



The level of the water of Mille Lacs was formerly about fifteen feet higher than 

 at present, as evinced by distinct beach ridges at that hight, seen on the north side 

 of the lake. This may have been due to a glacial expansion from the same ice-lobe, 



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shutting off the Rum river outlet at about the same time that lake Aitkin was formed 

 by the obstruction of the Mississippi; or, as suggested by Mr. Upham, this beach 

 ridge may be found to be submerged, or merged into the present beach by greater 

 differential elevation toward the north, should it be traced carefully toward the south. 

 If it was a glacial lake there may be found, perhaps, an outlet westward into the 

 Mississippi river through the Nokasippi valley. N. H. w. 



