The Ice-cftrrenfs of Minnesota— Ujyham. 51 



scale at the public water-works of Antwerp in Belo^iuni, whereby 

 a badly contaminated river water is said to be made thoroughly 

 wholesome. It is asserted that living germs as well as dead or- 

 ganic and inorganic matter are destroyed and removed from the 

 water. Perhaps the people of Minneapolis, and other populations 

 along the Mississippi, may in time avail themselves of such filter- 

 ing processes. Scientific authority tells us that we run great risk 

 in drinking water which has at any time been contaminated with 

 animal excreta unless we apply to that water the most thorough 

 methods of destroying organized microscopic impurities. The 

 people of Winona, for example, and the people of Hastings, would 

 run great risk of infection from impurities that enter the river at 

 Minneapolis and St. Paul, although chemical tests as at present 

 known and applied give the water at Winona and Hastings such 

 comparatively good credit for p:.rity. The best known methods 

 of purification may not remove all this risk. But it would be the 

 part of prudence to apply them when practica})le. 



James A. Dodgk. 



[Paper E.] 



<!HANGES IN THE (X'RKEXTS OF THE ICE OF THE LAST GLACIAL EPOCH 



IX EASTERN MINNESOTA. — Warreu Upham. 



Read before tlie Minnesota Academy of Natural Sciences, May 8, 1883. 



When the ice of the last glacial epoch attained its maximum ex- 

 tent, it appears that the ice-current moving southwestward 

 from lake Superior across the northeast part of Minnesota, spread- 

 ing a reddish till containing boulders and pebbles peculiar to the 

 region from which it came, had its limit at a line reaching from 

 lake St. Croix southwesterly across the Mississippi and through 

 the north part of Dakota county, thence bending to a northwest 

 direction and continuing by lake Minnetonka and through Wright 

 and Stearns counties . At the same time another portion of the 

 ice-slieet was pushed from the region of lake Winnipeg and the 

 Red river valley to\vard the south and southeast, meeting and op- 

 posing the ice-current from lake Superior along a line from 

 Stearns county southeast by lake Minnetonka to Crystal lake in 

 Dakota county: beyond which its eastern limit farther south was 



