4 8 



FARM DEVELOPMENT 



few hundred feet of the present site, when they were 

 first discovered by the European explorers, and named 

 the Falls of St. Anthony. From comparisons of descrip- 

 tions and drawings made by the earliest explorers, and 

 pictures taken at later dates, it seems that these falls 



receded at the 

 rate of several 

 feet per year, or 

 that the falls re- 



ceded e 

 miles in 



ight 



about 

 ei ht 



BBiUMUTOM 



Figure 11. A, surface of water in the Minnesota river in - 



glacial times when it received the water from the valley of tilOUSanQ 

 the present Red River of the North. B, surface of the water . 



in the Mississippi river in glacial times when it flowed gently I hlS has 

 into the well-filled channel of the Minnesota river, X, the 



limestone. Y, the layer of sandstone below. thought bv 



to very roughly mark the date when the glacial dam was 

 melted low enough to allow the waters of the valley of 

 the Red River of the North, then the "Ancient Lake 

 Agassiz," to flow northward into the Hudson Bay and 

 no longer swell the banks of the Minnesota River, which 



began to shrink to a ( _ 



small stream in the bed 

 of the old river. 



In 1871 it was found 

 that the Falls of St. 

 Anthony, beside which 

 a number of flour and 

 saw mills had been 

 erected, were in dan- 

 ger of being under- 

 mined and washed out. The water had broken 

 through crevices in the lime rock, which was thin, 

 and was wearing away the soft sandstone beneath. 

 As this would have caused the falls to recede 

 very rapidly, and to become a mere rapids, destroy- 

 ing the valuable water power, the United States 



Figure 12. The Falls of St. Anthony when Us 

 recession had just begun. A, water in the Min- 

 nesota, after it had ceased to receive the 

 glacial water. B, water in the Mississippi river 

 above the falls. C, water in the Mississippi 

 river below the falls. D, the Falls of St. An- 

 thony when yet at a point near the confluence 

 of the two rivers. 



