BLUE EARTH COUNTY. 419 



Elevations.] 



age. The river, after excavating its valley through this sheet of glacial 

 drift, found a channel in the underlying rocks which was eroded before the 

 ice age. That it was not made in the recent epoch, seems to be proved by 

 the fact that its bordering walls of rock, varying from one fourth of a mile 

 to at least two miles apart, are through long distances concealed by drift, 

 which alone forms one or both sides of the valley. The depth of the pre- 

 glacial erosion was considarably bslow the present river, as is shown by 

 the boring for an artesian well at the top of the river-bluff in Mankato, 

 where the bed-rock was reached at 290 feet, or about 65 feet lower than 

 the river. 



Elevations. The following hights have been determined by railroad 

 surveys within this county; the reference, unless otherwise stated, being to 

 the track at depots. 



St. Paul & Sioux City diviiion of the Cliicago, St. Paul, Minneapolis & Omaha railway. 

 Copied from profiles in the office of T. P. Gere, superintendent, Saint Paul. 



Miles from Feet above 

 St. Paul. Hie sea. 



Mankato, - 84.0 791 



Blue Earth river, low and high water. 86.2 753-774 



Blue Earth river, bridge, - 86.2 795 



South Bend. 87.6 808 



Minneopa bridge, 68 feet above water, 89.2 863 



Minneopa, 89.4 871 



Summit, grade, 95.6 992 



Lake Crystal, 97.3 994 



Summit, grade, - 102.2 1009 



Iceland, 104.1 998 



Winona & St. Peter division of the Chicago & Northwestern railway. 

 From John E. Blunt, engineer, Winona. 



Miles from Feet above 

 Winona. the sea. 



Eagle Lake, - 122.56 1012 



MankatD Junction, 127.99 906 



Mankato, - - 131.00 781 



Mankato branch of the Southern Minnesota division, Chicago, Milwaukee & St. Paul railway. 

 From George B. Woodworth, assistant engineer, LaCrosse. 



Miles frim Feet above 

 l.a Crosse. tlie sea. 



Mapleton, 161.4 1031 



Maple river, -water, - 168.5 935 



Good Thunder, 169.3 974 



Rapidan, 175.6 979 



Le Sueur river, water, 772; bridge, - 177.9 825 



Crossing St. Paul & Sioux City railroad, 181.3 795 



Mankato, - 182.5 770 



The low-water slope of the Minnesota river descends 35 feet, approxi- 

 mately, along the north side of Blue Earth county, according to the 



