4(5 '2 THE GEOLOGY OF MINNESOTA. 



[Glacial lake. Moraines. 



by settlers on its east side) lies in the east part of township 98, and in sec- 

 tions 3, 4 and 9, of township 97, range 38, its length being about eight 

 miles in a course first south and then south-southwest. Its width is from 

 one-eighth to one-fourth of a mile, with enclosing bluffs which rise steeply 

 twenty to thirty feet to the general surface of moderately undulating till 

 on each side. The bottom of this glacial channel along the Union slough, 

 where its descent was southward, is now mainly occupied by a marsh, 

 because of the partial filling up of its continuation, since the ice age, by 

 Buffalo creek. Along the head-stream of the Blue Earth river, from 

 Union slough to the state line, this channel has a width of about an eighth 

 of a mile, and is twenty-five to thirty feet below the average surface at 

 each side, to which the ascent is by moderate slopes. 



This valley, eroded by outflow from the glacial lake of Faribault and 

 Blue Earth counties, soon changes upon the smoothed area covered by that 

 lake to channels eroded since the glacial period by the present drainage. 

 Thus the excavation by this branch of the Blue Earth river in Elmore is 

 thirty to forty feet deep, and has steeper banks, but is narrower, than the 

 valley in which it lies farther south. Northward, the lacustrine area, 

 otherwise a vast plain, has become deeply eroded by the Blue Earth river 

 and its tributaries. 



Moraines. Exceptions to the generally smooth and nearly level con- 

 tour of the drift are found in two rolling and hilly tracts, one in the eastern 

 half of the county, the other on its southern edge. The most conspicuous 

 elevations, in this part of the state are the drift hills in Kiester township. 

 This tract is closely joined with the inner or western of the two approxi- 

 mately parallel terminal moraines, which extend from north to south 

 across Freeborn county, and which were accumulated at the east side of 

 the vast lobe of the ice-sheet that in the last glacial epoch covered the 

 basin of the Minnesota river and reached south to central Iowa. The drift 

 upon this ice-covered area was left with a very smooth, slightly undulating 

 surface, while its borders are marked by morainic belts of hilly and knolly 

 drift. These hills in Kiester appear to indicate that the ice-margin here 

 became indented by a re-entrant angle between two confluent ice-currents. 

 Northwest from Kiester, a belt of hilly or more or less rolling drift reaches 

 twenty miles, to the southwest part of Lnra; and ten miles beyond appears 



