400 THE GEOLOGY OF MINNESOTA. 



[Terminal moraines. 



of the ice, probably followed by a re-advance, took place between the time 

 of accumulation of the eastern or outer belt of hills and hillocks and that 

 of the inner, western member of this twofold formation. 



In this county the eastern morainic belt extends through Merton, 

 Havana. Aurora and Blooming Prairie, its eastern range of townships. It 

 occupies the greater part of Merton, at the northeast corner of this county; 

 but its hillocks, mounds or swells are only from twenty to thirty and rarely 

 forty feet high. Most of them consist of till, or drift clay, enclosing boul- 

 ders: but here and there are mounds of irregularly stratified fine gravel and 

 sand. The east third of Havana has a similar rolling surface, bordering 

 the west part of Rice lake. Through Aurora this moraine is well exhibited 

 in scattered mounds and' hillocks, fifteen to forty feet high. On the road 

 from Owatonna to Blooming Prairie and Austin, it is crossed in sections 

 I), 15 and 22. being here about three miles wide. At Aurora station and for 

 one and a half miles south, this formation is finely seen at the east side of 

 the railroad, by which it is crossed in section 28. The boundaries of the 

 moraine are very definite in this township. Its narrowest place in the county 

 is found in section 28, north of which it is indented on the northwest side 

 by a tract of lowland and marsh, which lies next west of the railroad, 

 reducing the width of the hilly tract to one mile. At the west and south- 

 west this quickly widens again to two or three miles, covering sections 29, 

 30, 31, and 32, of Aurora, and sections 25 and 3(i of Somerset, with a profu- 

 sion of knolls and hills, twenty to fifty feet high, sprinkled with boulders, 

 principally granite and gneiss, mostly less than two feet in diameter, with 

 occasional blocks or slabs of limestone, sometimes six or eight feet long. 

 These elevations are seldom prolonged more than a few hundred feet. The 

 trend of their longer axes is more frequently from east to west than other- 

 wise, but this is not very noticeable. From the southeast corner of Somer- 

 set the moraine turns southward, and extends in typical hills and short 

 ridges through the west two ranges of sections in Blooming Prairie. Here 

 the trend of its separate elevations is most frequently from north to south, 

 being parallel, as before in its east and west trends, with the course of the 

 whole series. In the west part of sections 8 and 17, Blooming Prairie, these 

 rough hillocks are well exhibited, being twenty to fifty feet above the depres- 

 sions, and seventy-five or one hundred feet above the neighboring creek. 



