COTTON WOOD AND JACKSON COUNTIES. 495 



Topography. } 



36, Germantown. In the central and southwest part of Amboy and the east half of Storden, this 

 highland, besides slowly increasing in elevation westward, expands to a greater width, and forms 

 an approximately level plateau of till, one to three miles wide, with outcrops of the quartzyte only 

 upon the slopes which descend from it. The most southern exposures of this rock in Cotton- 

 wood county are in the west part of sections 6 and 7, Dale, and in section 12, Amo, on the west- 

 ern descent from the most southern part of this plateau, which here in northwestern Dale is 75 

 or 100 feet above the remainder of this township and its Three lakes, and about 150 feet above 

 lake Augusta on the west. 



This area of Potsdam quartzyte is the only part of Cottonwood county which has exposures 

 of the bed-rocks, the remainder being moderately undulating or rolling and sometimes hilly gla- 

 cial drift. The general slope, as already stated, rises from east to west, and at the west side of 

 Amo and in Rose Hill this drift attains as great an altitude as the quartzyte range eight miles 

 northeast in Amboy and Stordon. 



The townships of Westbrook, Ann, Highwater and Germantown, lying north of this hight 

 of land in Eose Hill, Amo and the ridge of quartzyte, ha've mostly a smoothly rolling contour, 

 with the crests of swells fifteen to thirty feet above the depressions. The creeks which drain 

 this district northward to the Cottonwood river flow in valleys that they have eroded 20 to 40 

 feet beiow the average surface. 



The whole of Jackson county, like the northwest and south parts of 

 Cottonwood county, is so deeply covered by the glacial drift that it has no 

 outcrop of the underlying rocks. Southwest and south of the quartzyte 

 ridge, these counties are crossed by a belt of knolly and hilly or promi- 

 nently rolling morainic drift, two to seven miles wide, which reaches from 

 Rose Hill southeast to the Blue mounds west of Windom, and thence south 

 through the center of Jackson county to the west side of Spirit lake. From 

 the vicinity of Windom a branch of this moraine extends ten miles north 

 through the west part of Lakeside and Carson. The same knolly and bro- 

 ken contour of the drift is found also in the south part of Sioux Valley and 

 in Round Lake township, on the southwest border of Jackson county. 

 Excepting these morainic tracts and the ridge, of quartzyte, these counties 

 are a smoothly undulating, and in part almost flat, sheet of till, ascending 

 with a very gentle slope from east to west, enclosing lakes here and there 

 in its depressions, slightly channeled by creeks and deeply cut by the Des 

 Moines river. Many further details respecting the contour of the drift are 

 presented in a later part of this chapter. 



The valley of the Des Moines river in South Brook, the most southwest township of Cotton- 

 wood county, is less distinct in its outlines, and its depth is less, than in any other part of its 

 extent below lake Shetek. South Brook has mostly a rolling contour of massive swells, variable 

 in their forms, trends, and extent, rising 20 to 50 feet above the Des Moines river, which flows 

 among them in an irregular course, generally without any well-defined valley of bottomland and 

 bluffs, but turned here and there by small undulations. In section 19 it passes through the north 

 end of Talcott lake, which lies in a shallow basin of the drift-sheet, covering nearly a square 

 mile, but only from five to eight feet deep. 



In Springfield where the Des Moines flows northeast, at right angles to its course both above 

 and below, it again occupies a definite valley, channeled 50 to 75 feet below the average hight of 



