OOTTONWOOD AND JACKSON COUNTIES, 1884. WARREN UPHAM. 



There are several old drainage courses in these counties, probably formed in 

 interglacial time, and during the last retreat of the ice-margin. They bear signifi- 

 cant relations to the morainic tracts. The Des Moines river once went into Heron 

 lake and thence into the valley of the Little Sioux river and to the Missouri valley. 

 On the retreat of the ice the Des Moines crossed the main morainic belt and entered 

 an ancient valley which was perhaps pre-glacial and turned southeastward in it, 

 forming the "big bend." This pre-glacial valley is excavated, apparently, in some 



f 



rocky formation, but shows only drift in its bluffs. Below Jackson it is about 100 

 feet below the brink of the bluffs. Two old water-courses are seen in Germantown, 

 north of the quartzyte plateau, trending southeastward, probably formed during the 

 departure of the last ice-sheet. N. H. w. 



