368 



THE GEOLOGY OF MINNESOTA. 



[Drainage. Water-power. 



basins to receive the drainage from a large tract of country, and when 

 they become full discharge successively into each other until their volume 

 is sufficient to maintain a continuous stream. The water-shed between 

 the sources of the Zumbro and the Cedar is very broad and flat, and from 

 its summit the horizon fades out before the beholder in the dim, blue dis- 

 tance so gradually, that unless the air be clear it is difficult to distinguish 

 it either to the north, south or west. This divide consists immediately 

 of drift, as indicated by large boulders along the shallow drainage lines, 

 and by the excavations for wells. 



The fall of all the streams is inconsiderable in all parts of the county, 

 but greater in the northern part than in the southern. 



Water-power. The only improved water-power in the county is found on the middle and 

 north forks of the Zumbro river. The following list shows the location and manner of improve- 

 ment of these powers: 



Of the above mills tbat at Mantorville has two powers, one being about a hundred and ten 

 rods above the other. There is an unimproved mill privilege at Concord. 



The south middle branch of the Zumbro rises in Rice lake, which also has a natural outlet 

 toward the west into Straight river, through Maple creek. In order that the mills on the east- 

 ward-flowing stream should have as much water as possible, the western outlet was cut off. Still 

 the supply is so uncertain that the mills are compelled to stop some years during several months 

 in the winter season. The water in the north middle branch is still more unreliable. 



Topography. The surface is but little diversified. The southern and 

 southwestern portions of the county are an undulating prairie, with no 

 visible rock exposure, sometimes marshy, and but thinly settled. On some 

 of these high prairies are frequently seen large quantities of boulders. 

 They seem to prevail in the lower spots, and especially in boggy surfaces, 

 yet are not wanting on the upland prairies. Some are twenty-five or thirty 

 feet long, with corresponding width and hight. They are found all the way 

 fi'om a few miles south of Kasson to the Mower county line.* They con- 

 stitute the most marked natural exception to the monotonous features 



See the Mower county report. 



