410 



THE GEOLOGY OF MINNESOTA. 



I Geological structure. 



which attains a width of one to one and a half miles at the east side of this 

 stream in the southeast part % of Wilton and the adjoining edge of Otisco. 

 Southwest from the Le Sueur river, the flat expanse which reaches thence 

 to the limits of the county is prairie, and its green mat of grass sometimes 

 bears no tree nor bush within an area several miles in extent. The lakes, 

 however, within this tract are usually bordered by wood, and belts of 

 timber mark the course of its streams. 



White and slippery elm, bass, sugar and red maple, box-elder, black and 

 bur oak, butternut, white and black ash, ironwood, wild plum, Juneberry, 

 American crab-apple, common poplar or aspen, cottonwood, and willows, 

 are the principal species of trees in this county. 



GEOLOGICAL STRUCTURE. 



No outcrop of the strata underlying the drift occurs in Waseca county, 

 but they have been reached by wells at three localities. One of these wells, 

 reported by Prof. L. B. Sperry, "near Janesville, after passing through 200 

 feet of blue clay, reached a sandstone said to be identical with the St. Peter 

 in appearance. An abundance of good water, which rose to within 30 feet 

 of the surface, was found between the clay and the sandstone." 



At the town of New Richland, a well at Dunwoody & Corson's mill 

 reached a depth of 110 feet, finding the following section: soil, 2 feet; 

 yellow till, with streaks of sand, yielding water, 30 feet; blue till, softer and 

 sticky, 66 feet; sand, 2 feet; and hard, straw-colored sandstone, 10 feet. At 

 this depth water was struck, and rose in two minutes to 30 feet below the 

 surface. Another well at this mill, 149 feet deep, drilled by Mr. C. E. 

 Whelpley, is reported by him to be drift, 107 feet; yellow calcareous sand- 

 rock, 40 feet; and similar rock of blue color, 2 feet. A very large supply 

 of water was obtained, rising to the same hight as the last. The well 

 at the depot, about forty rods north of the foregoing and on land of the 

 same hight, is 129 feet deep, and found the soil 2 feet thick; yellow till, 

 spaded, 10 feet; blue till, mostly very hard, picked, 115 feet; and yellowish 

 sandstone, similar to that of Dunwoody & Corson's well, 2 feet and extend- 

 ing lower. Water, found in this sandstone, rose 80 feet. It is noteworthy 

 that the top of the bed-rock in these wells, only an eighth of a mile apart, 

 differs about 25 feet in hight, probably on account of erosion in a formation 



