VVINONA COUNTY. 251 



St. Peter sandstone.] 



lating outward between the loam and the shales. It is frequently the case 

 that wells on this plateau reach water fifteen to thirty feet below the sur- 

 face, while on the lower prairies adjacent, it is necessary to drill more than 

 100 feet, or even 200 feet, in order to get water for domestic uses. 



The St. Peter sandstone. This formation in Winona county has an aver- 

 age thickness of somewhat less than one hundred feet, though no exact 

 measurement of it has been made. It affords frequent surface exposures in 

 the slopes of the bluffs that outline the area of the Trenton, and also occa- 

 sionally is seen by the roadside at points some miles from that line of bluffs. 

 In situations similar to the latter, but of course at lower levels, the Jordan 

 sandstone is also frequently seen, and might very easily be mistaken for the 

 St. Peter, since the Shakopee limestone, which separates them, is reduced 

 to about twenty-five feet in the western part of the county, and probably to 

 less than twenty-five feet in the eastern part. The formation lies nearly 

 level throughout the county, and conformably on the Shakopee limestone, 

 so far as observed. To this statement only one exception must be made, as 

 already mentioned under the head of Trenton rocks. About a mile south 

 of St. Charles the St. Peter has a noticeable dip of about six degrees toward 

 the south-southwest, and is apparently unconformable with the Trenton. It 

 cannot be asserted positively that this dip involves all of the Cambrian, but 

 there are some reasons for believing that it does, and that the great anti- 

 clinal that enters the county between Dresbach and Richmond in a general 

 west-southwest direction is deflected toward the west-northwest within the 

 county, Root river and its tributaries draining the southward dipping strata 

 and the Zumbro the northward. The river bluffs at Elba are remarkably 

 high, a fact which may be owing to the dip seen in the St. Peter south of 

 St. Charles, affecting the whole Cambrian and throwing the St. Lawrence 

 and Shakopee higher above the sea in the region immediately to the north 

 from St. Charles. 



The sandy knolls in sec. 12, Saratoga, have no limestone on their tops, 

 but their contour and elevation, as they now exist, are preserved by a cem- 

 ented rusty layer which is about eighteen inches thick and lies on the west- 

 ern slopes in large fallen-down blocks, being kept uncovered on that side 

 by the prevailing western winds. It is probable that they exist in a similar 

 manner on all sides of these mounds, but are hid by the loam. These knolls 



