246 THE GEOLOGY OF MINNESOTA. 



[Soil. 



The Rollingstone valley in a fine one, especially in the month of July. 

 It is wide and smoothly contoured from the bluffs downward, the main flat 

 being the same terrace-plain as that already mentioned at and below Stock- 

 ton, gradually rising toward the west as the stream is ascended, and also 

 passing more abruptly into the slopes, right and left, which descend from 

 the enclosing bluffs. These slopes are cultivated well up the hillsides, as in 

 nearly all parts of the county, and raise oats, barley and even wheat and 

 corn, the more precipitous portions above being pasture fields. There is an 

 insensible change from the main flat to these slopes. The flat itself consists 

 of yellow loam, stratified where exposed in wash-outs along the road, but 

 in the upper slopes becoming gradually replaced by the coarser debris from 

 the hills, and toward Minnesota City becoming the great terrace which is 

 known to accompany the Mississippi all the way from St. Paul. Yet even 

 at Minnesota City it is still covered with a yellow loam of later date. 



At Pickwick the loam-clay that constitutes the terrace and forms the 

 subsoil, is seen to be interstratified along the bluff-side, near the mill, with 

 several layers of rotted debris from the bluff, with lenticular patches of reg- 

 ular stratification. The section here exposed is seen in fig. 9. 



FIG. 9. SECTION AT PICKWICK. 



In general throughout the county the loess-loam is clayey, and holds 

 the surface waters in all confined depressions. No stones of foreign origin 

 are found in it to obstruct the plow, or impede the reaper. Indeed it is 

 only in the neighborhood of St. Charles, in the western part of the county, 

 that the true northern drift is found in Winona county. Where it exists it 



