240 THE GEOLOGY OF MINNESOTA. 



[Topography . 



any one of the formations, being disturbed only by an occasional thicken- 

 ing in the loam under circumstances favorable for its preservation, and by 

 a very gentle dip in all the strata toward the southwest. The uplands in 

 the eastern and northern portions of the county are from three hundred to 

 four hundred feet above the adjoining valleys, and near to the Mississippi 

 they are about five hundred feet above the grade of the Chicago, Milwaukee 

 and St. Paul railway. In the central portions of the county the uplands 

 are from fifty to seventy-five feet lower than in the eastern, and they would 

 be still lower if the drainage forces had been enabled to act there as effect- 

 ually as along the Mississippi, to carry away the surface loam. This is due 



FIG. 7. ROCKS NEAR HOMER. 



to the dip of the rocks from the Mississippi westward. Toward the west, 

 however, other higher formations make their appearance, and the actual 

 level of the uplands along the southwestern border of the county is about 

 one hundred feet higher than along the Mississippi. Plate 9 represents 

 Winona county. The tortuous contour-lines sufficiently indicate the uneven- 

 ness of the general surface, and also the gradual ascent of the upland prai- 



