420 THE GEOLOGY OF MINNESOTA. 



[Elevations. Soil and timber. 



following elevations from the United States engineer corps. Its highest 

 Hoods rise about 25 feet above this line. 



Minnesota river, low wati i . 



Feet above 

 the sea. 



At the northwest corner of Blue Earth county, about 778 



At Judson 760 



At South Bend and the mouth of the Bl ue Earth river 756 



At Mankato .". 7">i> 



At the line between Blue Earth and Le Sueur counties, about 71:; 



At the points of crossing the boundary of the county, the elevation of the Watonwan river 

 is about 960 feet; of the Blue Earth and Maple rivers, about 990; and of the Le Sueur river, about 

 1010. The hights above the sea of the various townships of the county, excepting their portions 

 which have been deeply excavated by rivers, are approximately as follows: Lime, the terrace of 

 limestone in the west part of the township, reaching about two miles easterly from the Minnesota 

 river, 820 to 840, and the remaining two-thirds, east from the top of the bluffs, 980 to 1020; 

 Jamestown and Le Ray, 1000 to 1060; Mankato, 975 to 1020; South Bend, plateaus between the 

 valleys, 960 to 990; Judson and Cambria, 975 to 1000; Butternut Valley, 980 to 1020; Lincoln and 

 Garden City, 990 to 1020; Rapidan, 975 to 1000; Decoria, 990 to 1040; McPherson, Medo, and 

 Danville, 1025 to 1075; Beauford and Mapleton, 1000 to 1040; Lyra. 975 to 1025; Veruon Center 

 and Ceresco, 1000 to 1040; Sterling and Shelby, 1010 to 1060; and Pleasant Mound, 1025 to about 

 1100. The southwest part of the last named township, which is the most southwestern of this 

 county, appears to be the highest portion of its entire area of flat or gently undulating drift; and 

 the kames, or irregular hillocks and short ridges of gravel and sand, in section 25 of this town- 

 ship, rising 30 to 75 feet above the adjoining region, and approximately 1100 to 1150 feet above 

 the sea, are the most elevated points of land in Blue Earth county. These hillocks are thus about 

 400 feet above the lowest land of the county, in the valley of the Minnesota river. 



The mean elevation of Blue Earth county is 1,000 feet, very nearly, above 

 the sea; but would be 1,025, without the reduction for its eroded valleys. 



Soil and timber. The soil of this county is uniformly very productive, 

 and is well adapted for all crops which can be cultivated in this latitude. 

 Though the land is mostly level or only slightly undulating, it is yet 

 so intersected with water-courses that nearly all portions are well drained, 

 giving opportunity for early sowing and planting, and preventing damage 

 to crops by heavy rains. At the surface is a stratum of black earth usually 

 about two feet, but varying from one to four feet in depth. It is clay, 

 with more or less intermixture of sand and gravel, and including occa- 

 sionally a stone or boulder of considerable size. Its black color has been 

 produced by the decay of vegetation through all the years since this de- 

 posit was spread here in the ice age. The subsoil is the same glacial clay 

 or till, without this organic matter, and of light yellowish-gray color to a 

 depth of ten or twenty feet, below which it is darker and bluish. This dif- 

 ference has been produced by water and air, which to these depths below 

 the surface have changed the carbonate of iron in this formation to the 



