CHAPTER XI El. 



THE GEOLOGY OF BLUE EARTH COUNTY. 



BY WARREN UPHAM. 



Situation and area. Blue Earth county (plate 16) lies in the central 

 part of southern Minnesota, being in the second tier of counties north of 

 Iowa. Mankato, its largest town and the first in size within the basin of 

 the Minnesota river, is distant about 70 miles, measured in a straight line, 

 southwesterly from Minneapolis and Saint Paul. The length of this county 

 from east to west is five townships, or 30 miles, and its breadth from north 

 to south varies from 21A to 29 miles, being least through the center of the 

 county, from South Bend, and greatest upon its western boundary line. 

 The Minnesota river separates this from Nicollet county. After Mankato, 

 the towns and villages of most considerable size are Lake Crystal, Garden 

 City, Vernon Center, Good Thunder, Mapleton and Eagle Lake. The area 

 of Blue Earth county is 776.88 square miles, or 497,201.73 acres, of which 

 21,619.39 acres are covered by water. 



SURFACE FEATURES. 



Natural drainage. This county lies wholly within the basin of the 

 Minnesota river, which at South Bend and Mankato turns from its south- 

 east course and thence flows northeastwardly almost at right angles with 

 its upper portion. The drainage from the greater part of Blue Earth 

 county, as also of Waseca, Faribault, Martin, and Watonwan counties, is 

 discharged into the Minnesota by the Blue Earth river, which has its mouth 

 about one mile west of Mankato. The slopes of this county and the courses 

 of its drainage descend from three sides, east, south and west, toward the 

 middle of its north side. In general the county is to be described as a 



