PLATE XIII. 



DODGE COUNTY, 1884. M. W. HARRINGTON. 



The valleys in the northeastern part of Dodge county, cut in the Lower Silurian, 

 are the westward vanishing extension of those of Olmsted county. The rest of 

 the county is a uniform and nearly flat prairie where the streams wander about on 

 the surface of the drift, having excavated but insignificant depressions, and occa- 

 sionally expand into swampy lakelets. The highest parts of this prairie are south 

 of Dodge Centre, something over 1,300 feet. The lowest points in the county are in 

 the valley of the Middle Branch of the Zumbro, about 1,000 feet. On the highland 

 prairies, especially along the shallow basins occupied by the small streams and 

 lagoons, are frequent large granite boulders, sometimes twenty-five or thirty feet 

 long, constituting a marked natural exception to the prevailing monotony. These 

 are not confined to this county, but are met with also in Mower and many other 

 counties. They attest the former activity of some powerful transporting agency 

 from the northern and central parts of the state, the nature and relative date of 

 which, amongst the varied drift forces, have not yet been sufficiently elucidated. 

 The drift consists essentially of a tenacious blue clay with stones, probably largely 

 augmented by debris from the Cretaceous, but toward the northeast this blue clay 

 seems to fade into a yellow loam. 



The Trenton limestone (or Galena) is quarried at Mantorville, and red brick are 

 made at Dodge Centre and Kasson. The county is a typical one of the upland 

 prairies of the southern part of the state. N. H. w. 



