22 FIELD OPERATIONS OF THE BUREAU OF SOILS, 1918. 



subsoils, in most places free from mottling but here and there faintly 

 mottled with gray. The subsoil is heavier than the surface soil, 

 though generally containing considerable sand or gravel. Small 

 rock fragments are in most areas present throughout the 3-foot 

 section, and iron concretions occur in the subsoil. The topography 

 is for the most part rather rough. The Lindloy soils are naturally 

 forested. 



The terrace soils are thought to l)e derived from alluvial materials, 

 capped with a thin veneer of loess." Those along the Iowa and Cedar 

 Rivers are supposed to have been built up at the time of the lowan 

 ice invasion, while those along the Mississippi River, in the north- 

 eastern corner of the county, represent deposits from the drainage 

 waters of the Wisconsin ice.'' The soils on the terraces are grouped 

 in four series, namely, the Bremer, Buckner, Waukesha, and Calhoun. 



The soils of the Bremer series are black and underlain by gray to 

 black, heavy-textured subsoils, mottled with drab and yellowish 

 brown. The subsoils are as heavy as the surface soils, or heavier, 

 to a depth of 3 feet or more, and in the heavier members of the series 

 are tough and plastic. In their natural state the drainage is fair 

 to poor. The series is distinguished from the Wabash in lying above 

 overflow. 



The Buckner series includes brown to dark-brown surface soils 

 underlain by lighter colored, friable subsoils, having a texture similar 

 to that of the soil. These types are composed of reworked loessial 

 material frequently mixed with sediments from glacial and residual 

 soils. The drainage is good and occasionally slightly excessive. 



The Waukesha soils are dark brown to black and underlain by a 

 light-brown to yellow, friable subsoil. The latter, wliile heavier 

 than the surface soil, is not compact or impervious. The Waukesha 

 soils are naturally well drained. 



The members of the Calhoun series have gray to grayish-brown 

 surface soils, and a gray or drab, heavy clay subsoil. The latter is 

 tenacious, waxy, and impervious, and generally contains iron con- 

 cretions. In places the substratum consists of sandy material. 

 The Calhoun soils occupy poorly drained, or what were at one time 

 poorly drained, flats. While they lie above overflow, water generally 

 stands in the hollows after rains, owing to the impervious nature of 

 the subsoil. Many of the areas occupied by these soils are naturally 

 forested. 



The first-bottom soils consist of alluvium deposited in compara- 

 tively recent times by the streams they adjoin. They include two 

 series, the Wabash and Cass, and in addition the miscellaneous 

 types of Muck and Riverwash. 



« Geology of Louisa County, by J. A. Udden, Iowa Geological Survey, Vol. XI, I'JOi, p. 113. 

 ' Idem, pp. 113-114. 



