42 FIELD OPERATIONS OF THE BUREAU OF SOILS, 1918. 



areas now occupied by the type were formerly lakes or ponds, and all 

 the areas lie at a lower elevation than most of the surrounding types. 

 The greater part of the type lies near the upland or terrace bluff, but 

 in places it extends to the river and even occurs on the adjacent 

 islands. As the type, which is composed of the finest of soil particles, 

 could only be deposited in comparatively quiet water, it is probable 

 that the areas now close to the river were some distance back from 

 it when formed. Where not cleared the type is generally forested 

 and more or less cut up by sloughs. Wliere it occupies a former 

 lake or slough bed there is only a growth of coarse grasses. 



Unless protected by levees, this type is subject to overflow. It is 

 naturally poorly drained, but much of it has been, and probably all 

 can be, reclaimed by ditching and pumping the drainage water over 

 the levees. 



This is an extensive bottom-land type, and about one-half of it is 

 in cultivation at the present time. East of Oakville there is a large 

 area, comprising between 2,000 and 3,000 acres, the greater part of 

 which is in cultivation. North of the Iowa River and south of Port 

 Louisa is another large body, of approximately the same size, of 

 which only a very small part is cultivated. Corn is the principal 

 crop, timothy, wheat, and oats being grown to a less extent. With 

 good drainage, yields are practically the same as on the Wabash silty 

 clay loam. Where not cultivated the type is used as range for 

 cattle, hogs, and horses. As with the silty clay loam, care must be 

 taken not to work the land when too wet. The selling price has 

 practically the same range as in the case of the Wabash silty clay 

 loam. 



CASS SAND. 



The Cass sand is a dark-brown to brown medium sand 10 inches 

 deep; underlain by a lighter yellowish brown medium sand, passing 

 into a coarse sand containing some fine gravel. In places the subsoil 

 is less coarse than tj^^ical. One small area on the east of the Great 

 Sand Mound shows the effects of wind action. 



This type occurs in many rather small areas in the Iowa and 

 Mississippi River bottoms. It generally lies slightly higher than 

 the surrounding soils and is well drained. Where it is protected by 

 levees the greater part of it is cultivated, but the unprotected areas 

 are used chiefly for pasture. Corn, the principal crop, yields about 

 15 to 38 bushels per acre. 



A soil coarser than the typical Cass sand is included with it, on 

 account of the slight difference in texture and the small extent of 

 both types. It consists of a coarse sand throughout the 3-foot sec- 

 tion, but the color, which is dark brown to browTi in the upper part, 

 becomes slightly lighter and has a more reddish tinge with depth. 



