4 SOILS OF THE EASTERN UNITED STATES. 



northern Indiana there are portions of the type which were heavily 

 wooded before they were cleared for agricultural occupation. In all 

 of the more western areas, however, it constituted a prairie type 

 whose surface was dotted only along the margins of shallow lakes 

 and along the stream courses by clumps and narrow lines of trees. 



SURFACE FEATURES AND DRAINAGE. 



The surface of the Carrington loam in all of the regions where 

 it occurs is remarkably uniform. The greater part of the type is 

 only gently undulating or slightly rolling, although low ridges 

 and lines of hills, consisting of glacial moraines, not infrequently 

 cross the area of the type, giving it locally a somewhat rolling to 

 slightly hilly surface configuration. There are no marked -differences 

 in altitude between the lower and the more elevated portions of the 

 type in the majority of the areas where it occurs, and generally 

 the extreme range of altitude within the limits of this type in a 

 single county is not over a hundred feet. Owing to the undulating 

 or slightly rolling character of its surface there are not infrequently 

 to be found small depressed areas, occupied by swamps or ponds, or 

 low swales without natural outlet. In the majority of instances 

 these depressions are composed of soils other than the Carrington 

 loam, but in some cases this type is also developed at these lower 

 altitudes. 



When the entire area occupied by the Carrington loam in the 

 North Central States is considered it is found that there are con- 

 siderable variations in the altitude of the type. Thus around the 

 lower end of Lake Michigan the elevations range from 650 feet to 

 about 800 feet above tide. In north-central Iowa and southern 

 Wisconsin the altitudes range from 1,000 feet to about 1,250 feet, 

 while in North Dakota the Carrington loam is found at altitudes 

 ranging from about 1,100 feet above sea level in the southeastern 

 part of the State to an altitude of 1,600 feet in its northern por- 

 tion. This difference in altitude, coupled with an accompanying 

 difference in climatic conditions, varies to some extent the char- 

 acteristic crops which may be grown to the best advantage upon the 

 type in the different locations where it is found. 



In general the natural drainage of the Carrington loam when it 

 was first occupied for agricultural purposes was somewhat deficient, 

 particularly in the more level and lower lying portions of the type. 

 In many instances the first necessity for the occupation of the ty 

 consisted in the construction of open ditches and the improvement 

 of these drainage conditions. In the more western regions of ii 

 occurrence, however, the drainage was fair to good, and the prairie 

 condition of the Carrington loam required only the breaking of 



