SOILS, ETC. 127 



Although the greater part of the drift of Iowa is composed 

 of materials that are fitted to produce good soil, it should be 

 stated that the portion which now occupies the first few 

 feet beneath the surface is in much the best condition for it, 

 and that the surface is almost everywhere free from the 

 coarse drift materials, being usually occupied by the finer 

 portion alone. Consequently the soil is almost everywhere 

 line and excellent, even when the drift beneath, as is some- 

 times the case, contains much sand and boulders, and in 

 other cases stiff clay. It should be also borne in mind that 

 even where the boulders are most abundant, they are not 

 sufficiently so as to interfere with agricultural operations, nor 

 to impair the value of the land for agricultural purposes. 



2. BLUFF SOIL. 



The bluff soil, as its name denotes, is that which rests upon 

 and constitutes a part of the Bluff Deposit before described. 

 The description of that deposit is really a description also 

 of the soil, for with the exception of the accumulation of 

 humus in it at the, surface; it is perfectly homogeneous from 

 top to bottom, even where it is more than two hundred feet 

 thick. Neither does it vary materially in composition with 

 geographical extension, as will be seen by Prof. Emery's 

 analysis of specimens of it obtained from different localities ; 

 there is, therefore , no proper distinction between the soil and 

 subsoil of the region it occupies. The area occupied by this 

 soil is the same as that occupied by the Bluff Deposit, 

 described on previous pages. In Iowa, it is found only in the 

 western part of the State and adjacent to the Missorui river, 

 and may be said to contain a superficial area within the State 

 amounting in round numbers to about five thousand square 

 miles. This bluff soil grades imperceptibly into the some- 

 what similar drift soil to the eastward of it, but as a whole it 

 presents a marked contrast with all the other soils of the 

 State, and occupying as it does, so large an area, its peculiar- 

 ities are well known and easily recognized. Although, as 



