190 THE LURE OF THE LAND 



State at about Cass or Bates County, and entering 

 Kansas in perhaps Miami County, thence northwesterly, 

 crossing the Kansas River in Riley County, entering 

 Nebraska at or near Jefferson County; crossing the 

 Platte probably at Polk County; thence northwesterly 

 to Holt County. West of the Mississippi River these 

 boundaries are ill-defined, and in all of the Western 

 States there are large areas where the soil is so modi- 

 fied by other influences that agriculturally its drift 

 character is almost wholly lost. 



" The second great class of soils occupies the undu- 

 lating parts of the country lying south of the drift. 

 They have been made by the decomposition of the 

 rocks which have occupied their present position. The 

 natural action of water, air, and the gases which they 

 contain, along with varying temperature, tends to dis- 

 integrate the rocks. Even the hardest will weather 

 in the course of time. Some decompose rapidly, others 

 more slowly, but all in such a climate as ours ulti- 

 mately will be reduced to a soil. The immediate sur- 

 face disintegrates more rapidly in a cold climate, where 

 frost aids the process, but ultimate chemical decompo- 

 sition goes on more readily in a warm climate than in 

 a cold one, particularly if it have abundant rains. If 

 a region is fertile and the climate favorable, so 'that 

 there is an abundant vegetation on the surface, which 

 produces carbonic acid and other solvent products by 

 its decay, the decomposition goes on more rapidly be- 

 neath. If the underlying rocks are of limestone, then 

 large quantities of the lime are dissolved, and if the 

 limestones are impure, containing much insoluble mat- 

 ter, the solution of the soluble carbonate of lime leaves 

 a soil composed largely of the insoluble remains. Such 

 soils are often of extraordinary fertility, illustrious ex- 



