GEOLOGY OF SOTJTHWESTEKN IOWA. 297 



counties just named are drained by tributaries of the Missis- 

 sippi river. It will thus be seen that the watershed which 

 divides the drainage of the two great rivers, passes through 

 these three counties. The highest land in the region, however? 

 is not along this watershed, but in Adair county and south- 

 ward, as shown in a previous chapter. Railroad levelings 

 show that the broad ridge which passes southward through 

 Adair, Union, and Ringgold counties, where it constitutes one 

 of the secondary watersheds only of the tributaries of the 

 Missouri river, averages about one hundred and fifty feet 

 higher than the ridge which divides the drainage of the two 

 great rivers. It will be seen then, that this region has two 

 principal surface slopes, both of which, however, are very 

 gentle. One of these is to the southwestward, and the other 

 a little east of southward. The first named is much the 

 largest, and is drained wholly by the tributaries of the 

 Missouri river, while the latter is drained by tributaries of 

 both great rivers. 



The natural wealth of this region, as at present actually 

 known, consists of its remarkably fertile soil, its limestone, 

 its water, wood, and to a slight extent, also, of its coal. 

 Besides the very small quantity of coal thus far discovered, 

 there is, as explained on previous pages, good reason to 

 hope that abundant supplies of that indispensable article 

 may be obtained in almost all parts of the region, by sinking 

 shafts of considerable depth down to the coal-bearing forma- 

 tions, which doubtless extend entirely beneath it by direct 

 continuity from the region along the Des Moines valley where 

 they occupy the surface. The other resources will be men- 

 tioned under the head of each county, but the different kinds 

 of soil being so uniform in their distinctive characters over 

 large areas, sometimes comprising several counties without 

 appreciable change, will be referred to further only in 

 general terms, while for more specific descriptions, the reader 

 is referred to the chapter on soils. In that chapter, three 

 distinct kinds of soil are described, . all of which occupy 



large areas in this region, and all of which are very fertile. 

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