18 



Game Survey of the North Central States 



Agricultural Belt. All counties in the Agricultural Belt are over 50 per 

 cent farmed, and most of them consist almost entirely of improved farms con- 

 taining not to exceed 25 per cent of woodlots, swamps, bluffs, or other "rough" 

 lands. 



The five types in this belt differ from each other in their proportion of orig- 

 inal prairie, and in the origin of their soils. 



The prairie type contained no timber except along streams, hence its present 

 upland timber is scanty and limited to artificially planted or escaped species. The 

 soil is deep, rich, and black. The glaciated parts originally contained many 

 swamps and lakes, most of which are now drained. In the unglaciated parts 

 swamps were confined to bottoms. The streams are muddy. The prairie type 

 was the home of the prairie chicken. Parts of it now support pheasants, and 

 parts a few quail. 



The type here called "riverbreaks" was originally hardwood timber, inter- 

 spersed with an infinity of prairies, large and small. The degree of this inter- 

 spersion may be judged from Map 2 and 2a. 



MAP 2: Interspersion of Original Prairie and Timber in Iowa (compiled by B. Shimek). 



By comparing these with Map 1 it will be apparent that the boundary between 

 the riverbreak and prairie types has been arbitrarily simplified. The predominant 

 riverbreak soils are yellow loess, and grayish clays. Evidences of glaciation are 

 weak, or have been covered by the loess blanket. Erosion is frequently active. 

 Old gullies stabilized by brush are characteristic of this type. Its original timber 

 is now of course largely cleared. It may be distinguished from the prairie type by 



