THE PEAIEIES XJl 



tion of available records and observations in the field indicates 

 that a little more than seven-eighths of the surface was prairie, 

 leaving less than one-eighth for the forest area, which, however, 

 included the thickets bordering streams, and the scrub-oak thick- 

 ets in various parts of the state, which should scarcely be digni- 

 fied by being called forests. 



The prairie was very variable in topography, for it occurred 

 in alluvial vallej's, upon flat drift plains, on abrupt slopes, — 

 indeed upon all tj'pes of topography in the state from the flat- 

 test to the most broken.^ Neither was it restricted to particular 

 geologic formations, for it was found, and still exists to a limited 

 extent in its primitive condition, upon every kind of formation 

 which reaches the surface, not only in Iowa but in the entire 

 ^Mississippi valley. 



In the upper Mississippi valley typical prairie is found lying 

 over all the older rocks from the Algonquin to the Cretaceous; 

 on all the drift areas from the Xebraskau to the Wisconsin ; on 

 loess of every horizon : on alluvial flats ; on sand-dune areas ; and 

 on the limited areas in which geest forms the immediate subsoil. 



On Murray hill northeast of Little Sioux, Iowa, Aftonian sand 

 and gravel are exposed along the basal third, Kansan till and 

 Loveland joint clay occupy the middle of the slope, and loess 

 forms the surfaces of the uppermost two-fifths, yet the flora is 

 essentially the same from base to summit so far as the species 

 are concerned, upon the portions of the surface having the same 

 exposure. The only noticeable difference appears in the vigor 

 and size of the plants, those on the Aftonian surfaces being 

 stunted and less densely crowded. 



Among scientific observers the problem of the prairie has 

 usually been assigned to. or assumed by, the geologists, and Dana, 

 Whitney, White, Alexander Winchell. N. H. Winchell, Foster, 



2The latter was published by Baker, jSTative and Planted Timber in 

 Iowa, Forest Service Circular, 154, U. S. Dept. Agr., Sept. 15, 1908, p. 8. 



3lt included territory which varied from the comparatively moist bor- 

 ders of swamps, lakes and streams, to the highest, dryest ridges of loess 

 or drift. Indeed, drainage or absence of water had little to do in deter- 

 mining its distribution, for it frequently extends to the very border of 

 swamp, or stream, or lake, extending alike over areas of very unequal 

 drainage. 



