194 MINNESOTA BOTANICAL STUDIES 



16), but studies have gone far enough that we may now chart with 

 approximate accuracy the limits of the main region of sandhills as 

 it occurs in this state. Obviously it is a mistake to include within 

 sandhill areas stretches of land characterized by widely isolated 

 sand ridges and ranges of low sandhills because the greater area of 

 such tracts is not composed of dune material but is of a firmer, finer 

 texture and should therefore be included in other soil regions. 

 Parts of Holt and Chase counties with much agricultural land have 

 been treated in this manner. In Dundy, Chase, and Hayes coun- 

 ties there are areas with conspicuously sandy soils, but there is little 

 else to remind one of the typical central sandhill conditions. Even 

 the occasional blow-outs of Dundy County are profoundly modified 

 because of a considerable admixture of hard material with the sand 

 that results in the development of low spires, domes, tables, and 

 other bizarre land forms where such soils are eroded by wind and 

 water. Even with a very conservative estimate of the total sand- 

 hill area of Nebraska at 18,000 square miles this means that we 

 have as much as 11,520,000 acres of this sort of land within our 

 borders. 



Prominent sandhills are known to occur over the trans-Missis- 

 sippi country in Kansas, Colorado, Nebraska, and the Dakotas. The 

 largest single area is to be found north and west of the central por- 

 tion of Nebraska. This main body of sandhills is oblong in shape 

 with its longer axis parallel with the east and west axis of the state 

 and with a center in Thomas and Hooker counties. The margin is 

 very irregular especially toward the eastern limits of the region. 

 The frontispiece map will convey at a glance the position of this 

 main body of hills as well as portray its relative area and form. Be- 

 sides the main sandhill region there are numerous other much 

 smaller areas of sandhills found in various parts of the state. Some 

 of these minor regions exhibit certain vegetative and topographic 

 characters that resemble those features of the main body, but as a 

 rule such isolated areas are considerably different as to vegetational 

 and other surface features. The more important examples of such 

 outlying areas are to be found in Perkins, Chase, Dundy, Hayes, 

 Lincoln, and Sioux counties as well as at a few small stations near 

 the Platte River farther eastward. Some of the smaller sandy areas 

 are to be included with phytogeographic subdivisions quite different 

 from the typical sandhills. 



