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EXPLANATION OF PLATES 



Plate I 



Map of tlie region studied. The sand ridges or islands are stippled ; the sandy- 

 loam flats or ancient stream channels appear as unshaded areas between the 

 ridges. 



Plate II 



Fig. I. A bunch-grass pasture at the Devil's Hole. A large blowout is partly 

 shown in the background; and to the right of it is shown a dune, 

 partly blown away, indicating the former level of the area now occu- 

 pied by the blowout. 



