South Dakota School of Mines 



Bulletin No. 9. Plate No. 17. 



Photograph by O'Harra. 1909. 

 Figure 1. Sun-cracked surface of an alluvial flat showing loosening and curling of the drying mud. 



Photograph by O'Harra. 1909. 



Figure 2. Spongy surface of Titanothevium clay showing ease of disintegration. 



