NO. 10 



SMITHSONIAN EXPLORATIONS, I923 



79 



Fig. 74. — The Clay Hills extend southward to the Rio San Juan as an 

 unscalable barrier of red and gray shale, overtopped by sheer walls of pink 

 sandstone. ( Photograph by E. L. Wisherd. Courtesy of the National Geo- 

 graphic Society.) 



Fig. 75." — ^When Moki Canyon cut its tortuous course, massive caves were 

 formed at every angle and in these caves prehistoric peoples sought refuge 

 from the elements and from their tribal enemies. (Photograph by E. L. 

 Wisherd. Courtesy of the National Geographic Society.) 



