DAVIS: THE GRAND CANYON OF THE COLORADO. 



193 



the more striking things are here presented in the hope that they may 

 prove of service to more leisurely travellers. 



The dissection of Mt. San Francisco, as seen from the wagon road 

 that runs northward from Flagstaff along the western base of the 



Figl-re 1 



Diagram to illustrate a proposed terminology of spurs and ravines. Constructed from 

 several sketches of the western side of Mt. San Francisco, a dissected volcano. 



mountain, suggested a simple terminology for spurs and ravines that 

 might perhaps be serviceable in detailed descriptions of mountain forms. 

 The scheme is illustrated 

 in the accompanying fig- 

 ure, 17, which repeats some 

 of the features illustrated 

 in the diagram of the Per- 

 mian scarps (Figure 9). I 

 shall hope to return to 

 this phase of morphology 

 at some future time. The 

 young ash cones, still hold- 

 ing unbreached craters, 



were numerous in the volcanic field north of Mt. San Francisco (Fig- 

 ure 18). About ten miles west of Hull spring (on the Flagstaff-canyon 

 road) a large ash cone was seen with a great breach in its eastern 



Figure 18. 



An ash cone and crater, north of Mt. San Francisco 

 and east of Hull spring. 





