414 



peterson. PROBLEM OF GULLYING 



[Ch. 23 



Fig. 1(a). View upstream near head of 

 the San Simon gully, Arizona. 



Fig. 1(6). Badlands developing adjacent 



to San Simon gully, Arizona. Main 



channel not shown. Note brush and 



rock spreader in left foreground. 



Fig. 1(c). Erosional unconformity ex- 

 posed in walls of San Simon gully, Ari- 

 zona. Top layer is brown silt, bottom 

 layer is pinkish gray clay. 



