RED MOUNTAIN, ARIZONA 



145 



entered through a narrow gorge. This gorge is not commonly occu- 

 pied by a stream, but its form is such as to indicate that it was made 

 by running water. Within the gateway the excavation in the moun- 

 tain broadens out into an open amphitheatral form, and serves as 

 an immense funnel concentrating the waters which fall on that side 

 of the mountain. 



Fig. 6. — Looking east in Red Mountain, showing numerous pillars and mounds 

 which have resulted chiefly from rain erosion. 



The erosion-forms in the amphitheater resemble those common 

 to bad lands. There are narrow winding passageways which end 

 as box canyons; on projecting spurs there are sharp pinnacle-like 

 forms capped with angular lava blocks; the walls are decorated 

 with strangely irregular forms, and marked by great pits where 

 large masses of lava have been weathered out. To the west (Fig. 5), 

 the layers come out clearly near the base, but higher on the slopes 

 they are indistinct. To the east there are numerous pillars and 

 mounds in various stages of development (Figs. 4 and 6). Some of 

 the pillars are just being separated from the main mass of the moun- 



