LIGHT, AIR, AND COLOR 



91 



topaz-yellow, sapphire-blue, bright lilac, rose- 

 red yes, fire-red. During the heated months of 

 summer such colors are not exceptional. They 

 appear almost every evening. I have seen at 

 sunset, looking north from Sonora some twenty 

 miles, the whole tower-like shaft of Baboqui- 

 vari change from blue to topaz and from topaz 

 to glowing red in the course of half an hour. I 

 do not mean edgings or rims or spots of these 

 colors upon the peak, but the whole upper half 

 of the mountain completely changed by them. 

 The red color gave the peak the appearance of 

 hot iron, and when it finally died out the dark 

 dull hue that came after was like that of a 

 clouded garnet. 



The high ranges along the western side of 

 Arizona, and the buttes and tall spires in the 

 Upper Basin region, all show these warm fire- 

 colors under heat and sunset light, and often in 

 the full of noon. The colored air in conjunc- 

 tion with light is always responsible for the 

 hues. Even when you are close up to the moun- 

 tains you can see the effect of the air in small 

 ways. There are edgings of bright color to the 

 hill-ridges and the peaks ; and in the canyons, 

 where perhaps a sunshaft streams across the 

 shadow, you can see the gold or fire-color of the 



