VEGETATION OF BOX CANON. 



15 



both of the land and its plant covering, are only a phase in a 

 series of changes through which both have long been passing. 

 We are reading to-day only the last page that has yet been writ- 

 ten of a long-continued history still in progress. Is it possible 

 by any scientific method to gain some further knowledge of this 

 history? It must be answered frankly that without exact obser- 



FiG. 6. " The right side, directly opposite, was like a continuation of the 



desert." 



vations and records extending through a period of years, we 

 are not likely to make the most substantial progress, and it must 

 be added that even the application of such exact methods may 

 fail to bring a complete solution of the problems here presented. 

 Meantime some of the facts here recorded are suggestively open 



