84 THE BROAD-SCLEROPHYLL VEGETATION OF CALIFORNIA. 



represent extreme youth. Wider ravines with graded floors approach 

 maturity, and extensive base-leveled areas with occasional monad- 

 nocks have reached old age. With such a series it is an easy matter 

 to correlate vegetational development with physiographic age. 

 Invariably upon the flat surfaces of the terraces and uneroded 

 remnants the vegetation is well-developed chaparral, in which 

 Adenostoma is commonly dominant, either solid or represented 

 by relict masses. Chaparral covers the newer base-leveled areas 

 also, except where streams have recently coursed over them. In 

 other words, the stable areas, which have had a chance for a relatively 

 long period of vegetational development, support the chaparral 

 community. Further, the composition of the vegetation of oldest 

 terrace-tops and youngest base-levels is practically identical. Since 

 the terrace-tops, with their vastly greater age, have not advanced 

 beyond the stage reached by the recent base-levels, it is plain that 

 that stage is the climax. 



The species that inhabit the unstable eroding slopes and the 

 recently formed washes make a very diff'erent assemblage. They 

 are mainly short-lived half-shrubs which germinate readily and are 

 able to exist in the unfavorable conditions which such habitats offer. 

 Clements (22) regards this well-marked community as the western- 

 most association of the sagebrush formation, because of the impor- 

 tance in it of Artemisia californica, and gives it climactic rank. 

 His appellation is here tentatively accepted. The area of coastal 

 sagebrush dominance has not been accurately determined, but 

 roughly it covers the plains and low interior valleys of southern 

 California from the Santa Ana Range to the San Jacinto Mountains. 

 Within the climax chaparral it is successional, occurring in both the 

 primary and secondary series. A number of the species extend 

 northward for varying distances, a few as far as the San Francisco 

 Bay region. 



A list of the most important species follows, those particularly 

 characteristic of the southern California group being marked with 

 an asterisk (*) : 



Eriogonum fasciculatum.* Ramona stachyoides. Baccharis pilularis. 



Syimatium glabrum. Sphacele calycina. Encelia farinosa.* 



Helianthemum scoparium. DiplacuB glutinosus. Eriophyllum confcrtiflorum. 



Malacothamnus fasciculatus.* longiflorus. Lepidospartum squamatum.* 



Ramona clevelandi.* punioeus.* Artemisia californica. 



nivea.* Ericameria pinifolia.* Senecio douglasii. 



polystachya.* 



Two or three brief descriptions of individual localities will be of 

 interest. The eroding southwest slope of Smiley Heights, apparently 

 a remnant of an ancient fan, near Redlands, is steep and unstable. 

 The species are Eriogonum, Encelia, Ramona stachyoides, and Arte- 

 misia. The bluff is much dissected into gullies and ridges which 



