SANTA CATAI.IXA INIOUNTAINS. 251 



'I'lic ascent of Cusllc JJdck is iiiaJc frcmi liiis jxn'iit In ahoul 

 f<nii- hours. As lliere is iki I rail one lias to make his way as best 

 he can. For about a thousand iVet we passed along rocky ledges 

 bearing ver.v nnieli the same kind of vegetation that we find on 

 foot hills, the giant cactus, ocotillo, a species of acacia, palo 

 verde and Simondsia being the prevalent forms of larger size. 

 At the altitude of four thousand feet the sotol {Dasylirion 

 Wheceleri) becomes (pute abundant and the live oaks make an, 

 open forest on the more horizontal benches. The old flower 

 stalks of the sotol are the nesting places of a large carpenter bee, 

 which we often noticed flying in pairs. From this point on, the 

 clind) is rather severe, especially on account of the dense growth 

 of the small amole (Agave Schottii). We had to make about 

 a ihousand feet of steep, stony ridges, with scarcely anything 

 growing on them l)ut this ])lant. This part of tlie climb brought 

 us to the main ridge and to the tremendous outero[) of granite 

 rock whieli forms Castle Rock. The vegetation here ehanged 

 abruptly. 



The trees now consisted of juniper and nut pine {Pi mis 

 C emhroides) , interrupted by huge rounded rock masses and by 

 here and there a chapparal of manzanita. As we moved along 

 the rough ridges we passed from time to time deep chasms in the 

 northwestern face of the rock, extending to a depth of from one 

 to two thousand feet, sometimes in an almost vertical line. As 

 we gained the still higher altitude we found a species of Cereus 

 very similar in general appearance to the Cereus Fendlen of the 

 foothills. The flowers of this sjiecies, however, are of a more 

 eoreaceous texture, scarlet in color, with violet stamens. ^^\^ 

 brought some specimens of this plant back with us and succeeded 

 in l)rin2inc: them into flower after we returned to Tucson. We 

 foun<l also a few plants of a Yucca, probably Yucca radiosa, 

 and on the summit, bear grass, a few prickly pears. Agave 

 Schottii and Sotol growing together. 



The tip-top of Castle Rock is an almost flat area of per- 

 haps an acre in extent, clothed with large-sized junipers and 

 pines, under which there is a deep vegetable humus. The north- 



