An Arizona Mesa. 



7 



season, the temperatures at which time are about the same as 

 those at the lower altitudes, i. e., 2400 feet for the early spring 

 months. 



AN ARIZONA MESA. 

 By J. C. Blumer. 



The high Tertiary mesa that lies between Riggs and Bonita 

 Canyons is in its physiography typical of a number of similar 

 areas in the Chiricahua Mountains of southeastern Arizona. 

 Dipping very gently westward its surface is not entirely even, 

 but lies in gently rolling ridges with sharp troughs between, 

 that deepen toward either canyon into very precipitous side 

 canyons often lined with perpendicular pillars of rock hundreds 

 of feet high. Especially along Bonita Canyon these pillars are 

 chiselled by the tooth of time into a multitude of colossal forms 

 that present to the eye a picture at once beautiful in its symmetry 

 and bewildering in its massiveness. The very steep slopes 

 hundreds of feet in height and the precipitous rim that surround 

 this tableland or terrestrial island lend a charm to its explora- 

 tion perhaps second only to the setting foot upon an unknown 

 island in the sea. Upon scaling the rim of this plateau at an 

 elevation of about 7000 feet, it was a surprise to find conditions 

 very different from the half expected basalt and adobe, with a 

 grama-covered expanse openly dotted with yucca and alligator 

 juniper, which had greeted the eye on similarly formed New 

 Mexican mesas of the same elevation. The rock was a white, 

 disintegrating rhyolite, the soil rather meagre and coarse, and 

 the vegetal covering a more or less open pine forest densely 

 re-enforced by cypress brake and chapparal. In fact, the great 

 difference was only second to that between the floras of the 

 mesa and the adjoining limestone, which cannot be detailed 

 here. In a jaunt of about five miles no less than 13 woody 

 species were encountered. 



Of these manzanita (Arctostaphylos pungens) is the most 

 typical and abundant shrub, making a dense, low chapparal on 

 south, west, and intermediate aspects and on "hog-backs." On 

 bare rocks it spreads out close to the ground and covers its feet, 

 as it were. This is its characteristic habit on barren soil. Some- 



