The Alamogordo Desert 



157 



perhaps a thousand feet higher, surmounted by materials 

 correspondent with those in the level of the plain. On 

 the west the same thing is true; but more emphasized 

 still is the difference in level between segments of corre- 

 sponding strata. Here the weird Organ mountains 

 break the horizon by upthrust spires and pinnacles of 

 granite * which to some early voyageur crossing these 

 dusty plains suggested the pipes and architecture of 

 some far-off organ, and the mountains were so named; 

 but upturned granite means that the sedimentary rocks 

 are here further uplifted still than on the eastern side, 

 so that we quickly find ourselves in presence of vast par- 

 allel faults and our desert lies thus between their giant 

 walls. It is as if half the region between this city 2 and 

 New York should suddenly sink two or three thousand 

 feet, or, what is the same thing, it is as if the several 

 thousand feet of difference in level were brought about 

 by the depression of the included area, and the simul- 

 taneous elevation of the sides. At any rate the desert 

 plain of the Alamogordo or Tularosa sands is simply the 

 upper surface of a gigantic block of the earth's crust 

 that sank some time subsequent to the deposition of the 

 Jura-Trias and the earlier cretaceous strata of this west- 

 ern world. These strata include, as we know, the famous 

 "red beds" which tinge the mountains of half the con- 

 tinent, the red beds with all their gypsum, marls, and 

 salts of every description. Accordingly, as a result of 

 this faulting, our desert has for its foundation every- 

 where great fields of gypsum, often for long distances 

 wide-exposed, sometimes thinly veiled by loosened sand, 



1 So reported. *' ' 



2 Philadelphia. 



