3l6 n. W. JOHNSON VOLCANIC NECKS OF MT. TAYLOR REGION 



whatever. The circular benches of sediments are more likely due to the 

 pi'otective action afforded by the central cores of igneous rock rising well 

 alcove them and the accumulated talus of large lava fragments which are 

 sometimes found about the bases of the towers. 



jSTumher 6, Cerro Cochino (plates 26 and 28, and figure 8). This 

 butte is composed- of a very large bench or terrace of the horizontal Cre- 

 taceous sediments, from the top of which rises a shaft of igneous rock. 

 The right-hand butte shown in figure 21 of Button's report is evidently 

 Cerro Cochino. We made no detailed examination. 



jSTumber 7 (plate 28). Southeast of the Mexican village of Salazar is 

 a large hutte surrounded by horizontal sandstones and shales. The 

 hutte appears to be elongated in a north and south direction, although 

 we did not make a close examination. Just north of it, in Ihe side of 



FioiiRE 0. — Crnns-scctifiii shnioiny Cuntact of horizontal Sedhiteiitft with ifincoiis Core 



of Butte inimher S. 



... Precise contact covered with wash. 



Prieta mesa, there is evidence of a fault, the displacement being T5 feet 

 or more, as neaidy as we could estimate. 



Number 8 (figure 9). This is a medium-sized butte showing fine 

 columnar structure, the columns pointing in almost every direction, ex- 

 cept that no good vertical ones were seen. The sediments have been 

 stripped away from every side but the southeast, where they are seen 

 making a vertical contact with the igneous rock of the butte almost to its 

 summit. The beds remain horizontal. A small dike, a few feet in 

 width, can be traced from the butte a short distance northward. 



JSTumber 9. This butte contains a large proportion of agglomerate, and 

 as seen from a distance appears to be somewhat elongated in a north- 

 south direction. Small hummocks are seen at intervals southward 

 toward Great neck ; these luimmocks nuiy be minor buttes similar to the 

 larger ones, or remnants of a dike; it" was not possible for us to visit 

 them. 



