WICHITA MOUNTAINS. ' 325 



The great northwest, or Fernandan, trend of our district is also represented 

 in the Wichita Mountains, but in a way which suggests obscured deposits or 

 outbursts of readily denudable material along the mid-course of the chain. 

 West of the point where the Carlton Mountains seem to be stopped by the Bur- 

 netan axis of the Wichitas, about twelve miles from Fort Sill on the Navajoe 

 road, there is a broad dyke, or spur, of granitic porphyry not unlike some of 

 the Fernandan irruptives of Central Texas. This is badly broken by joints of 

 the later trends, but the northwest strike is discernible and the general course 

 of the rugged outcrop is maintained for a number of miles. This line of low 

 peaks forms a prominent topographic and geologic landmark not heretofore 

 recognized at its true value. Strictly speaking, it is not a part of the main 

 Wichita range, but a subordinate uplift, checked in its progress by the older 

 axis, as in the case of the much more modern Carlton Mountains. In honor 

 of the chief of the Comanches, whose range is in this neighborhood, the 

 name of Quanah Mountains is proposed for this sub-range. 



There are suspicions that certain gaps in the Burnetan axis, at intervals 

 along the chain, have been caused by this later Archaean upheaval. The 

 evidence is often obscured by the Post-Paleozoic sediments, but the present 

 disposition of the compound axial ridges of the Wichita System is such as to 

 frequently cause one to travel northwest to cross the chain through the gaps 

 from the south to the north side. At the intersection of the Burnetan and 

 Fernandan trends there are topographic features in the shape of peaks and 

 passes which are of a distinctive type. West of this for twenty miles the 

 Burnetan axis presents a determined front to the south, as if free from break 

 by important orographic movements, although the joints of the later trends 

 are usually discernible, and a special expression of the northeast course is 

 evident in certain places, besides an interesting development of the Post- 

 Silurian uplift. 



The Texan, or north-south, trend is characterized by what is probably the 

 type of Dr. Shumard's "greenstone porphyry." It is a green basic porphyry 

 of coarsely crystalline texture, which is referred to by Dr. Hitchcock at page 

 146 of Marcy's report. This is associated with a complex rock of similar 

 character, studded with little patches of magnetite, and the whole set probably 

 occupies a belt fifteen miles in width, although this is now largely covered by 

 Tertiary and Quaternary deposits. Along its western border, however, it has 

 resisted denudation, and now forms a well marked mountain chain independ- 

 ent of the Wichita-Burnetan axis. Some portions of these outlying ridges can 

 not be so easily explained, and there is reason to believe that an expression of 

 the Ouachita uplift, or east-west trend, is in some way represented. To eluci- 

 date these points in detail, such accurate topographic work as we have done in 

 the Central Texas area will be absolutely necessary. I suggest the name Dumble 



