APPENDIX D. GEOLOGY. 147 



distance. But taking all the facts into the account, I cannot but feel 

 that there is reason to presume that volcanic agency has been active in 

 that region more recently than the trap dykes. 



I ought to add, that before reaching the Witchita mountains Dr. 

 Shumard met with large quantities of dark-colored and cellular igneous 

 rock, composed principally of silex and carbonate of lime, strewed over 

 the surface. This was on the 18th of May, and on the 27th he "fre- 

 quently encountered local deposites of red, scoriaceous rock." Anions; 

 the specimens in my hands are some apparently more or less melted, 

 composed of carbonate of lime and copper ore. 



Again, scattered widely over the surface, numerous specimens were 

 found of jasper, carnelian, and agate. The carnelian is deep red, but 

 found in botryoidal, or even stalactitical masses, and they have seemed 

 to me to resemble more those silicious nodules found in soft limestone 

 than in trap rocks. They were found most abundantly towards the 

 western part of the region gone over. 



I ought to have mentioned that the Witchita mountains consist of 

 numerous peaks, rising from eight hundred to nine hundred feet above 

 the river. Mount Webster, one of the most conspicuous, was found to 

 be *783 feet above the plain by the barometer. Twelve of these eleva- 

 tions were found to be composed of granite, which in many places is 

 undergoing rapid disintegration. 



We have seen in the red clay of this region a reason for the name of 

 Red river, and the character of its waters. In the above description 

 of the rocks of the Witchita mountains, I think we may see the origin 

 of the red clay. The great amount of iron which they contain would 

 produce exactly such a deposite upon their decomposition and erosion 

 by water. And we have reason for supposing this red granite to be a 

 quite extensive formation, as I shall shortly show. 



No one at all acquainted with the rocks in which gold is found can 

 look at the specimens you have obtained in the Witchita mountains 

 without expecting that he shall be able to detect that metal. The por- 

 phyry, the porous quartz from veins impregnated with hydrate of iron, 

 and the magnetic iron-sand found in the btd of Otter and Cache creeks, 

 excite this expectation. In one of your letters you state that " the peo- 

 ple of Texas have for a long time supposed that there was gold in the 

 Witchita mountains, and they have attempted to make several examina- 

 tions for the purpose of ascertaining the fact, but have invariably been 

 driven away by the Indians. We searched diligently about the mount- 

 ains, but could find only two very minute pieces imbedded in quartz 

 pebbles." This, as Dr. Shumard states, was upon Otter creek, and there 



