326 CENTRAL MINERAL REGION OF TEXAS. 



Range for this rugged row of basic hills, as a token of esteem for my friend 

 and chief, the State Geologist of Texas. A very prominent landmark for many 

 miles at the eastern border of the greenstone, at its intersection with the axial 

 Burnetan strike of the main range, and which seems also to be crossed by the 

 east-west strike of porphyry, is most fittingly denominated Branner's Peak, 

 as a compliment to Dr. J. C. Branner, the State Geologist of Arkansas, an 

 area in which these three trends (approximately) are also well exhibited. This 

 eminence stands like a beacon upon the outer wall, towering alone above its 

 neighbors, which are all of earlier origin. A similar peak, the highest point 

 in the Dumble Range, I would respectfully dedicate by name to Mr. Robert 

 T. Hill, my colleague, as a slight memento of his brilliant career as a working 

 geologist in the vast regions adjoining the "Wichita Mountains in Texas, 

 Arkansas, and Indian Territory. Hill's Peak is likewise near the meeting 

 point of the Ouachita and Cretaceous uplifts, and thus it is fitly chosen to 

 honor one who has ably worked in those fields. 



It should have been stated that the Texan outcrop in the Wichitas is ex- 

 actly in line with the main exposures in Llano and Mason counties. 



The Silurian trend, north 25 degrees east, is not absent either from the 

 Wichita Mountain System. Admirably is the parallel with our district car- 

 ried out, even to the two features of striking interest, viz. : (1) the occurrence 

 of schist enclosures in granitic rocks, and (2) the repetition of the Texan and 

 Fernandan strikes in joint- courses. 



The granite here is somewhat more porphyritic, and the inclusions are at 

 times altered to blotches of actinolite and other basic minerals with a coarsely 

 crystalline texture. But there are different portions of the exposures in which 

 the whole appearance is very decidedly similar to our Honey Creek outcrops 

 in Llano and Mason counties. 



The confirmation of the repeated or continued action of orographic move- 

 ments into Silurian times which had begun much earlier is well brought out 

 in the western part of the Wichitas, where the relations of the joints can 

 often be studied to better advantage than in Central Texas. Beginning, so 

 far as my observations go, at a point about eight miles east of Branner's 

 Peak, where the schist-including granites outcrop, the Silurian trend is very 

 prominent in the joints of the inner or northern system of elevations. In 

 the neighborhood of Branner's Peak there are what we may style boulder 

 peaks of tough granitoid porphyry, which seem to belong to the Burnetan 

 axis in part, but which are also posed about little elevated flats of lacustrine 

 origin in such a manner as to suggest a crater of ancient date. The great 

 gap in the mountains west of this, and the continuation of this same topog- 

 raphy on" to the south-southwest in an undoubted Silurian uplift, leads me to 

 regard this as an important geologic feature of Silurian type modifying a 



