328 CENTRAL MINERAL REGION OF TEXAS. 



the base of Branner's Peak, at the divide between West Cache Creek and 

 East Otter Creek; the other including the tough dark gray material of the 

 Dumble range, which is also visible as a dyke cutting through Branner's 

 Peak. Some of this resembles the Little Rock syenite in a general way, but 

 this may be only superficial. 



Some veins of quartz of the east- west trend have been observed near the 

 Dumble range and elsewhere. 



The latest uplift of the north 50 degrees east trend is clearly illustrated by 

 joints which break all the others. In places between the crossings of the 

 earlier outbursts, the Burnetan rocks have been so riddled by this dynamic 

 movement as to present the appearance of loose rock piles, and some of the 

 same ancient outcrops which now peep through the thick Tertiary and Quar- 

 ternary deposits southward are even arranged in lines corresponding to this 

 latest upheaval. The only typical rock of this uplift, here clearly shown to 

 Pre-Tertiary (if the Fort Sill Beds be Tertiary), is a trachytic red lava, no- 

 where occurring in great quantities, but chiefly existing as dykes and low 

 hills in the upper valley of Otter Creek. 



There are numerous minor relations of an intimate character which bind 

 together the two regions we are discussing, which have evidently been com- 

 panions in development through the eons of geologic time; but enough has 

 been given to prove that from the earliest Archaean to the close of the Paleo- 

 zoic their history has been practically the same, although different in degree 

 of igneous activity. 



