WICHITA MOUNTAINS. 327 



Burnetan volcanic focus. Branner's Peak is almost certainly of later origin. 

 The Silurian expression in the southwest, along the valley of West Otter 

 Creek, is a beautiful exponent of the great geanticlinal of Post-Silurian date. 

 No sedimentary beds have been observed as involved in this uplift, but the 

 west branch of Otter Creek flows through an anticlinal ridge of the granitoid 

 porphyry. The trend of this uplift is indicated well in the relief, and nearly 

 all the maps give the facts fairly, although few of them are good for the 

 Wichita Mountains as a whole.* 



The sketch map of the region which is given on the Section Sheet accom- 

 panying this Report gives such a representation as will enable any one to 

 locate the peaks to which names have been given herein. 



To the series of knobs which lie along West Otter Creek Valley, east and 

 north of the North Fork of Red River, opposite the Navajoe Mountains, I 

 have given the name Blanche Mountains, as a tribute to my wife. 



The Blanche range, if prolonged in its strike, would cross Texas west of 

 the Central Mineral Region; and Mr. Dumble informs me that there are indi- 

 cations of such a structure in that area, which will receive close attention 

 later. 



The Navajoe Mountains, an isolated but elevated ridge upon the west bank 

 of the North Fork of Red River, in Greer County, represent the crossing of 

 severals of the uplifts, being hardened erosion relics similar to some of the 

 remnants in Llano County. 



The Post-Carboniferous, or Ouachita, uplift has already been described. 

 The east-west trend is prevalent everywhere throughout the range. Carlton 

 range has no exact counterpart, so far as I have determined, but there are 

 ridges of dolerytic material and dykes of basic character for the most part, 

 which certainly belong to this system. These occur, as stated, near Branner's 

 Peak, in the Dumble range, especially near Hill's Peak, and in places along 

 the northern edge of the Wichita chain. f 



It seems probable that Shumard has confounded in his term "greenstone 

 porphyry " two distinct types of lava, one being the Post-Texan outburst of 

 dolerytic rock laden with magnetite, and the associated basic rocks passing near 



— — v 



*The latest maps of the United States War Department give the topography very well in 

 some details, and the compilation made for the Land Office map of Texas shows even the 

 Burnetan, Fernandan, Silurian, and Carboniferous uplifts as nearly as the actual topography 

 will admit. The imperfections in this last map are chiefly in the shape of extras which do 

 not occur in nature, and omissions which have been strangely made since the time of Marcy's 

 reconnoissance. 



f I have not seen much of the northern side of these mountains between Mount Scott and 

 the head of the East Fork of Cache Creek, but I very much doubt the existence of certain 

 ranges put down there upon recent maps, as they were not visible from any of the peaks 

 ascended by Professor Cummins or the writer. 



