G. H. Girty — Upper Permian in Westeim Texas. 363 



Art. XXX Y. — The Upper Permian in Westeim Texas i"^ by 

 George H. Girty. 



DuRiNa the field season of 1901, as a member of a party 

 under the direction of Mr. E. T. Hill, I examined a very inter- 

 esting series of Carboniferons strata in western Texas. The 

 route traversed was in part the same, though in an opposite 

 direction, as that pursued by the expedition under Captain 

 Pope in 1855, of which G. G. Shumard was a member. Our 

 point of departure was El Paso, and we passed eastward, 

 approximately along the thirty-second parallel, as far as the 

 headwaters of Delaware Creek, in the Trans-Pecos region. 

 There, finding that the old trail down Delaware was impractica- 

 ble, we turned southward, meeting the railroad at Toya. 



The region of special interest was the Guadalupe Mountains, 

 where Shumard collected a number of species, subsequently 

 described by his brother, B. F. Shumard, which indicated the 

 existence at this point of a peculiar Carboniferous fauna, essen- 

 tially different from anything known elsewhere in North 

 America. Shumard gives the following section of the Guada- 

 lupe Mountains :t 



1. Upper or white limestone 1,000 feet. 



2. Dark-colored, thinly laminated and foliated 



limestone 50-100 



3. Yellow quartzose sandstone 1,200-1,500 



4. Black, thin-bedded limestone _. 500 



The geologic series is finely exposed, and the order of super- 

 position of the beds is obvious. The constituent formations 

 are of rather unusual thickness and uniformity of composition. 

 In fact, though we were able to make only barometric measure- 

 ments, and though only the upper limestone was exposed in a 

 continuous section, I believe that the thicknesses assigned by 

 Shumard are too small. We measured 1,700 to 1,800 feet of 

 the upper limestone, while the middle member, a yellow sand- 

 stone, must contain from 2,000 to 2,500 feet. Ot the black 

 limestone, which forms the lowest member of the section, 

 probably not more than 500 feet are exposed, but the base was 

 not seen. 



Fossils were obtained from all these formations, but it is 

 especially of those from the upper one that I desire to speak. 

 The rock is a white limestone, sometimes stained yellowish or 

 reddish in the lower portion, where it is also quite siliceous. 



* Published by permission of the Director of the U. S. Geological Survey, 

 t Acad. Sci. St. Louis, Trans., vol. 1, 1860, p. 280. 



