Stanton and Yaughan — Section of the Cretaceous, etc. 21 



Art. V. — Section of the Cretaceous at El Paso, Texas /* 

 by T. W. Stanton and T. Wayland Yaughan. 



The detailed section of the Cretaceous of the Texas region 

 here described is of interest because it is the most western of 

 the outlying areas of the Texas Cretaceous as yet described, 

 being 600 miles south of west from Denison, and 530 miles 

 north of west from Austin.f 



Although the details of the El Paso section have not hitherto 

 been published, many references^: have been made to it in 

 the literature, and collections of fossils have been made there 

 by Mr. R. T. Hill and Dr. E. A. Mearns, U. S. A. Mr. 

 Hill's collection is at the Johns Hopkins University, and that 

 of Dr. Mearns is deposited in the IT. S. National Museum. 



The section§ here described was made in Mexico and New 

 Mexico near the Initial Monument of the Mexican Boundary 

 Survey, about three miles west of the city. The lowest part 

 of it is exposed in the cutting of the Southern Pacific railroad 

 on the west bank of the Rio Grande, where it cuts the pass 

 through the mountains. The section extends from here to the 

 top of the hill across the arroyo southeast of the Initial Monu- 

 ment of the Boundary Survey. The rocks are greatly faulted, 

 folded and disturbed by igneous intrusions, so to obtain the 

 sequence and thickness of the beds it was necessary to estab- 

 lish horizons and measure between them where we could find 

 them. Therefore, the highest beds of the section are not at 

 the southeastern end of the exposures that we examined, but 

 just north of a line joining the initial and second monuments 

 of the Boundary Survey, where the rocks abut against a mass 

 of hornblende porphyrite which is intruded through them. 

 The downthrows of the faults are usually to the west. 



The following is a description of the section beginning with 

 the highest bed : 



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



f Gabb in vol. ii of the Paleontology, Geol. Survey of California, pp. 257-276, 

 1869, describes a collection of fossils made by Remond from Sierra de las Conchas, 

 near Arevichi, Sonora, Mexico. He recognized their resemblance to the Cre- 

 taceous fossils of Texas. Mr. R. T. Hill says concerning these fossils, in this 

 Journal, vol. xlv, p. 313, April, 1893, ''The fossils are the characteristic fauna of 

 the latest or Washita division of the Comanche Series, and resemble the varia- 

 tions seen at El Paso and Juarez and throughout the northern littoral of the latest 

 beds of the Comanche Series." 



% R. T. Hill: Bull. Geol. Soc. of America, vol. ii, pp. 517 and 518, May, 1891; 

 this Journal, vol. xlv, p. 312, April, 1*93; Bull. Geol. Soc. America, vol. v, 

 p. 332, March, 1894; this Journal, vol. 1, p. 233, September, 1895. T. W. 

 Stanton: In notes on a collection of fossils from near Belvidere, Kansas, pub- 

 lished in R. T. Hill's " Outlying Areas of the Comanche Series in Kansas, Okla- 

 homa, and New Mexico," this Journal, vol. 1, p 218, Sept., 1895. 



§ The description of tho Denison Section published by R. T. Hill, Bull. Geol. 

 Soc. of America, vol. v, pp. 303-304, and plate 13. March, 1891, should be con- 

 sulted, while reading the description here presented. 



