G. B. Richardson — Paleozoic Formations. 475 



fauna in the Guadalupe Mountains, near the Texas-New Mex- 

 ico boundary about 60 miles west of Pecos River. R. S. Tan- 

 disagreed with this conclusion,* but G. H. Girty in 1901 con- 

 firmed the early work,f and he has described the unique fauna 

 in an elaborate report which is now in press.:}: And in L904, 

 J. A. Udden reported the presence of Carboniferous rocks in 

 the Chinati Mountains in Presidio County. § 



The present writer in 1903 made a reconnaissance of that 

 portion of trans-Pecos Texas in which the greater part of the 

 Paleozoic rocks are exposed,! and later, in connection with 

 the survey of the El Paso and Van Horn quadrangles, had an 

 opportunity to map the formations in detail and to collect 

 fossils. These have been examined by Messrs. C. D. Walcott, 

 E. O. Ulrich and G. H. Girty, and the writer is particularly 

 indebted to Dr. Girty, who accompanied him in the field both 

 in the El Paso and Van Horn regions. 



The formations which are the subject of this paper outcrop 

 in the Franklin and Hueco Mountains in the El Paso quad- 

 rangle, and in the Sierra Diablo, Delaware Mountains and 

 associated groups of hills in the Van Horn quadrangle. These 

 two quadrangles, which have recently been mapped by the 

 U. S. Geological Survey, are situated about 60 miles apart and 

 they include practically all of the known occurrences of lower 

 Paleozoic rocks in trans-Pecos Texas. The following table 

 summarizes the Paleozoic formations in the El Paso and Van 

 Horn quadrangles : 



Cambrian. 



Bliss Sandstone. 



The main occurrence of the Bliss sandstone is along the 

 eastern slopes of the Franklin Mountains, but the considerable 

 faulting to which the range has been subjected causes its dis- 

 tribution to be very irregular. The Bliss is a massive, fine- 

 textured, brownish sandstone that varies from a few -feet to 

 slightly more than 300 feet in thickness. The lower beds are 

 indurated and are practically quartzites and at the base of the 

 formation the strata are coarser textured, locally are conglom- 

 eritic and contain pebbles of the underlying rocks. The 

 sandstone is composed of small grains of quartz imbedded in a 

 matrix of sericite and kaolin. In places the Bliss sandstone 



* Reconnaissance of the Guadalupe Mountains, Bull. No. 8, Geol. Survey 

 of Texas, 1892 



f This Journal (4), xiv, p. 863. 



X The Guadalupian fauna, U. S. Geol. Sur., Prof. Paper No. 58. 



§The Geology of the Shafter Silver Mine District, Bull. No. 8, Univer- 

 sity of Texas Mineral Survey, 1904. 



I Report of a reconnaissance in trans-Pecos Texas north of the Texas and 

 Pacific Railway, Bull. No. 9, University of Texas Mineral Survey, 1904. 



