146 ENVIRONMENT OF VERTEBRATE LIFE, ETC. 



Texas, which are, at least, no higher than the Double Mountain, and these, 

 with the Castile gypsum and Rustler limestone, lie upon an erosion surface 

 which truncated the Delaware limestone and (in all probability) the Capitan 

 limestone, but they are below the Greer and Quartermaster (Whitehorse) 

 of western Oklahoma. Beede says of the Guadalupian and overlying beds:^ 



"The stratigraphic relationships of these Permian beds are peculiar and 

 interesting. They are brought to the surface by a westward-facing fault-scarp 

 as it dies out into a fold to the south. Other mountains occur to the west and 

 northwest with older faunas, and only in this one locality is the nearly full section 

 of the Guadalupian rocks shown. The Capitan limestone (white Permian lime- 

 stone of Shumard) is 1,700 or 1,800 feet in thickness. Below this is the Delaware 

 Mountain formation, composed of dark limestones and sandstones with a black 

 limestone 200+ feet thick beneath it, giving, all told, some 2,500 feet to this 

 formation and a total of about 4,000 feet to the whole Guadalupian section as 

 shown at the southern extremity of the mountains. The stratigraphy was largely 

 worked out by Richardson. To the east, on the dipslope of the mountain, the 

 Capitan limestone is wanting. An erosional unconformity is found on the Dela- 

 ware Mountain formation upon which rests the Castile gypsum. The exposures 

 of the region show 50 or 60 feet of it and a well at Rustler Spring penetrated it to 

 a depth of 300 feet. To the east, and upon this, lie the Red Beds." 



Richardson says:^ 



"The Castile gypsum along its western outcrop lies in little knolls and valleys 

 of the underlying Delaware Mountain formation, indicating an erosional un- 

 conformity. Another evidence of unconformity at the base of the gypsum con- 

 sists in the absence of the Capitan limestone. It appears that either the gypsum 

 was deposited at or near the top of the Delaware Mountain formation as a lens 

 which did not extend westward to intervene between the Delaware Mountain 

 formation and the Capitan limestone in the Guadalupe Mountains, or that 

 erosion removed the former southwestward extension of the limestone (the thick- 

 ness of which is unknown) before the deposition of the gypsum. The former 

 supposition necessitates the correlation of the Rustler formation, which overlies 

 the gypsum, with the upper part of the Delaware Mountain formation or with 

 the Capitan limestone. But there is little to support this interpretation, and it 

 is tentatively assumed that the Castile gypsum and the Rustler formation were 

 formed after the deposition and erosion of a part of the Capitan limestone." 



C. PERMO-CARBONIFEROUS OF ARIZONA. 



The red Abo sandstone of New Mexico carries vertebrate fossils very 

 similar to those from El Cobre Canyon and Arroya da Agua, and this sand- 

 stone is revealed to the west in the Jemez uplift and so carried west to the 

 region of Fort Defiance, Arizona, whence it can be traced south to Fort 

 Wingate in New Mexico and the Grand Canyon region. The sandstone in 



^ Beede, J. W., Review of the Guadalupian Fauna by Geo. H. Girty, Jour. Geol., vol. xvii, 



p. 672, 1909. 

 ^ Richardson, G. B., A Reconnaissance in Trans-Pecos, Texas, University of Texas Mineral 



Survey Bull. No. 9, p. 43, 1904. 



