476 INDEX TO THE STRATIGRAPHY OF NORTH AMERICA. 



into a number of formations of comparatively limited extent similar to the Castile gypsum 

 and the Rustler formation, which when traced for a number of rmles beyond the area in which 

 they were named lose their individual character and become difficult to recognize as such. The 

 formations of the red-bed group are characteristically lenticular. * * * ^ 



The red beds of Pecos Valley are delimited above, as Cummins and Drake determined a 

 number of years ago, by an erosional unconformity, which separates them from the overlying 

 Dockum formation, of Triassic age. The lower limit of the red beds of Pecos VaUey, defined 

 as the lowest occurrence of either red strata or of gypsum, is variable and is not a definite hori- 

 zon but rather forms a zigzag line extending diagonally across the strike of the rocks. * * * 

 [In central New Mexico] almost the entire Carboniferous section is composed of red beds. 



Fossils are of rare occurrence in these red rocks, although at a few localities shells have 

 been obtained from the interbedded limestones, and fragments of fossil wood also have 

 been found. Dr. Girty does not feel justified in saying anything definite as to the age of the 

 fossils collected from the red beds either by Mr. Fisher or by myself. These include Schizodus 

 ovatus and Pleurophorus aff. subcostatus from 7 miles northwest of Roswell, N. Mex., and a 

 Schizodus having the general shape of S. Jiarei, and a form suggesting by its shape a sniaH 

 Myalina from the Rustler HjUs, El Paso County, Tex. Nevertheless the stratigraphy indicates 

 that the red beds of the Pecos Valley are to be correlated with part of the Permian red beds 

 of Oklahoma and northwest Texas, for they were connected by tracing around the northern 

 border of the Staked Plains, by W. F. Cummins in 1891. * * * Cummins's work has been 

 confirmed by C. N. Gould, who has mapped the Greer and Quartermaster formations, which are 

 part of the Permian red beds of Texas and Oklahoma, across several counties in the panhandle 

 of Texas, and along the Canadian River as far as the Texas-New Mexico boundary. 



This stratigraphic correlation is in agreement with paleontologic data recently obtained 

 by Dr. J. W. Beede, * * * ^j^q found fossils in a limestone in the red beds south of Lake- 

 wood, N. Mex., which he correlates with the Whitehorse-Quartermaster fauna. 



The Permian of northern Texas is continuous with that of Oklahoma in area 

 and stratigraphy. It comprises red beds, which grade southward into blue clays 

 and limestones, just as the red beds of Oklahoma change northeastward into similar 

 rocks. Cummins ^^^ says: 



In previous discussions of the Permian formation in Texas " I have separated the strata 

 into three divisions, naming them Wichita, Clear Folk, and Double Mountain, the Wichita 

 being the lowest in the series. In my description of the Coal Measures in Texas I separated 

 the strata into five divisions, giving to the upper division the name of Albany and the one 

 immediately below that the name of Cisco. * * * 



The Wichita division was described as extending southward as far as the Salt Fork of the 

 Brazos River. It is represented as resting on the top of the Cisco division of the Coal Measures, 

 along its entire eastern border, and as being overlain by the Clear Fork division along its entire 

 western border. 



The Albany division of the Coal Measures was described as beginning on the north at the 

 Salt Fork of the Brazos River and extending southward to the southern limits of the Coal Meas- 

 ures in the State, resting directly upon the Cisco division and overlain on the west by the Clear 

 Fork division of the Permian. It will therefore be seen that the Wichita and Albany divisions 

 were made to occupy the same stratigraphic position. 



At the time these divisions were first described the relationship between them could not be 

 determined from the facts then in my possession. The area of the Wichita division was known 

 to be Permian and had been somewhat described prior to my giving it the present designation. 

 It was embraced in the area known as the "Red Beds" of Texas. In it the invertebrate fossils 

 were partly those known to occur in the Upper Coal Measures, and partly those that were char- 



a See Ann. Repts. Geol. Survey Texas, 1889 to 1892. 



