98 ENVIRONMENT OF VERTEBRATE LIFE, ETC. 



mentioned is still unsettled. Fragments of vertebrates of Wichita or Clear 

 Fork age were collected by the author near Buffalo Gap, a few miles south 

 of Abilene, Texas,' and west of the region between Abilene and San Angelo 

 no beds were encountered that could be correlated with the Double Moun- 

 tain. Ten miles east of Big Springs, Texas, the red shales and sandstones 

 carry Triassic fossils. From Mitchell County to as far north as Briscoe 

 County in Texas the uppermost Permo-Carboniferous beds are of Double 

 Mountain age; beyond that to the north, the position of the uppermost red 

 beds is less certain. In the Panhandle of Texas the exposures of red beds 

 in the Canadian River are probably the equivalent of the Greer and Quarter- 

 master (Whitehorse) of Oklahoma; the latter, at least, Gould considers as 

 entirely above the Cimmaron of Kansas. There is a strong suggestion of a 

 longer continuation of red-beds conditions in this region or an excessive 

 supply of material. Around the southern end of the Staked Plains the 

 exposure of the red beds is interrupted by the overlying Tertiary and 

 Mesozoic deposits. Between Big Springs and Midland the narrow strip 

 of red beds is apparently all Triassac, but there has been no conclusive 

 evidence of their age, either stratigraphic or paleontologic, reported. From 

 Midland to the Pecos River the exposed material is all Tertiary, but at the 

 bridge across the Pecos, on the Fort Stockton road, 20 miles east of Grand 

 Falls, and in the bed of the river near Grand Falls, there are exposures 

 of red shale and sandstone very similar in lithologic character to certain 

 phases of the Double Mountain formation of north central Texas. From 

 Grand Falls to Pecos only red sands and disintegrated red shale are exposed, 

 but on the east side of the Pecos River red beds again appear. The author 

 has been unable to obtain any evidence for the Permo-Carboniferous age of 

 these red beds other than their red color and assumed stratigraphic position. 

 They were first called Permian by Marcou in 1852, and the designation seems 

 to have clung for lack of any definite evidence to the contrary. Cummins,^ 

 in 1891, said: 



"We found no fossils in the beds west of the Plains, but as we had traced the 

 formation on both the eastern and northern sides there was no doubt as to its 

 being the same when we found it upon the west. * * * The strata lie un- 

 conformably on the Carboniferous, dipping at a small angle to the southeast." 



The red beds are seen only in isolated patches from Pecos north nearly 

 to Roswell, as they crop out from below the Tertiary covering. The best 

 exposure is just east of Roswell. The following description of the section 

 is given by Fisher:^ 



' Carnegie Inst. Wash., Year Book, p. 374, 1916. 



2 Cummins, W. P., Notes on the Geology of the Country West of the Plains, Third Annual 



Report Geological Survey of Texas, p. 212, 1891. 



3 Fisher, C. A., Preliminary Report on the Geology and Underground Waters of the Roswell 



Artesian Area, New Mexico, Water Supply and Irrigation Paper No. 158, U. S. 

 Geological Survey, p. 6, 1906. 



