422 GEOLOGY OF NORTHWESTERN TEXAS. 



" (a) The formation is lithologically quite distinct from the subjacent 

 Carboniferous strata. 



" (b) The pevailing color of the formation is a dark red, brown, and some- 

 times a brighter red, like the Triassic generally is in Europe and America. 



" (c) The lithified layers alternate with beds of clay and clay shale, as do 

 the stony layers in the Triassic of the Atlantic slope and in much of the Jura- 

 Trias of the west. 



"(d) A massive layer of gypsum and numerous seams of selenite and 

 satin spar appear in the formation, in which respects it corresponds with de- 

 posits further southwest, which have been referred to the Jurassic or Triassic 

 on both petrographic and paleontologic grounds. 



"(e) There are frequent shore marks, ripple marks, and rain drops, in 

 which the formation simulates the Triassic of the Atlantic slope and many 

 other regions. 



"(f) There is a marked absence of fossils, a characteristic of the Triassic 

 generally. 



"(g) The formation is continuous to Red River, and appears to be strati- 

 graphically connected with similar rocks beyond, which have already been 

 referred to the Jurassic or Triassic on various grounds. 



" (h) The surface of the formation was deeply eroded before the deposits 

 of the Dakota or other Cretaceous formations were laid down. 



"In brief, the lithological characters, in so far as they may be regarded as 

 criteria in the correlations of formations, and the stratigraphy alike, suggest 

 that the red rocks of Southern Kansas represent the group of strata elsewhere 

 found between the base of the Cretaceous and the summit of the Carbonifer- 

 ous; and although the evidence is not sufficient finally to demonstrate the age 

 of the rocks, it is sufficient to warrant the provisional application to them of 

 the name Triassic." 



The following comments may be made upon this summary in its applica- 

 tion to the Texas strata: 



(a) It is certainly different from the underlying Carboniferous, as has 

 been shown elsewhere in the Report. 



(b) The mere color of a rock would not distinguish between the Triassic 

 and the Permian. 



(c) The lithified layers alternate with beds of clay and clay shale in the 

 lower Red Beds of the Permian in Texas, and would go as far to prove these 

 upper beds Permian as would conclusions drawn from Triassic rocks in 

 another part of the United States prove these Triassic. 



(d) The occurrence of massive gypsum and seams of selenite does not prove 

 anything, for the reason that they may occur in any of the strata since the 



