RELATIONSHIPS OP RED BEDS 199 



la})ping Tertiary. This boundary is broken, however, by an arm-like 

 extension of the Red beds which reaches along the Canadian river into 

 New Mexico. In Kansas for a short distance the limit of the Permian 

 is the contact with the overlapping Lower Cretaceous. Thence north- 

 ward it is overlapped by the Tertiary and farther on by the Upper Cre- 

 taceous. Within the area of the Red beds are the Wichita mountains, 

 consisting of igneous and old Paleozoics, which were formerly wholly 

 covered by the red sediments which in this locality were largely of local 

 origin. 



The lowest rocks of the Coal Measures are found in western Arkansas 

 and eastern Indian territory. In this area they have a folded structure. 

 In the remaining portion of the field the rocks have low dips to the west- 

 ward, with the exception of the area immediately south of the Arbuckle 

 mountains and east of the limit of the red color. There the rocks are 

 closely folded. The date of the folding in Arkansas and eastern Indian 

 territory is pre-Cretaceous. It may be pre-Permian ; but as to this there 

 is at present no definite evidence. In the small area south of the Ar- 

 buckle mountains the folding occurred before the deposition of the red 

 sediments, which lie unconformably on the Coal Measure rocks, and it 

 appears now that it was pre-Permian. 



LiTHOLOGic Divisions of the Permian and Carboniferous 



Considering the character of the sediments of the Carboniferous and 

 Permian in the area here mapped, it is seen that in Arkansas and cen- 

 tral Indian territory the sediments consist of sandstones and shales, in 

 which there are coal beds. Going westward the area of the shales and 

 sandstones broadens and extends northward into Kansas and southward 

 into Texas. Lying to the north and south of this central region there 

 are, in Kansas and Texas, as equivalents of the sandstones and shales of 

 the middle portion of the section, lithologic divisions in which limestones 

 are interbedded with the shales and sandstones. These northern and 

 southern divisions bear considerable resemblance to each other. The 

 frequent alternation of shale and sandstone beds with limestones indicates 

 that the conditions of sedimentation in the two areas were quite similar. 

 Their respective faunas have not been studied carefully, but they suggest 

 that the divisions may be correlated tentatively. 



It is not proposed to discuss here the source of the Carboniferous and 

 Permian sediments. Two striking features of the map which should be 

 noted, however, are the embayment of the red color to the eastward, the 

 limit being diagonal to the strike of the formations throughout a con- 



XXVIII— Bull. Geol. Soc. Am., Vol. 14, 1902 



