LOCATION, CHARACTER, AND FAUNA OF THE SECTIONS 261 



These fossils show no closer relationship with the Mentor and other 

 upper Comanche faunas than is indicated by the presence of some genera 

 in common. The specific identities all connect it with the upper Dakota 

 fauna of Nebraska. 



The Cretaceous section of central Kansas, as summarized in number 3 

 of the chart, includes the chalky limestone of the Niobrara, a shale repre- 

 senting the Carlile, limestones of the Inoceramus labiatus zone represent- 

 ing the Greenhorn, a shale less than 100 feet thick representing the 

 Graneros, the plant-bearing, largely continental sandstones of the Dakota 

 with a marine bed in the extreme upper part, and about 100 feet of sand- 

 stones and shales which are largely marine, though they include some 

 shore and lagoon deposits with plants of Dakota aspect. The fauna of 

 this basal, or Mentor, part of the Cretaceous section includes enough 

 characteristic Comanche species that also occur in the Kiowa shale of 

 southern Kansas and in the Denison formation of northern Texas to 

 justify its correlation with the upper part of the Washita group, though 

 the absence of Gryphcea corrugata, G. navia, and many others of the most 

 abundant and characteristic species of the Kiowa and of the Denison is 

 noteworthy. The Mentor fauna does not recur above the basal 100 feet 

 of the section. 



In the southern Kansas section, represented by number 2 of the chart, 

 the upper part of the Dakota and all of the later Cretaceous formations 

 have been removed by erosion; there is a greater thickness of marine beds, 

 with a well developed and distinctive Comanche fauna, represented in the 

 Kiowa shale and the overlying variable shales and sandstones which seem 

 to form a transition to the Dakota ; and at the base is the Cheyenne sand- 

 stone, about 50 feet thick, which Twenhofel has interpreted as of terres- 

 trial origin, deposited on relatively flat lands near the sea. The flora of 

 the Cheyenne sandstone resembles the Dakota flora, but may be specific- 

 ally distinct. The Kiowa fauna is characterized by the abundance of 

 Gryphcea corrugata, 67. navia, and many other Washita forms, together 

 with a few species, such as Exogyra texana and Schloenhachia acutocari- 

 nata, which in Texas are either restricted to or more abundant in the 

 underlying Fredericksburg group. 



TEXAS SECTION 



In northern Texas, near Denison, the section represented by number 1 

 of the chart shows a much greater thickening of marine sediments in the 

 Washita group, beneath which are thin representatives of the Fredericks- 

 burg and Trinity groups of the Comanche series. Beginning at the bot- 

 tom of the Washita, the succession is Kiamichi clay, Duck Creek forma- 



