COMPOUND REGRESSIVE AND TRANSGRESSIVE OVERLAP 621 



At Two Buttes uplift, in southern Colorado, the shales beneath the 

 Dakota furnish further 

 Gryphcea corrugata Say. Pachy discus brazoensis (Shumard). 



and others. The beds appear to rest directly on the eroded surface of the 

 Red beds. 



On the Cimarron, in western Oklahoma, the fossiliferous Comanche 

 beds beneath the Dakota are dark shales, with layers of brown flaggy 

 sandstone and bands of somewhat calcareous sandstone 50 to 60 feet 

 thick. They contain 



Gryphwa corrugata Say. Protocardia multilineata Shumard. 



Ostrwa subovata Shumard. Pholadomya sancti-sabw Roemer. 



0. quadriplicata Shumard. Anchura Mowana Cragin? 



Plicatula incongrua Conrad. Turritella seriatim- granulat a Roemer. 



Inoceramus comancheanus Cragin. Hamites fremonti Marcou? 



Gervilliensis invaginata White. Pachy discus brazoensis (Shumard). 

 Trigonia emoryi Conrad. 



Below these beds, and resting with apparent disconformity on the 

 Morrison, are coarse cross-bedded sandstones with irregular bands of 

 pebbles, varying from 4 to 15 feet in thickness. 



This horizon with Gryphsea corrugata was traced westward to about 

 30 miles east of Folsom, New Mexico. At Tucumcari 60 feet of fossil- 

 iferous shales and sandstones underlie the Dakota, and at Canyon City, 

 Colorado, 85 feet of these shales and thin bedded sandstones underlie the 

 Dakota, and are separated from the Morrison by 35 feet of massive gray 

 sandstone with bands of fine conglomerate near the top. 



These beds are correlated with the Kiowa* and Mentor beds of Kansas 

 (Stanton). Regarding the age of these beds, Cragin* considered that 

 they "represent a group of sediments intermediate between the Fredericks- 

 burg and Washita division, and one which, as a meeting ground of the 

 faunas of these two divisions, can not satisfactorily be referred to either.""! 

 Hill,! on the otner hand, holds that the beds "represent the modified, 

 attenuated northern portion of the Washita division, and probably a 

 portion of the Fredericksburg division of the Comanche series of Texas." 

 Though there is a difference here as to the classification of the "Kiowa 

 division," as Cragin proposed to call it, there is unanimity in regarding 

 it as representing the border line of the Fredericksburg and Washita. 



At Marquette, McPherson county, Kansas, the following sections oc- 

 curs :§ 



* American Geologist, vol. xvi, pp. 357-386. 



t Ibid. : Loc. cit., p. 383 



i Am. Jour. Sci., 3d ser., vol. 49, pp. 205-235. 



§ C. N. Gould : American Geologist, vol. 25, pp. 35, 36. 



