50 Vaughan — Outlying Areas of the Comanche Series. 



in G. county, directed me to the following locality : about ten 

 miles south of west of Arapaho, Sec. 11, T. 12 K, R. 18 W., 

 on the north side of the Washita River, west of Barnitz Creek. 

 Here there are outcrops of a shell limestone, composed of 

 Gryphcea pitcheri Marcou (G. forniculata White), imbedded in 

 a matrix of yellow clay, which is often washed out, leaving 

 only shells stuck together. The bed is scarcely two feet thick 

 and forms the tops of small knolls. These patches of the 

 Cretaceous do not occur on the very top of the divide, but on 

 the flanks of the Red Beds hills which rise considerably higher. 



Judging from Marcou's map and description, I believe that 

 the above is his original Comet Creek locality. Mr. Dulany 

 informed me that the western bluffs of Panther Creek, south- 

 east J, Sec. 12, T. 13 K, R. 20 W., 18 miles west and three 

 miles north of Arapaho, are composed of the Gryphcea rock. 

 The rock occurs all along the creek from its mouth to its head. 



No outcrops of the Cretaceous were found south of Arapaho. 



The studies that have been presented in the preceding, show 

 (1) that the Cheyenne sandstone becomes thinner and disap- 

 pears to the south of Avilla; (2) that the Kiowa shales rest 

 directly upon the Red Beds south of Avilla ; (3) that these 

 shales become thinner to the south and are represented in the 

 vicinity of Taloga and Arapaho only by the bed of Gryphcea 

 forniculata a few feet thick, now left as patches in a few 

 places ; (4) that south of Camp Supply the lower Cretaceous 

 oeds do not occupy the tops of the highest divides, but have 

 been deposited on the flanks of the Red Beds hills, thus show- 

 ing that the country in the vicinity of Arapaho and Taloga was 

 not completely submerged in Lower Cretaceous time. The 

 Wichita Mountain region was, as has previously been shown,* a 

 promontory projecting westward into the Lower Cretaceous 

 sea which sent an arm northward around its western end. The 

 existence of the Wichita promontory may explain the dif- 

 ference between the " Outlying Areas " of the Comanche Series 

 and the main areas in Central Texas. (5) Marcou's Gryphcea 

 tucumcarii, asserted by him to be Jurassic, was found in the 

 same matrix with his " JNeocomian " G. pitcheri (non-Morton) 

 or even in higher beds, thus adding more strength to the chain 

 of evidence by which his " Jurassic " has been proven not only 

 not Jurassic, but that it belongs to Cretaceous beds above his 

 so-called Neocomian, which is far above the base of the Ameri- 

 can Cretaceous. 



Washington, D. C. 



♦Hill, this Journal, vol. 1, p. 229, September, 1895. 



