PENNSYLVANIC-PERMIC PERIOD 567 



consists of cross-bedded conglomerates, grits, gypsum beds, and red shales, 

 which "are mainly continental deposits." "As distance from the moun- 

 tain sonrce of these clastic materials increases, the beds are naturally finer 

 grained and grade into shales and marls, and correlation of widely sepa- 

 rated sections becomes difficult-." 193 This horizon is believed to be the 

 continuation of the Oklahomian series of the Kansas section. 



The Chugwater red beds of Wyoming, averaging 1,200 feet in depth, 

 appear to hold the horizon of the Cutler. The fossils are few and there 

 are no brachiopods. The forms represented are: Schizodus wheeleri, 

 Aviculopecten curticardinalis, Pleurophorus, Bdkewellia ?, and Natica 

 lelia. 19 * 



In southwestern Wyoming occurs the Thayer formation, with a thick- 

 ness of 2,400 feet. It probably is the equivalent of the Chugwater and 

 Cutler. The fauna of these beds is composed of pelecypods, some of 

 which are: Aviculopecten weberensis, A. curticardinalis, A. parvulus, Mya- 

 lina permiana, Myacites inconspicuous ?, Baleewellia ?, Schizodus ovatus, 

 Sedgwickia concava. "They indicate an extension into Wyoming of the 

 Permo-Carboniferous of the Wasatch range." 195 



Permic of the northern Appalachian sea. — In this area marine faunas 

 ceased in the upper part of the Conemaugh, and all subsequent deposits 

 are of continental origin. If these are brackish-water deposits, there is 

 as yet no evidence of the fact known to the writer. Above the Monon- 

 gahela rests the Dunkard series of western Pennsylvania, eastern Ohio, 

 and West Virginia. The plants of these beds are Lower Permic, on the 

 authority of D. White, equivalent to the Atunian and Cuseler of Europe. 

 The reference in 1880 of the Dunkard to the Permic, by Fontaine and 

 I. C. White, "has been doubted by most American geologists. Eecently, 

 however, additional plant evidence has been obtained to show that the beds 

 above the Washington coal, 175 feet above the Waynesburg coal [the base 

 of the Dunkard], are clearly Lower Eothliegende (cf. Cuseler) ; and it is 

 not impossible that the Eothliegende boundary may, on the acquisition of 

 further paleontological material, be shown to lie unquestionably below the 

 Waynesburg coal." 196 



From a parting of the Wa}mesburg coal near Cassville, West Virginia, 

 at the very base of the Dunkard, Lacoe obtained many insects. Others 

 have been found at Fairplay, Colorado. These have been studied by 

 Handlirsch, 197 who has determined 93 forms. All belong to the Blat- 



103 Cross : Journal of Geology, 1907, pp. 662-668. 



19 * Darton : Bull. Geological Society of America, vol. 19, 1908, p. 438. 



195 Girty in Veatch : Professional Paper no. 56, U. S. Geological Survey, 1907, p. 52. 



198 D. White : Proceedings of the U. S. National Museum, vol. 29, 1906, p. 665. 



197 Handlirsch : Possilen Insekten, 1906-1908, p. 1149. 



