68 THE PERMO-CARBONIFEROUS RED BEDS OF 



Butters * in 191 3 gave a very detailed accotint of the " Pernio- Carbonifer- 

 ous" of the eastern foot-hills of the Rocky Mountains in Colorado. After 

 detailing the conditions in the various sections from the north line of Colo- 

 rado south he says: 



' ' Overlying this [the Ingleside] is the Lykins formation, and at one horizon about 

 200 feet from the base, at Heygood and Box Elder Canyons, Bellerophon crassus and 

 Myalina subquadrata were found. The same species are found in the Fountain and 

 Ingleside below. On this evidence, together with the fact that there is no angular 

 unconformity, and no marked difference of lithological character, this basal portion 

 of the Lykins is assigned to the Pennsylvanian period. On the northern slope of Table 

 Mountain, Larimer County, 40 to 50 feet higher than the fossiliferous stratum, and 

 separated from it by a gypsiferous series, another fossiliferous stratum occurs. This 

 is probably more than 300 feet from the top of the Lykins formation and seems to 

 be in the same stratigraphic position as the fossiliferous beds near Stout, and also 

 those in the crinkled sandstone near Perry Park. At Stout, and also at Table Moun- 

 tain, the 'crinkly' structure is not present. From this horizon Dr. G. H. Girty has 

 identified the following fossils : 



From Table Mountain: From Stout: From Perry Park: 



Myalina wyomingensis , Myalina wyomingensis. Myalina wyomingensis. 



Myalina peratlenuata. Myalina perattenuata. Myalina peratlenuata. 



Alula squamulifera. Alula squamulifera. 



Murchisonia butter si. Alula gilberli (?). 



Pleurophorus sp. 



"This fauna has recently been discussed. Alula squamulifera and Murchisonia 

 butter si described as new, and Allerisma (Pleurophorella?) gilberti removed to the 

 new genus Alula, by Dr. Girty.*" 



"It will be seen that the faunas are essentially the same, and, while some of the 

 species are new, the number of known forms is such that Dr. G. H. Girty believes 

 a tentative correlation with the Rico formation of the San Juan region is justifiable. 

 The Hermosa is Pennsylvanian, while the Rico is considered, tentatively, Permian. 

 This leaves 100 to 400 feet of shales to represent the Permian or the remainder of 

 the Permian, the Triassic, and all the Jurassic up to the Morrison. These sediments 

 are usually a soft red shale or shaly sandstone, and the conditions of deposition were 

 apparently unfavorable to the preservation of fossil evidence." 



Later in the same article he says : 



"Correlations. — The correlation of the Fountain, Ingleside, Lyons, and Lykins 

 along the foothills from the line to Colorado Springs is a question of recognizing the 

 same formation under different names. * * * Thus the Fountain of Fenneman in 

 the Boulder quadrangle is equivalent to the lower part of the Fountain of Cross in 

 the Pike's Peak area. The Fountain, Ingleside, and Lyons together are equivalent 

 to the lower Wyoming of the Denver Basin area. The Lykins is equivalent to the 

 Chugwater of Darton and the upper Wyoming of Emmons. The upper portion of 

 the Fountain and the Ingleside together are equivalent to Darton's Casper forma- 

 tion. The Lyons is equivalent to the creamy sandstone of the Denver Basin area, 

 but Darton's Tensleep is not the equivalent of the Lyons and the Creamy sand- 

 stone. It is a lower horizon, and can be correlated only with the lower portion of 

 the Lyons, and also the Ingleside. An explanation of this requires a description of 



» Butters, Bull. 5, Colorado Geol. Survey, 1913, p. 65. 

 ''Girty, Anns. N. Y. Acad. Sci., vol. 22, pp. 1-8, 1912. 



