THE PLAINS PROVINCE 111 



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

 conditions in the various sections from the north line of Colorado 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, Betterophon 

 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 char- 

 acter, 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 fos- 

 siliferous beds near Stout, and also those in the crinkled sandstone near Perry Park. 

 At Stout, and also at Table Mountain, the "crinkly" structure is not present.' 



" ' 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 Pikes Peak area. The Fountain, Ingleside, and Lyons together 

 are equivalent to the lower \Yyoming 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 formation. 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 sandstone. 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 the conditions in northern Colorado. This has 

 been made under " Formation names." Darton's Tensleep in Colorado is probably 

 in part equivalent to the sandstone-limestone series; that is, the Ingleside series. 



"'Owing to the absence of fossil evidence in the Badito formation, and from 

 the fact that it is separated so widely from any recognized Fountain exposures, 

 it has not been definitely correlated with the Fountain. Lithologically they are 

 very similar, and the Badito overlies pre-Cambrian rocks unconformably, bearing 

 about the same relation to the overlying formations as does the Fountain. On 

 these grounds they are at least approximately in the same horizon. 



"'The Cutler formation is defined as that portion of the "Red Beds" lying 

 above the Rico, where that is present, or otherwise as succeeding the Hermosa 

 and below the Dolores. The Cutler is assigned to the Permian purely on strati- 

 graphic grounds, and is separated from the Rico by a purely arbitrary line. 

 There seems to be as good ground for assigning the Lykins, above the crinkled 

 sandstone, or at least the lower portion of it, to the Permian, and thus correlating 

 it with the Cutler. 



' ' Above the Cutler formation in the San Juan region is a series of sandstones, 

 sandy shales, and conglomerates which vary in thickness from 800 to 400 feet, 

 and from that down to 30 feet at the San Miguel River, disappearing entirely 

 north of this river. These shales and sandstones are a bright vermilion in color, 

 and are known as the Dolores formation. They are assigned to the Triassic 

 age because of the scanty, but widespread, vertebrate, invertebrate, and plant 

 remains. The extreme upper part of the Lykins in Larimer County may be 

 equivalent to the Dolores and thus be Triassic. If so, it is impossible to draw a 

 line between the Permian and Triassic in eastern Colorado.'" 



