204 A. J, TIEJE 



with the Lyons; (2) fine and uniform grain; (3) vertical alternation 

 of shale and sandstone and lateral passage of the one into the other ; 

 (4) presence amid the general red material of green splotches and 

 lenses; (5) occurrence of mud lumps and ripple marks; (6) very- 

 fine cross-bedding; (7) origin of the "crinkled" bed, which is not 

 always sandstone, but may carry some thin beds of limsetone, and 

 which may involve varicolored shale lenses, or may even be lime- 

 stone. Not disclosed in the section is the important fact that the 

 upper few hundred feet of the Lykins often contain gypsum beds, 

 a notable one being 90 feet thick at Red Creek, southwest of Colo- 

 rado Springs. These gypsum beds all seem to lie above a horizon 

 equivalent to that of certain limestones near the Wyoming line, 

 which carry marine Permo-Carboniferous fossils. 



Description: variants of the formation. — South and north of the 

 Cache la Poudre to Colorado Springs strip, conditions are as follows. 

 If the sandstones and shales lying above the Fountain sediments 

 west of Pueblo and Walsenburg (see p. 200) are not of Lyons 

 time, they are probably of Lykins time, since they are unconfor- 

 mable beneath Morrison beds. In the Purgatoire Valley, the 

 Lykins, in all probability, is represented by 800 feet of red sand- 

 stones and shales, with gypsum. Any still further eastward exten- 

 sion of the Lykins is discussed under its paleogeography. As to 

 northern Colorado, Butters and the writer (still in accordance with 

 Henderson) are again at variance. Butters believes that the Lykins 

 formation lies directly upon his "Ingleside," and that the writer's 

 "Lyons" is a southern expansion of a thin cross-bedded sandstone 

 which first appears near the Cache la Poudre River and rapidly 

 thickens southward.^ The writer thinks that Butters' lowest 

 Lykins bed (a shale) merges laterally southward into lower Lyons 

 sands, and that the cross-bedded sandstone, so emphasized by 

 Butters, merges into somewhat higher Lyons sands. The variance 

 hardly bears upon the problems here under discussion, because the 

 northern beds are still maruie or semimarine. 



Interpretation: marine hypothesis. — Those who regard the Foun- 

 tain and Lyons sediments as marme assume, without any argument, 

 that in Lykins time the eastern sea deepened. 



' R. M. Butters, op. cit., p. 76. 



