362 F. B. Loomis — Origin of the Wasatch Deposits. 



plete drying postulated for the red beds. The top of Tat man 

 Mountain is flat and on a level with several adjoining buttes 

 north of the Grey Bull River. It probably marks about the 

 end of these deposits. 



To the north and in the center of the basin, the Wasatch 

 beds are very nearly horizontal, but approaching the Owl 

 Creek Mountains there is a constantly increasing dip rising to 

 23 degrees immediately adjoining these mountains, so that 

 they would seem to have become greatly elevated since the 

 Wasatch was laid clown. 



As to correlation, the Tatman Mountain fossil levels are the 

 typical and classical locality for Wasatch fossils, and these 

 have furnished the standard. I find little difference between 

 the two levels. The Buffalo Basin level, however, is a distinct 

 horizon, and while the fossils are scarce they show a material 

 approach to the typical Wind River series. There is (1) a 

 noticeable paucity of horses, especially of the species most 

 abundant in the Wasatch, Eohippus cristatus alone being 

 represented ; (2) Systemodon is entirely lacking, as in the 

 Wind River; (3) Heptodon, a good Wind River genus, is 

 present, and Phenacodus is unexpectedly abundant; (1) Lamb- 

 dotherium, another Wind River type, is common, while 

 Coryphodon is rare. The two species of rodents found were 

 typical of that locality. Paramys was not obtained in the 

 lower level on Tatman Mountain, but increases in abundance 

 as one goes upward. This Buffalo Basin fossil level is, I 

 believe, very close to, or represents the base of the Wind 

 River, which would make the uppermost 1000 feet of the 

 Wasatch beds belong to the same period as the Wind River in 

 the basin south of Owl Creek Mountains. My former opinion 

 is thus reversed, yet taking the presence of Lambdotherium, 

 Heptodon and Paramys into consideration, together with the 

 lack of Systemodon and the typical species of Eohippus, it 

 seems a necessary conclusion. A comparison of the above 

 summary with that of Wortman" in 1891 shows little agree- 

 ment between them, his list being typically that of Wasatch 

 species. However, from the description of the camp in Buf- 

 falo Basin, f I am convinced that his locality represents a lower 

 level than that explored by the Amherst expedition, since it 

 lies much further to the southeast. The Amherst party 

 worked from a spring in the western border of the basin, at 

 the very head of Fifteen Mile Creek ; Wortman's list is simi- 

 lar to that of the upper level on Tatman Mountain. 



In summarizing the foregoing statements, it is seen by an 

 analysis of the fauna that the Wasatch beds seem to be the 

 result of flood-plain deposits ; a study of the lithological nature 



*Bull. Amer. Mus. Nat. Hist., vol. iv, p. 83. fLoc. cit., p. 146. 



