1919] Merriam: Tertiary Mammalian Faunas of Mohave Desert 441 



and those at Ricardo as distinct divisions, since the evidence of the 

 faunas indicates that the deposits were laid down in rather widely 

 separated epochs. The known fauna of the Barstow syncline occurs 

 near the top of the section, and it is very doubtful whether beds 

 containing a fauna like that of the much more advanced stage of 

 Ricardo is present in the Barstow section. The fauna at Ricardo 

 occurs through the greater part of the Red Rock Canon section. 

 Though it is possible that the lower Ricardo beds contain a faunal 

 assemblage similar to that of the Barstow region, evidence indicating 

 the presence of a typical Barstow fauna has not been obtained. The 

 Rosamond series of Hershey may include beds containing the older 

 fauna of Barstow, but it is doubtful whether it comprises sediments 

 of the stage represented at Ricardo. 



In an earlier publication the writer 8 referred to the fauna of the 

 Barstow syncline as the Mohave fauna, this name being considered 

 mainly as a geographic designation. Later, in order to avoid con- 

 fusion with other Tertiary faunas occurring in the Mohave area, the 

 name Barstow 7 has been used for this faunal assemblage, and Barstow 

 formation 8 for the beds containing the Upper Miocene or Barstow 

 fauna. This formation comprises the uppermost of five divisions in 

 the Barstow syncline, described by Baker 9 as the Fossiliferous Tuff 

 member, and any other beds which may be recognized as representing 

 the horizontal or vertical extension of the same depositional unit. 

 The limits of the Barstow formation may be found to correspond with 

 those of the Fossiliferous Tuff member, or they may include a greater 

 range of sediments above and below. It is possible that the Barstow 

 fauna occurs in all of the strata of the Barstow syncline. It is also 

 easily possible that the lowest strata of that section will be discovered 

 to contain a faunal assemblage much older than the particular Upper 

 Miocene assemblage known in the Fossiiiferous Tuff. The Resistant 

 Breccia Member immediately below the Fossiliferous Tuff in Baker's 

 Barstow syncline section seems to contain a representation of the 

 Barstow fauna, and may ultimately be included in the Barstow 

 formation. Should the Resistant Breccia be recognized as a distinct 

 formation the name Barstow group may be used for the sequence of 

 formations. 



e Merriam, J. C, Univ. Calif. Publ., Bull. Dept. Geol., vol. ,6, p. 168, 1911. 

 7 Merriam, J. C, Univ. Calif. Publ., Bull. Dept. Geol., vol. 8, p. 285, 1915; 

 vol. 9, pp. 7, 49, 1915; vol. 9, p. 171, 1916. 



s Merriam, J. C, Pop. Sci. Mon., p. 252, March, 1915. 

 »Op. cit., vol. 6, pp. 345-346, 1911. 



