CORRELATION AND PALEOGEOGRAPHY 239 



A closer homotaxis could harclly he found than that existing between 

 the Lower Washakie and Upper Bridger. That the Upper Washakie simi- 

 larly was laid down synchronously with the ^Fiddle Uinta is demonstrated 

 by the common presence of a rich DoJichorhiniis fauna characterized by 

 these very peculiar long-skulled titanotheres. 



The above diagram shows the connecting system which has enabled us 

 step by step to correlate not only the Bridger, Washakie, and Uinta, but 

 all the formations of our wonderful American Eocene deposits except 

 those at the very base of the Eocene or summit of the Cretaceous, which 

 still await further analysis. 



Our knowledge of the fluviatile Uinta B, or DoUchorhinus-Eohasileus 

 zone fauna, first made known through the discoveries of Peterson in 1894, 

 has been greatly enriched by the more re(;ent explorations of Douglas for 

 the Carnegie Museum and of Eiggs for the Field Museum, so that this 

 life zone becomes one of the best known of the Eocky Mountain series. 

 The overlying Uinta C, first explored by Marsh in 1871, is characterized 

 by the presence of the large, well horned titanotheres (e. g., Protitan- 

 otherium superhum), and we may confidently anticipate that through 

 further exploration exact correlation will be established between this 

 Protitanotherium, and DipJacodon zone and some of the basal formations 

 of the White Eiver Oligocene of the great Badlands of South Dakota. 

 Thus the top of the Eocene will be neatly articulated with the base of 

 the Oligocene. 



Lower Eocene 



Working downward from the Middle Eocene of the Bridger and pur- 

 suing the same methods, Granger and Sinclair^^ have made an ex- 

 haustive geologic and faunistic examination of the Wind Eiver and of 

 the Wasatch, supplementing the geologic work of Dart on (1906),^^ 

 Yeatch (1907) and Fisher (1906).t The exact faunistic touch on the 

 upper levels with the base of the Bridger has not been secured, because 

 (see table, page 214) Bridger A is almost barren and the very summit of 

 the Wind Eiver is also barren ; the exposures of the "Wind Eiver Series'' 

 of the Beaver Divide, a barren part of which may correlate with the 

 "Bridger." 



" W. J. Sinclair and Walter Granger: Eocene and Oligocene of tlie Wind River and 

 Bighorn basins. Bulletin of the American Museum of Natural History, vol. xxx, art. vii, 

 July 11, 1911, pp. 83-117. 



"N. H. Darton : Geology of the Big Horn Mountains. I'. S. Geological Survey, Profes- 

 sional Paper No. 51, 1906. 



tFisher, Cassius A. : "Geology and Water Resources of the Bighorn Basin, Wyoming." 

 U. S. Geological Survey, Professional Paper 53, 1906, 



