1902.] HATCHER — OLIGOCENE AND MIOCENE DEPOSITS. 119 



The writer is well aware that the above correlation of the Gering 

 and Monroe Creek sandstones is open to criticism, as being at 

 present inadequately substantiated by direct paleontological evi- 

 dence. However, it should be remembered that on the other hand 

 there are no direct paleontological evidences against such correla- 

 tion, and that since sedimentation seems to have been continuous 

 at certain localities in this region, from the base of the White River 

 to the top of the Loup Fork, the John Day should be represented 

 somewhere in the series, and that the lithological sequence, as well 

 as the faunas of the overlying and underlying rocks, point to the 

 Gering and Monroe Creek sandstones as the logical representatives 

 of the John Day formation in this region. 



Origin of the Deposits. 



Until very recently the sediments of this entire series of deposits 

 have been very generally considered as of lacustrine origin, and the 

 boundaries of these supposed great Oligocene and Miocene lakes 

 have been set forth in text-books and scattered papers, and espe- 

 cially in the classroom lectures on the subject at our various uni- 

 versities, with a preciseness only surpassed by that of the modern 

 geographer when dealing with existing lakes. 



The earlier writers, including David Dale Owen, King, Hayden, 

 Leidy, Cope, Marsh and others, were always accustomed to speak 

 of these deposits as lacustrine, and they are at present so considered 

 l)y many authorities. Recently, however, their lacustrine origin 

 has been rejected, at least partially, by a considerable number of 

 competent observers, several of whom have had most excellent 

 opportunities for studying them. This is especially true of the 

 upper or Loup Fork series of deposits, which has now come very 

 generally to be considered as of combined lacustrine, fluviatile, 

 flood-plain and seolian origin, instead of as having been laid down 

 over the bottom of a great and continuous body of water, as was 

 formerly supposed. 



With regard to the origin of the underlying White River series, 

 however, it has been different ; and with a few exceptions these 

 deposits are still regarded as of lacustrine origin. Dr. W. D. 

 Matthew, in an article entitled ''Is the White River Tertiary an 

 ^olian Formation?" published in the American Naturalist, for 

 May, 1899, was the first to seriously question the lacustrine origin 

 of these deposits. In his " Fossil Mammals of the Tertiary of 



