LATER TERTIARY (MIOCENE AND PLIOCENE). 831 



blown or washed by tributary streams were clothed in a varied and beautiful flora, resembling, 

 in a general way at least, the vegetation of the South Atlantic and Gulf States at the present 

 day. In the ancient forest and about the shores of the old lake, now known as Lake John Day, 

 a veritable menagerie of strange and in part gigantic beasts found a congenial home. 



From the White Bluffs of the Columbia southward to the region described in this report 

 there are no barriers, but the surface of the country rises gradually from the broad valley of 

 the Columbia to the basaltic plateau of northeastern Washington. From studies made along 

 the Columbia in 1892, I was led to the conclusion that Lake John Day extended far eastward 

 and covered nearly all of southeastern Washington, even to the base of the Blue Mountains. 

 This view is now known to have been in part erroneous. The sediments of Lake John Day are 

 but poorly exposed to the east of Pasco and Wallula, and their extent in that direction, although 

 not clearly shown, is certainly far short of the Blue Mountains and of the Idaho boundary. They 

 cover the Eureka Flats, however, as is shown by a well 198 feet deep at Eureka Junction, which 

 is all in strata similar to those exposed in the White Bluffs of the Columbia but does not reach 

 the bottom of the formation. Fossil leaves were found in the rock removed in digging the well, 

 similar to those obtained from other portions of the John Day system. With the exception of 

 the rocks found at Eureka Junction, no exposures of the Lake John Day system have been 

 recognized in the region treated in this report. The sediment of the old lake does not occur 

 above the Columbia lava in the vicinity of Walla Walla, Dayton, and Starbuck, and its eastern 

 shore must have been to the west of these localities. 



The lacustral deposits described in the preceding section as being interbedded with the 

 Columbia lava are of about the same age as the John Day system and were accumulated under 

 similar conditions. They should perhaps be included in the same system, but further study 

 is necessary before a conclusion in this connection can be reached. 



Knowlton made a report on plants collected by Russell from an outcrop near 

 EUensburg, later placed in the EUensburg formation by George Otis Smith. (See p. 

 826.) Regarding the correlation Knowlton^*** concluded: 



The leaves from near EUensburg, Wash., are preserved in a moderately soft white chalky 

 matrix, that is in general very similar to the well-known material from the auriferous gravels 

 of California and the John Day Valley in Oregon. * * * 



Of the ten species enumerated [for hst see the work cited], s6ven, among which are the species 

 most abundant in specimens and the most positive in identification, have been found in the 

 auriferous gravels of California. Seven of the species have also been reported from the John 

 Day Valley, Oregon, of which number three are common to the auriferous gravels. The new 

 species (Populus russelli) has great affinities with Upper Miocene species of Europe. 



From this examination it appears that there can be no doubt but that the plants from 

 EUensburg are similar in age to the auriferous gravels and the John Day Valley. The John Day 

 VaUey deposit has always been caUed Miocene. The auriferous gravels, on the other hand, 

 were regarded by Lesquereux and others as PUocene, but a recent examination of that flora 

 based on extensive collections from Independence Hill, Placer County, Cal., seems to indicate 

 that they also are probably upper Miocene in age. 



L 12. WESTEBN MONTANA. 



Calkins, in an unpublished manuscript, has the following to say in regard to 

 the Tertiary in the Philipsburg quadrangle, Montana, which applies equally well to 

 adjacent areas of these rocks: 



Rocks of Tertiary age apart from the intrusives occupy relatively smaU areas, chiefly in 

 the valleys. The evidence at hand indicates that aU these rocks are strongly unconform- 

 able. * * * They he on various older formations indiscriminately, are not metamorphosed 

 by the intrusions, and are much less deformed than the Cretaceous and older sediments. The 



