Page:The Journal of geology (IA journalofgeology21894univers).pdf/55

Tertiary period, that is, that they have been forming since the beginning of that epoch.^[1]...The evidence of the geological age of the gravel deposits afforded by the plants found in the sedimentary beds underlying the latest eruptive masses in the mining region of the Sierra has already been discussed by Mr. Lesquereux. He distinctly recognizes the presence in this flora of forms identical with or closely allied to those of the Miocene; but still calls the age of the group Pliocene. Something of the same kind seems to be legitimately inferred from the animal forms of the same deposits. There are certain fossils which have been found only in deep-lying gravels like those of Douglas Flat and Chili Gulch. No traces of the rhinoceros, the elotherium or the small equine animal referred with doubt by Leidy to Merychippus have ever been found in deposits which could by any possibility be proved to be more recent than the basaltic overflow. It is true that the evidence thus far collected is but fragmentary. Still, taking it for what it is worth, it may be said that the affinities of these animals found in these lower deposits would indicate a Miocene rather than a Pliocene age. There are also, it is believed, stratigraphical reasons for admitting that some at least of the deposits containing these older fossils may be proved by other than palæontological evidence to belong to an older series than those strata which, though anterior to the basalts, yet contain a fauna decidedly mere Pliocene than Miocene in character."

A collection of plants made from the older auriferous gravels upon the northern end of the Sierra Nevada was examined by Professor Lesquereux, who reported that their relation is evidently to the Miocene (U. S. Geological Survey, Eighth Annual Report, p. 419). Professor L. F. Ward, who examined the same collection, agreed that they were Miocene, most likely upper Miocene.

Recently the evidence afforded by the plant remains has been