V*-. 



HUMAN EEMAINS: DISCUSSION" OF THE EVIDENCE. 



283 



It appears probable on stratigraphieal grounds, as will be set forth in a 

 future chapter, that the detrital beds overlying the "bed-rock" of the 

 Sierra Nevada represent the whole Tertiary period ; that is, that they have 

 been forming since the beginning of that epoch. It also seems likely that 

 there has been no break in the series of events ; none, at least, of sufficient 

 magnitude to justify the drawing of a sharp line anywhere, so as to say, 

 above this is Pliocene, and below it is Miocene, or Eocene. 



The evidence as to the geological age of the gravel deposits afforded by 

 the plants found in the sedimentary beds underlying the latest eruptive masses 

 m the mining region of the Sierra lias already been discussed by Mr. Les- 

 quereux. He distinctly recognizes the presence in this flora of forms iden- 

 tical with, or closely allied to, those of the Miocene ; but still calls the age of 

 group Pliocene. Something of the same kind seems to be legitimately in- 

 ferred from the animal remains of the same deposits. There are certain 

 fossils which have been found only in deep-lying gravels, like those of Doug- 

 lass Flat and Chili Gulch. No traces of the rhinoceros, the elotherium, or 

 the small equine animal referred, with doubt, by Leidy to Mcn/cMppus, 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 the animals found in these lower deposits would 

 indicate a Miocene rather than a Pliocene age. There are also, it is believed, 

 stratigraphieal reasons for admitting that some, at least, of the deposits con- 

 taining these older fossils may be proved, by other than palaxmtological 

 evidence, to belong to an older series than those strata which, though an- 

 terior to the basalts, yet contain a fauna decidedly more Pliocene than 

 Miocene in character. This subject may, however, be discussed more at 

 length, from the stratigraphieal point of view, in a succeeding chapter. 



To draw the line between Pliocene and Recent, or to say whether between 



these two groups any distinct series of beds of an intermediate age exists in 



the fresh-water Tertiary of the Sierra,, is a matter of even greater difficulty 



han to separate the Pliocene from a possible lower member of the series. 



seems that the mastodon lived through a portion of the volcanic era, and 



°urished exceedingly down to a geologically recent period. The elephant, 



011 tlx e other hand, has not been detected in the beds below the basalt, so fir 



a s the writer can learn. That the fauna associated with these animals was 



entirely different from that now living in the same region is beyond doubt. 





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