

- y 



234 



THE ATTEIFEROUS GKAYELS OF THE SIEREA NEVADA, 



all the other 



flcxilis 



which however occurs chiefly in scattered clumps, marking the upward limit 

 of vegetation, but hardly forming a distinct zone. 



If now we inquire whether any arrangement or order of succession, of a 

 character similar to that just indicated for the present vegetation, can be 

 traced in that of the auriferous gravel series, we have, in the first place, to 

 confess to poverty of material necessary for giving a definite answer. Still, 

 what evidence has thus far been collected is decidedly in favor of a uniformity 

 of vegetation, rather than of variety or separation into zones, during the 



epoch of the gravels. 



In illustration of this statement, the entire absence of any proof of the exist- 

 ence of coniferous trees during the gravel period may be brought forward. 

 In none of the collections made, so far as the same have been examined by 

 Mr. Lesquereux, have any traces of the existence of conifers been observed. 

 Neither has the writer any recollection of having observed such in his inves- 

 tigations in the gravel region. Although further examinations may bring to 

 light proofs of the former presence of coniferous trees in some portions of the 

 gravel deposits, it seems almost certain that, if existing at all, they must 

 have been very subordinate to the deciduous vegetation. 



We have now to inquire in regard to the vertical range of the fossil plants 

 collected and examined by Mr. Lesquereux. Although leaves have been 

 observed in many localities, as has already been explained, extremely few of 

 these have yielded material in sufficiently perfect state for description. By 

 far the most prolific locality is that of Chalk Bluffs, and the one next to it in 

 importance is the Tuolumne Table Mountain. These two places arc separated 

 from each other by a distance of somewhat over eighty miles j the former is 

 in latitude 39° 12', the latter in 38°. Bowen's Claim, the next locality in im- 

 portance, is fifteen miles south-southeast of Chalk Bluffs. The difference in 

 altitude between the two principal localities is, however, considerable, the 

 plant-bearing beds of Table Mountain being about 2,000 feet in elevation, 

 and those of Chalk Bluffs from 3,500 to 3,600 feet, the difference between the 

 two being fully 1,500 feet. The fossil flora of the localities, thus seen to be 

 considerably different both in latitude and altitude, would seem 



from the 



investigations of Mr. Lesquereux 



to be essentially the same. That is, 



nearly the same genera are represented, although the species are, in most 

 cases, considered as differing. From the annexed tabular view of the species 

 described by Mr. Lesquereux, in which the localities are designated, it will 



