892 W. LINDGREN—F. H. KNOWLTON 



"similar to that of the Reed mine near Deadwood. This 'choc- 

 olate' contains leaves of deciduous and coniferous trees in toler- 

 ably good preservation." Now, Bowen's channel, correctly 

 described above, is a typical example of the narrow valleys 

 eroded shortly before the main andesitic outflows, and its flora is 

 distinctly later than that of the Chalk Bluffs and Independence 

 Hill and just antedates the main andesitic tuffaceous breccia 

 flows. Lesquereux^ describes the following species from this 

 locality : 



Quercus Boiveniana Lx. Resembles certain living Mexican forms. 

 Rhus Boweniana Lx. 



Zanthoxylon diversifoliiim Lx. Closely related to Z. ifitegrifoHum Heer 

 (Swiss Miocene). 



Acer vitifoliimi Al. Br. (Swiss Miocene). 



The conifer leaves, mentioned by Whitney, do not appear to 

 have been determined. Though meager, this flora is evidently 

 closely connected, if not identical with that from the bench 

 gravels and is probably Miocene. Still another locality men- 

 tioned by Professor Whitney is that of North Fork tunnel near 

 Forest City, Sierra county. From the description of Professor 

 Pettee (Auriferous Gravels, p. 437) it appears that the leaves 

 found occurred in a sandy clay resting on a gravelly "cement" 

 and directly covered by andesitic tuff. It is not quite clear 

 whether by this "cement" is understood a volcanic tuff, but in 

 any case it seems plain that the leaves could have antedated 

 the andesitic tuff but a short time. This occurrence, which is 

 considerably above the deepest gravels of the vicinity and not 

 now accessible should probably also be connected with the 

 inter-volcanic period of erosion. The elevation of this locality 

 is nearly 5000 feet. The leaves are species of Quercus and Acer 

 and Lesquereux remarks that it is Miocene by one species of 

 Quercus and one of Acer, while it also has of each of these one 

 species identical or closely resembling certain living Mexican 

 forms. 



While the flora of the gravels of the inter-volcanic erosion 

 ■ Report on the Fossil Plants : Appendix to Whitney's Auriferous Gravels. 



