Diller— Klamath Mountain Section, California. 359 



than to say that the Trinity leaves are similar in age to a part of 

 what has been called the Auriferous Gravels. 



" No. 6168. Hay Fork Creek, one and three-quarter miles west 

 of town of Play Fork. A considerable collection of material, the 

 matrix being a soft sandstone. 



The following are represented : 



Juglans Schimperi Lesq. 

 JPopulus Heerii Lesq. 

 Rhamnus? sp. 



The first species is present in great abundance and in perfectly 

 typical examples, while the last (Populus Heerii) is so closely 

 similar to the type that it might almost have been the original 

 from which the figure was made. I state this for the purpose of 

 showing that there can be no question as to their identification. 

 These two species are found at Florissant, Colorado, and should 

 be referred to the upper Eocene. 



I think the material from this locality is probably the same as 

 that which I reported on last year, referring it with hesitation to 

 the upper Miocene. Only two species were present in that col- 

 lection and both are of general distribution throughout the Ter- 

 tiary. With the present collection the matter is different ; the 

 forms recognized are clearly older, and I am forced to the conclu- 

 sion that there must be two horizons represented in the Hay Fork 

 area." 



The new points concerning the Hay Fork beds brought out 

 by this collection are : (1) The determination of the supposed 

 shark's teeth as fruit of a fresh water plant removes the chief 

 argument tending to show that the Hay Fork beds were formed 

 in an estuary near sea-level. (2) The Hay Fork beds are now 

 not only more definitely correlated to the Auriferous Gravels 

 but with a portion of them of upper Miocene age. (3) The 

 recognition of Eocene forms is somewhat of a surprise. In the 

 field all the beds in Hay Fork Valley were supposed to be of 

 the same age. The layers containing the upper Miocene forms 

 (6170) are from the west and lowest end of the valley and 

 without intervening Eocene beds rest directly with marked 

 unconformity on the adjacent Paleozoic rocks. 



Pliocene. 



Along the northern side of Hay Fork Valley there is a mass 

 of white tuff at least 15 feet in thickness which is closely 

 related to a similar deposit in the Pedding Creek basin of the 

 same region. These deposits are of but little importance as to 

 size, but as a time-marker they may become important in cor- 

 relating the sediments of independent basins. Considering 

 the size of the deposit, its distribution and the general charac- 

 ter of the material, its source is believed to be Lassens Peak, 



