PALEONTOLOGY. 401 



several horizons show the same group of dominant species, indicating a recur- 

 rence at least twice of conditions suitable for the development of the Upper 

 Clarno forest. The local abundance of Sequoia may be interpreted as indi- 

 cating the presence of relatively humid habitats in which this genus pre- 

 dominated. 



The study of the Payette flora from western Idaho indicates the Miocene 

 age of the Payette formation. Although related to the Mascall flora of the 

 John Day Basin, the Payette shows certain characteristics which indicate a 

 greater aridity and a higher relief than are presumed to have existed in central 

 Oregon during the Miocene. Such climatic and topographic variations over 

 distances of a few hundred miles may be expected to have existed then as 

 they do now. 



Collections from western Nevada indicate the importance of this area in 

 correlating the Tertiary section of the Great Basin with those of the Coast 

 Ranges and the Auriferous Gravels. There is reason to believe that a much 

 more extensive record of the Tertiary plants of this critical area will be found 

 during subsequent field seasons. 



Through the help of Dr. F. E. Matthes, my attention has been directed to 

 a fossil-leaf locality in the Auriferous Gravels at Table Mountain, Tuolumne 

 County, California; vertebrate remains were also secured in the same general 

 region. The plants occur in a layer of andesitic tuff associated with gravels, 

 both overlying the grano-diorite bedrock. Of the 16 species, 9 are known 

 only from the flora of the Auriferous Gravels; 2 species are restricted to the 

 Eocene and Oligocene, 3 range from the Eocene into the Miocene, and 2 are 

 restricted to the Miocene. Of these latter, Platanus dissecta is one of the 

 most widespread and characteristic forms of the Miocene. The total lack of 

 knowledge regarding the Pliocene plant life in the West makes it impossible 

 to be certain that the Table Mountain flora is not of Pliocene age, the age 

 indicated by the associated mammalian remains. Considering that the 

 Pliocene flora is practically unknown, the flora would probably be recognized 

 as Miocene. 



Numerous short trips have been made to fossil-plant localities in the Coast 

 Range region near Berkeley. On one of these a forest of petrified Sequoias 

 was visited in company with Doctors Day and Allen, of the Geophysical 

 Laboratory. While the fossil floras of this province do not show the variety 

 and excellence of preservation which characterize those of the Great Basin, 

 they will ultimately be of great value in correlation since they are associated 

 in the Tertiary section with numerous invertebrate faunas whose age is known. 



A trip from Berkeley to Agate, Nebraska, in company with Dr. Frederic 

 E. Clements, resulted in the discovery of a considerable amount of silicified 

 wood. Plans are already under way to utilize this type of material in check- 

 ing generic determinations based on the leaves. Studies of the origin of 

 Tertiary sediments were made, especially in that portion of the territory east 

 of Salt Lake City, where Dr. W. D. Matthew was a member of the party. 



Mr. Robert H. Seashore, of the State University of Iowa, acted as field- 

 assistant during the greater part of the summer. 



