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University of California Publications in Geological Sciences 



are areas where the Verdi shows relationship to modern vegetation. The available 

 data, although incomplete, suggest that on the basis of its geographic relations to 

 modern vegetation the Verdi flora is not older than Late Clarendonian, and is more 

 probably of Hemphillian age. 



Climatic implications. — Late Tertiary plants are scarcely distinguishable from 

 living species, and most of them formed communities that closely resemble modern 

 associations. The physical conditions under which these related communities now 



TABLE 7 



Cliseral, Geographic, and Climatic Relations of Tertiary 

 Vegetation in Western Nevada 



Age 



Kinds of vegetation at 

 site of deposition 



Regions with related 

 modern vegetation* 



Climate 



Pliocene 



Riparian woodland 



Oak woodland and savanna; 

 Chaparral 



Nearby region; southern 



California 

 Central-southern California; 



southwestern United States 



Semiarid 



Mio-Pliocene 



Oak woodland, chaparral 



Montane forest 

 Deciduous hardwood forest 



South-central California; 



southwestern United States 

 Sierra Nevada to Rocky Mts. 

 Eastern America, Eastern 



Asia 



Subhumid 



Miocene 



Deciduous hardwood forest 



Montane forest 

 Oak woodland 



Eastern America, Eastern 



Asia 

 Western North America 

 Southwestern North America 



Temperate 



Oligocene 



Warm temperate forest 

 Deciduous hardwood forest 



Southeast China; Gulf States 

 Eastern Asia, Eastern 

 America 



Warm 

 temperate 



Eocene 



Tropical to subtropical forest 



Tropical America and Asia 



Tropical 



» Vegetation types and areas of modern occurrence are listed in order of relative importance for each epoch. 



live not only provide an index to past climate, but also to age. Comparisons of 

 numerous Tertiary floras in the western United States have shown that there was a 

 gradual shift from warm, moist tropical climate early in the Tertiary, to cool, 

 semiarid climate near the close of the period (Chaney, 1938&; 1948). 



Table 7 shows that with respect to climate in western Nevada, Early Tertiary 

 floras were tropical to subtropical, Middle Tertiary floras were humid temperate, 

 and Late Tertiary floras range from subhumid to semiarid. The semiarid aspect of 

 the Verdi flora, as discussed in the preceding chapter, thus demonstrates its Late 

 Tertiary age. A sufficient number of Late Tertiary floras is now known to give us 

 some insight into the details of climate in the far West at that time. In this region 

 there appears to be good evidence for asserting that Early Pliocene climate was 

 considerably moister and warmer than present-day conditions at a given fossil 



