68 R. W. Chancy 



tensive quantitative studies involving a comparison of the fre- 

 quency of occurrence of leaves and fruits in Tertiary deposits and 

 in contemporary stream deposits have been carried on by the 

 writer in the past fifteen years. From numerous localities, of 

 both Miocene and Recent deposition, a large amount of data has 

 been compiled which shows that Alnus, Quercus (Lithocarpus), 

 Sequoia, and Umbellularia made up the same dominant ele- 

 ment in the redwood forest of the Miocene as these genera do 

 today. A count of 20,611 fossil specimens from the type locality 

 of the Lower Miocene Bridge Creek flora, in the John Day Basin 

 of eastern Oregon, has shown that four fossil species of the 

 above-named genera make up 86.44 per cent of the total; a count 

 of 8422 modern specimens from a valley in Muir Woods, near 

 the coast of central California, has shown that the four modern 

 equivalents of these genera make up 85.44 per cent of the total." 

 The general aspect of the Miocene forest, particularly in the 

 early part of the epoch, must have been strikingly similar to that 

 of the redwood belt on the California coast. A survey of the fol- 

 lowing list of the common families and genera of the Miocene 

 floras of western North America will emphasize, however, the 

 presence of two important elements which are no longer domi- 

 nant or present there. 



Ginkgoaceae Tsuga 



Ginkgo Taxodiaceae 



Taxaceae Glyptostrobus 



Taxus Sequoia 



Torreya Taxodium 



Pinaceae Cupressaceae 

 Abies Libocedrus 



Picea Thuyites 



Pinus Liliaceae 

 Pseudotsuga Smilax 



