The Origin of the Desert Climax and Climate 119 



The faunistic data for the transmontane area during the Mio- 

 cene are derived from the same locaHties as are those of the 

 Phocene; they are represented by the Barstow, Virgin Valley, 

 and Mascall. These are reenforced by the Cedar Mountain de- 

 posits near Walker Lake in western Nevada, which closely 

 resemble the first two, particularly in the ungulates. According 

 to Merriam (1919:450), the Barstow fauna denotes an open 

 country with much grass and herbage, better watered than the 

 present desert. The abundance of Merychippus, merycodonts, 

 camels, and related forms, indicates that grasses were well rep- 

 resented and hence that the climax must have been grassland. 

 The climate was probably semiarid, like that of parts of the 

 Great Valley today. Likewise, the horses, camels, and meryco- 

 donts of Cedar Mountain suggest a semiarid climate not gready 

 different from that of the region at present, but the other forms 



