The Origin of the Desert Climax and Climate 115 



Of the six formations considered, only the Manix falls within 

 the desert proper, being more or less central in the Mohave. The 

 Bautista is scarcely beyond the western end of the Colorado. In 

 summing up the evidence for the Manix, Buwalda concludes that 

 the climate in the region and to the west was less arid than at 

 present (1914:457). As to the Bautista, at present this region is 

 grassland under a rainfall thrice as great and hence the difference 

 between Pleistocene and modern conditions was probably less. 

 The mammals of the McKittrick, which is in the "desert" of the 

 upper San Joaquin Valley with a rainfall of 6 inches, are nearly 

 identical with those of the Manix; the genera are all found in 

 the Rancho La Brea and all but one at Fossil Lake, Oregon, indi- 

 cating a general similarity of climate over this wide range. 



The ungulates of Rancho La Brea suggest conditions not 

 much unlike those of the present; the antelope and deer are still 

 found in the general region, and within the historical period 

 both the bison and the reintroduced horse thrived in grassland 

 of less rainfall. Dice (1925:123) believes that the similarity in the 

 rodents indicates that there could have been no considerable or 

 widespread difference in climate between the Pleistocene and 

 the present. On the contrary. Miller thinks that the evidence 

 from the birds, though inconclusive, points to a warm moist 

 climate during the glacial period (1925:70). Hay reaches the 

 conclusion that the Brea deposits were laid down in the Af tonian 

 interglacial stage of the early Pleistocene, when the climate was 

 warm (1927), though this term may well be relative to the 

 Nebraskan and Kansan glacial stages that preceded and fol- 

 lowed. The indications at Carpinteria are essentially the same as 

 at Rancho La Brea, and at both places the rodents and ground 

 birds are nearly all those of the present (Wilson, 1934; L. H. 

 Miller, 193 1 ; A. H. Miller, 1932). 



