1918] 



Merriam : 



Age of Lake Lahontan 



519 



Mono to the lowest moraines of the glacier on the east side of the 

 Sierras. If these suggestions are approximately correct, the last stage 

 of Lahontan and Bonneville, approximating the stage of Fossil Lake, 

 would perhaps correspond to the Wisconsin or last glacial epoch. 



In his study of Lake Bonneville, Gilbert gave particular attention 

 to the problem of age determination of the deposits and made careful 

 comparison of the sediments of the Bonneville and Lahontan stage 

 with those of Fossil Lake in south central Oregon. He considered 

 that in the Fossil Lake region, "just as in the Bonneville and Lahontan 

 basins, the physical relations indicate that the shore lines and lacus- 

 trine sediments are co-ordinate products of the same expansion of lake 

 waters." He stated further that "each of the old lakes thus demon- 

 strated stands witness to climatic oscillation, and their geographic 

 relations leave no room for question that they pertain to the same 

 climatic oscillation, and therefore have the same date." 



The evidence of faunas as interpreted by Osborn and by Hay would 

 fix the age of the Fossil Lake deposits as early Pleistocene. In this 

 palaeontologic determination one of the most important arguments is 

 the absence of bison remains from these deposits, which were evidently 

 formed in an open plains region where bison would be expected to 

 occur. This peculiarity is offset to some extent by the fact that the 

 large wolves of the Fossil Lake beds seem to be exclusively of the 

 modern timber wolf type. The great dire wolf, Aenocyon dims, has 

 not been recognized in the Fossil Lake fauna, although it is exceedingly 

 abundant at Rancho La Brea and seems to be represented at Potter 

 Creek Cave. Difference in the types of wolves might be due to the 

 northern origin of the modern timber wolf, and to its restriction 

 throughout Pleistocene time to the northern portion of the West Coast 

 region. Within historic time the timber wolf has not been known in 

 middle and southern California. This would not, however, account 

 for its failure to overlap in range with Aenocyon dints in the Great 

 Plains region. Of the total Fossil Lake fauna 66 per cent of the mam- 

 mals and 34 per cent of the birds are extinct. These percentages are 

 probably not finally determinative of age, but they suggest a stage 

 comparable to that of Hay Springs or Rancho La Brea and earlier 

 than Conard Fissure or Samwel Cave. 



Compared with the Rancho La Brea fauna that of Fossil Lake is 

 characterized by absence of Bison, which are abundant at Rancho La 

 Brea, and were evidently late arrivals in America. This peculiarity 

 is balanced by absence of the small antelope, Capromeryx, and the 



