1912] Miller: Pacific Coast Avian Palaeontology 



83 



less than two hundred feet above its level. The locality is today 

 a typical open valley country, protected on the north by the 

 east-and-west Santa Monica Range, yet tempered by the cool 

 and moisture-laden breeze from the sea. Faunally, the locality 

 lies in the Upper Sonoran zone of the San Diego region. 



The Shasta caves occupy a position further inland and seven 

 degrees to the northward of Rancho La Brea. Their elevations 

 vary between 1300 and 1500 feet above sea-level. The isothermic 

 zone represented is slightly above that of Rancho La Brea, it 

 being Upper Sonoran and lower Transition. The isohumic area 

 is that of the Sacramento-San Joaquin, which is an area of 

 slightly greater precipitation than is the San Diegan. 



The two localities are at present distinguishable in their avi- 

 fauna by the presence or the absence of several species which 

 are of interest in the light of palaeontological records. The 

 entire group of grouse, represented in the Shasta region by 

 Dendragapus, is wanting at Rancho La Brea. Oreortyx and 

 Cyanocitta, present in the cave region, are wanting in the im- 

 mediate vicinity of the asphalt beds. Geococcyx, present in the 

 latter locality, is wanting in the former. 



These, however, are birds of slight volant power. The species 

 of less restricted activity, such as the Raptores and the water- 

 birds, are common to the two localities at present. 



The Fossil Lake region of Oregon lies in latitude 43° N, full 

 nine degrees north of Rancho La Brea, and is on the eastern 

 side of the Cascade Range. This separation from the coastal 

 slope would influence the smaller species of birds more than the 

 larger. Winter temperatures would be more severe, with sum- 

 mer temperatures fully equal to those of southern California. 

 The rainfall at the present time is such as to give the region 

 the name of "Oregon Desert." 



There appears, then, as distinguishing the five more import- 

 ant localities today, a difference of nine degrees of latitude, a 

 range of elevation from 100 to 1500 feet above the sea, and a 

 faunal difference limited to the Upper Sonoran and lower 

 Transition zones. There is no evidence of marked change in 

 elevation since Pleistocene times; hence it seems probable that 

 a somewhat similar relationship between the localities prevailed 



