1916] 



Dickersoii: Tejon Eocene of California 



387 



This fauna evidently represents the Balanophyllia variabilis zone 

 on the northern limb of the Mount Diablo Anticline. 



Ione Formation of California 



One of the numerous problems of California geology is the cor- 

 relation of the Tertiary of the Sierra Nevada with that of the Coast 

 Ranges. Many geologists since the time of AVhitney have written on 

 the age of the Auriferous Gravels and the associated formations, but 

 the ages of these formations are still in question and their correlation 

 with the marine deposits of the coast ranges is unproven. 



While collecting during the past four years for the Department 

 of Palaeontology of the University of California, the writer has had 

 opportunity for the study of the relationship of the Ione of the 

 Sierra Nevada with the marine Eocene of the Coast Ranges. His 

 conclusions are based upon visits to five typical Ione localities, viz.. 

 Marysville Buttes, Sutter County, California; vicinity of Oroville 

 South Table Mountain; Merced Falls; vicinity of Bear Creek, Mer- 

 ced County; and the type locality near the town of Ione in the Jack- 

 son Quadrangle. 



Conclusions from this study are, that the Ione is, in part at least, 

 marine and of Tejon-Eocene age. Marine fossils have been found 

 in the upper portion of the Ione formation in the four localities 

 visited. Apparently the same faunal zone, the Siphonalia sutter- 

 ensis 40 zone, is represented in these five places. 



In the study of the Eocene of the Marysville Buttes the writer's 

 conclusion was that "the supposed marine lone of Marysville Buttes 

 is evidently Eocene." In the "Note on the Faunal Zones of the 

 Tejon Group," the strata beneath the Older Basalt of Oroville South 

 Table Mountain, which Lindgren mapped as lone, were correlated 

 with the Eocene of the Marysville Buttes. Several of the fossils 

 obtained from the strata beneath the Older Basalt were identical 

 with those of the Marysville Buttes. After visiting these two 

 localities the writer was inclined to the belief that the lone and 

 Tejon had been confused in both these places. Conclusive evidence 

 has recently been obtained in the type locality of the lone which 

 demonstrates that the Ione is merely a local facies of the Tejon- 

 Eocene. 



40 Dickerson, R. E., Fauna of the Eocene at Marysville Buttes, California, 

 Univ. Calif. Publ. Bull. Dept. Geol., vol. 7, pp. 257-298, 1913. Note on the 

 Faunal Zones of the Tejon Group, Univ. Calif. Publ. Bull. Dept. Geol., vol. 8, 

 p. 23, 1914. 



