FAUNAL RELATIONSHIPS OF THE MEGANOS GROUP 129 
same period of deposition as the typical Tejon; they did not recog- 
nize their Oliqua in California; the Arago formation was corre- 
lated with the Ione along the Sierra Nevada front. Arnold and 
Hannibal agree with Dickerson in placing the marine beds of the 
Ione as uppermost Eocene in age, but disagree in that they con- 
sidered this horizon to belong to a distinct epoch of deposition. 
The following statements are taken from the paper of Arnold and 
Hannibal: 
The writers have shown that in Oregon and Washington the Eocene may 
be divided into three faunal divisions, the Chehalis, Oliqua, and Arago or 
Ione formations. The Chehalis formation is characterized especially by 
Venericardia hornit Gabb, Meretrix californica Gabb, and an austral flora, 
the Oliqua formation by Pecten (Chlamys) landesi or Venericardia hornit Gabb 
and a tropical flora, and the Arago or Ione formation by Turriiella merriamt 
Dickerson, a form of V. hornii with obsolete ribs (var. aragonia A. and H.), and 
a tropical flora. 
The Arago or Ione beds represent a horizon younger than any Tejon 
recognized in the Tejon or Puget Basin. The Arago or Ione beds occurring as 
they do in basins distinct from those in which the Tejon series is developed, 
and being formed at a different period, must be treated as a distinct division 
of the Eocene. 
Professor C. E. Weaver in his study? of the Eocene sections of 
the Cowlitz River Valley, Washington, the section studied by 
Arnold and Hannibal and where they described their Chehalis 
horizon as being below the Oliqua, disagrees with them as to the 
sequence. His stratigraphic study of this section apparently 
shows that the beds of the Oliqua formation are below those of 
the Chehalis; in other words, Arnold and Hannibal had their 
section upside down, a condition similar to that which existed in 
California. 
The first published announcement by the writer of his dis- 
covery that there are three distinct groups of strata in the Eocene 
section of Mount Diablo appeared in a paper to which reference 
has been made. It was not until this paper was in page proof 
™ Ralph Arnold and Harold Hannibal, “Dickerson on the California Eocene,” 
Science, new series, Vol. XX XIX (1914), No. 1016, p. 607. 
2C. E. Weaver, ‘“‘Eocene of the Lower Cowlitz River Valley of Washington,” 
Proc. Cal. Acad. Sct., 4th ser., Vol. VI (1916), Nos. 1, 2, and 3, pp. I-17. 
3 Bruce L. Clark, ‘‘Meganos Group, a Newly Recognized Division in the Eocene 
of California,” Geol. Soc. Amer., Vol. XXIX (1918), pp. 281-96. 
