608 BRUCE L. CLARK 
Lower Pliocene deposits were laid down. The Lower Pliocene 
in this region is composed of the Pinole tuff and the Orinda forma- 
tion which are of continental origin. 
Faunal relationships of the Pliocene-—Dr. Nomland’s study of 
the faunas of the Jacalitos (“lower Etchegoin’’) and Santa 
Margarita has shown that they are very distinct, and that the 
hiatus between them was more than local.t. None of the highly 
ornamented gastropods, pelecypods, or echinoids has been found 
common to the two, and the percentage of recent species in the 
Santa Margarita is much less than that in the Jacalitos (lower 
Etchegoin) of Nomland. 
An unconformity has been found in the Fernando series in the 
region just north of Los Angeles which is probably the largest and 
most important stratigraphic break in the West Coast marine 
Pliocene? Over a fairly large area in that region there is a marked 
difference in div and strike between the lower and middle Fernando, 
now referred to the Pico formation by the United States Geologi- 
cal Survey, and what has previously been referred to as the upper 
Fernando.3 The beds of this upper horizon contain a very large 
percentage of recent species. The Geological Survey proposes 
to use the name “Saugus formation” for the upper Fernando sec- 
tion. It is herein referred to as the Saugus group. The faunal 
break between the Saugus and the Pico indicates a great lapse of 
time. Indeed, the difference is so great that the question may be 
raised as to whether the Saugus does not belong to the Pleistocene 
J. O. Nomland, “Fauna of the Lower Pliocene at Jacalitos Creek and Waltham 
Canyon, Fresno County, California,” Bull. Dept. Geol., Univ. Cal., Vol. IX (1916), 
No. 14, pp. 199-214; ‘‘Fauna of the Santa Margarita Beds in the North Coalinga 
Region of California,” Bull. Dept. Geol., Univ. Cal., Vol. X (1917), No. 18, pp. 293-326. 
2G. H. Eldridge, and R. Arnold, ‘Santa Clara Valley, Puente Hills and Los 
Angeles Oil Districts of California,” U.S. Geol. Surv., Bull. 309 (1907), pp. 1-250. 
R. Arnold and R. Anderson, “‘ Geology and Oil Resources of the Santa Maria District, 
California,” U.S. Geol. Surv., Bull. 322 (1907), pp. 1-157. W.S. W. Kew, “Struc- 
ture and Oil Resources of the Simi Valley, Southern California,” U.S. Geol. Surv., 
Bull. 691 M (1919), Pp. 323-55. 
3 A paper by Dr. W. S. W. Kew of the United States Geological Survey is now 
in press in which the Fernando is considered a group composed of the Pico and Saugus 
formations separated by an unconformity. 
