124 DELOS AND RALPH ARNOLD 
Dr. Dall* says of this Pliocene horizon: ‘It appears that 
on Deadman Island, near Point Fermin, at least three dis- 
tinguishable strata appear, the uppermost of which is certainly 
Pleistocene, while the others are Neocene, and the middle layer 
probably Pliocene.” 
The brown Pliocene sandstone formation outcrops at Timm’s 
Point (see Fig. 2), on the western side of San Pedro Bay. 
Here it lies unconformably on the Miocene shales as at Dead- 
man Island; but its stratigraphic relation with the overlying 
lower San Pedro (Pleistocene) beds is not so easily determinable, 
although the faunal break between the two formations is as pro- 
nounced as at Deadman Island. 
Pleistocene: the San Pedro sertes—The evidence brought 
forward in this paper demonstrates that most of the marine 
Pleistocene as developed on the Pacific coast is represented by 
the strata of Deadman Island and San Pedro. The writers, 
therefore, propose the name San Pedro series for all of the 
strata of Deadman Island and San Pedro lying stratigraphically 
above the brown Pliocene sandstone formation and below the 
raised beach formation of Deadman Island. The San Pedro 
series may be divided into two distinct horizons, a lower and an 
upper, separated at all points in the vicinity of San Pedro by 
an unconformity. 
Lower San Pedro series —A stratum of gray sandstone aver- 
aging about twelve feet in thickness rests unconformably upon 
the brown Pliocene sandstone at Deadman Island (see Fig. 1). 
This gray sandstone is incoherent in some places but very 
firmly cemented in others, the harder portions usually being the 
more fossiliferous. No bedding is visible in the gray sand, but 
the formation lies nearly horizontal. This lower San Pedro 
stratum at Deadman Island, and also the contemporaneous 
strata in the San Pedro bluffs (see Fig. 2), as indicated by their 
lithologic characters and fauna, were deposited in water shal- 
lower than that in which most of the underlying brown Pliocene 
™W. H. DALL and G. D. Harris, Correlation Papers: Neocene. U.S. Geol. 
Surv., Bull. No. 84, p. 216, 1892. 
