130 DELOS AND RALPH ARNOLD 
province: Pecten expansus, Pecten subventricosus, Opalia varicostata 
and Opalia anomala. This lower horizon is correlated with the 
Deadman Island Pliocene. The upper horizon is characterized 
by Pecten hemphill, Crepidula grandis, Macoma secta, Echinarach- 
Fic. 4.— Section along Pacific Beach, near San Diego, showing the relation 
between the San Diego formation (Pliocene) and the upper San Pedro series (Pleis- 
tocene). 
nius excentricus and Strongylocentrotus purpuratus, and is corre- 
lated with the lower San Pedro series (Pleistocene). 
A formation similar to that of the Pacific Beach Pliocene 
outcrops near the Russ School, in the northern part of San Diego. 
The San Diego well, which is located just south of this outcrop, 
gives an instructive section of this Pliocene series. The well is 
at the bottom of a ravine (see Fig. 5), the sides of which are of 
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Fic. 5.— San Diego. Section from San Diego well to bay at foot of Twenty- 
sixth street, showing relation of San Diego formation (Pliocene) to upper San Pedro 
series (Pleistocene). 
strata containing a fauna similar to that of the upper Pliocene 
horizon at Pacific Beach. The strata above the well dip gently 
south toward San Diego Bay. The well is 149 feet deep,’ and 
*The writers are indebted to Mr. Henry Hemphill, who collected fossils from the 
San Diego well during the course of its excavation, for the data concerning it. 
