120 
OIL DISTRICTS OF SOUTHERN CALIFORNIA. 
BREA CANYON FIELD. 
LOCATION. 
Brea Canyon finds exit from the Puente hills 5 miles north-northeast 
of Fullerton in the vicinity of one of the most important oil districts 
in the territory. Below the forks the canyon assumes the trend of 
the main Puente anticline and lies close to the zone of maximum dis¬ 
turbance. At a point where the beds have been locally crushed it 
cuts directly through the outer terrane of the hills and passes into the 
valley. (See PI. XIV, A.) 
GEOLOGY. 
The Brea Canyon oil field is developed in the zone of highly dis¬ 
turbed strata along the lower canyon in a general N. 65°-70° W. direc¬ 
tion. The formations include the Fernando conglomerate, sandstone, 
and arenaceous clay, the upper shale of the Puente, the Puente sand¬ 
stone, here limited in area, and the lower division of the Puente, with 
its shale, interbedded sandstone, and lenticular masses of limestone. 
The Fernando formation is well exposed along the lower portion 
of Brea Canyon. The higher and outer members consist of bright 
gray and yellow conglomerate, sandstone, and arenaceous clay. 
Within and lower in the series conglomerate becomes somewhat 
less conspicuous and traces of bitumen begin to appear. This fea¬ 
ture is especially noticeable at the entrance to the canyon proper. 
Here also the sandstone, with a few pebbles, shows the concretion¬ 
ary structure observable elsewhere in the hills, but the formation is 
not on this account to be confounded with the Puente sandstone, 
for otherwise there are marked lithologic differences, and in addition 
to these the fossils of the younger beds are especially abundant and 
characteristic. The conglomerate of the Fernando formation enters 
largely into the composition of Brea Bidge, extending eastward far 
beyond the region of the Santa Fe wells. Westward it may be 
traced to its disappearance beneath the valley opposite the Puente 
oil field. Still lower in the series and occupying the inner or north¬ 
ern slope of Brea Bidge are several bands of petroliferous sand¬ 
stone that display a few concretions and here and there a pebble 
mass and are interbedded with arenaceous clay. Two of the sand¬ 
stone bands are particularly conspicuous, one well down on the 
north face of the ridge, the other north of the ridge near the creek 
channel. It is possible that these may lie at the same horizon, but 
that they are duplicated by faulting, the valley of the creek being 
coincident with a line of marked local disturbance. These beds 
carry fossils of lower Pliocene age. (See list, p. 107.) In the hill 
north of Brea Canyon there is a further succession of beds of clay, 
sandstone, and conglomerate, one or two of the conglomerate beds 
