SOUTHERN PACIFIC LINES 277 
northeast corner of the Puente Hills. A section of the San Jose Hills 
north of Walnut is given in Figure 67. 
The Puente Hills consist of sandstones and shales of the Puente 
formation,” 2,600 to 3,400 feet thick (middle and upper Miocene), 
with smaller exposures of underlying and interbedded shales, having 
the relations shown in Figure 68. The granites and slates of pre- 
Cretaceous age at the east end are separated from the sandstone 
member of the Puente by tuffs and tuffaceous sandstones, somewhat 
as shown in the lowest section in Figure 68. The Puente formation 
of this region (regarded as equivalent to the Modelo formation of the 
region to the west) is made up of an alternating succession of coarse 
and fine materials with many thick members of shale and sandstone. 
The upper shale includes beds carrying the remains of minute marine 
plants and animals, principally diatoms and Foraminifera; the more 
richly diatomaceous portion is nearly white and of chalky texture. 
SSE. 
andsto NNW, 
ict BS: aati Un ceees 
Vertical and horizontal scales 
° 5,000 10,000 Feet 
l iL. i. i. i i 
x § 
wz 
L 
FIGURE 67.—Section of San Jose Hills about 7 miles west of Pomona, Calif. After English and Kew. 
All Puente formation 
At the west end of the hills, south and west of Puente, overlying shales 
and sandstones of the Fernando group (Pliocene) are extensively 
exposed, and they are dropped by a fault extending along the south 
side of the Puente Hills, passing just north of Whittier and along 
La Habra, La Brea, and Olinda Canyons. The Fernando group 
carries a fauna of marine shells of Pliocene age and is nearly 5,000 
feet thick. (English and Kew.) 
On the upper slopes of the western part of the Puente Hills, about 
5 miles southwest of Walnut, was the old Puente oil field, one of the 
% According to the definition of the Sandstone member, 300 to 2,000 
Puente formation by the U. S. Geolog- feet. Moderately coarse gray 
ical Survey, in the Puente Hills and Los to tawny-yellow thick-bedded 
Angles district it comprises the follow- sandstone with beds of shale; 
ing members: some conglomeratic bers 
Upper shale, 300 to 2,000 feet. containing granite boulders. 
hy chalky shale and sandy Lower shale, 2,000 feet. Chiefly 
gray shale, weathering pink to rthy shale, mostly gray to 
chocolate-brown, with a few black, including thin beds of 
beds of fine yellow sandstone. | fine-grained sandstone from top 
Is overlain unconformably by to base and lentils of limestone. 
Fernando group, 
