LOS ANGELES DISTRICT: CENTRAL FIELD. 169 
A typical log for the part of the central field lying near Belmont 
avenue is as follows: 
Log of well at corner of Belmont avenue and First street, Los Angeles. 
[Elevation approximately 400 feet above sea level.] 
Thick¬ 
ness. 
Depth. 
Fed. Feet. 
Clayey and sandy shale. 850 850 
Clayey shale with interbedded oil producing sand (“stray ” sand). 50 900 
Good oil sand, medium to coarse. 100 1,000 
Clayey shale. 40 1.040 
Oil sand. 70 1,110 
White sand with salt water. 10+ 1,120+ 
In the region between Burlington avenue and Alvarado street the 
dip is steep, the oil sand being struck at about 700 feet on the north 
side of the productive belt, 900 feet in the middle, and 1,100 feet at 
the south edge. The strata above the oil sand consist largely of 
dark-colored shale and thin-bedded sandy layers, the latter occasion¬ 
ally petroliferous or water bearing toward the'base of the section. 
Owing to the steep dip in this part of the field, the wells remain in the 
oil sand for a much greater distance than thev do farther east. There 
are also indications of a tendency toward coalescence of the oil sands 
here, caused by a partial pinching out of the shale beds. One well 
near the north side was chilled for over 300 feet through productive 
sand, with only a few thin layers of shale. The water plane in this 
portion of the field appears to be almost level, being struck at a depth 
of about 1,200 feet on the north side and 1,250 feet on the south side. 
The water is salt, and displaces the oil in the sandy beds below these 
depths. 
From Alvarado street westward to the end of the field the beds dip 
at angles varving from 50° to 70°, and the width of the field is re- 
duced to a minimum of 300 feet. The strata are practically the same 
as those penetrated east of Alvarado street, the only difference being 
that the water plane is a little lower—at a depth of about 1,300 feet— 
and the wells are in consequence a little deeper. The wells here 
are said to be the most productive in the field, some of them having 
yielded 60 barrels a day at the start and kept up a steady production 
of 20 barrels for at least a year. Owing to the steepness of dip and 
the close proximity of the wells to the structural disturbance at the 
bend in strike, which occurs only a short distance west of the west 
end of the field, considerable difficulty is experienced from caving. 
Toward the northern edge of the field the wells go to 1,200 feet and 
obtain o-ood results, but much water is encountered in manv of the 
beds above the 700-foot level. At the south edge of the field the 
productive zone, which extends from a depth of 1,000 or 1,100 feet 
to the water plane at 1,300 feet, consists of clayey shale interstrati- 
fied with oil-bearing “stray" sands. 
