170 
OIL DISTRICTS OF SOUTHERN CALIFORNIA. 
STRUCTURE. 
The most important structural feature in the central field is a line 
of disturbance which extends from the region 100 feet or so north of 
the corner of Patton and Temple streets westward to a point on Ben¬ 
ton street about 200 feet south of First. (See PL XX, sec. E-F.) Near 
this last point it bends and passes to the northwest toward Colegroove. 
This structural feature is in alignment with the fault along the north 
side of the eastern field, and is probably a continuation of it. In 
fact, the only stretch of territory over which it can not actually be 
traced is that lying between the corner of Sumner place and Belle¬ 
vue avenue, northwest of the Sisters’ Hospital, and a point north of 
Temple street near Patton. Throughout this stretch and north 
and south of it for some distance the beds all dip to the south at angles 
varying from 8° to 35°, and no evidences of folding or important 
faulting were observed. 
The anticlinal structure of the flexure is attested by the fact that 
the beds dip to the south on Court street near Lake Shore avenue 
and to the north two blocks farther north. The more or less irregular 
position of the beds in the axis of this anticline near the corner of 
Temple street and Lake Shore avenue indicates that considerable 
faulting accompanied the folding. The exposures on Sumner place 
between Sunset boulevard and Bellevue avenue, in the region north¬ 
west of the corner of Patton and Temple streets, on Burlington avenue 
200 feet or so south of Temple, and on Benton street about 200 feet 
south of First offer further evidence in favor of the fault theory. 
The southern or productive limb of the anticline, although much 
the steeper, shows more regularity throughout the central field than 
the northern limb. It is considerably broken and irregular at its 
east and west ends, but these conditions are probably due to other 
lines of disturbance crossing its strike. The dips near the axis of 
the anticline are usually low, becoming steeper toward the south. 
The oil appears to accumulate in the steeper beds just below the point 
where they bend to the lesser dips near the axis. This is well shown 
in fig. 13, a section along C-F, PI. XVIII, across the field near Lake 
Shore avenue. The dips in the southern limb of the anticline in 
the east end of the field vary from 10° to 45°, becoming abruptly 
steeper toward the east end and reaching a maximum of 70° near 
the corner of Bellevue avenue and Victor street, just west of the 
Sisters’ Hospital. This marked change in the dip is doubtless in 
some way related to the line of disturbance described in discussing 
the structure of the eastern field (pp. 163-164) as extending south¬ 
ward from the corner of Sunset boulevard and Sutherland street 
toward the Sisters’ Hospital. To the west of Belmont avenue the 
dips become steeper, some of them being 70° or more, and the breadth 
of the field decreases in a corresponding manner. The productive 
