DETAILS OF THE DEVELOPED TERRITORY. 
105 
anticline is believed to be that shown on the map (PI. I, in pocket); 
from the evidence offered by the logs of the Hill and Logan wells the 
axis of the anticline, so far as it affects the oil-bearing beds of this part 
of the field, might better be drawn through Hill well No. 1, extending 
westward and eastward (swinging to the north in both directions) to 
the points where the “ surface” anticline passes from the Fernando 
to the Monterey. In either location, however, the anticline has a 
steeply dipping northern flank and a low-dipping and probably undu¬ 
lating southern flank. 
A fault, clearly seen on the east side of Cebada Canyon and traced 
by deposits of asphaltum over portions of the rest of its course, 
extends from a point a short distance east of Cebada Canyon north¬ 
westward at least as far as the brea deposits near Wise & Denigan 
well No. 1. This is clearly a reverse fault in the Cebada Canyon 
region, supposed Monterey diatomaceous shale being thrust up on the 
north over Fernando sandstone which lies south of the line, the dip 
of the fault plane being about 30° toward the north. Mr. Orcutt 
suggests that this fault probably causes the difference in yield be¬ 
tween Hill wells Nos. 2 and 3. The sand is struck about 700 feet 
lower in No. 3 than in No. 2, and is barren in the former but produc¬ 
tive in the latter. The dip in the strata (if the anticline affecting 
the oil sands passes south of well No. 2) might account for the differ¬ 
ence in depth of the oil sand in the two wells, but it alone would 
hardly account for the difference in saturation of the sands. It is 
quite possible that the fault (which theoretically emerges somewhere 
near Hill well No. 4) passes downward at such an angle as to cut the 
oil sand between Hill wells Nos. 2 and 3, throws the sand down on the 
north, and, while acting as an outlet for the oil in the sand for some 
distance on its northern or upper side, effectively seals up the trun¬ 
cated end of the same sand on its southern or lower side. This 
hypothesis assumes a downthrow on the north, a condition exactly 
opposite to that shown at the surface in Cebada Canyon. Alternate 
upthrow and downthrow on the same side of a single fault occurring 
at different times are not unusual in the Coast Ranges, so that such 
an explanation is not only possible but probable. To conform to the 
prevailing conditions the downthrow must have been on the north 
in pre-Fernando and on the south in Fernando or post-Fernando 
time. 
The logs of the Wise & Denigan wells indicate a more or less local 
anticline in the Monterey. Its axis passes near well No. 2 of this group, 
and probably extends in an east-west direction parallel to the major 
lines of structure in the hills immediately to the north. This occur¬ 
rence suggests the probable gentle folding of the Monterey in the 
region south of the Purisima Hills, in a manner similar to that which 
takes place under Burton Mesa farther west. 
