SANTA CLARA VALLEY : OJAI VALLEY FIELDS. 
37 
between 1,000 and 2,000 feet thick, of red and white sandstones which 
seem to belong to the Sespe formation. Between the southerly belt 
of rusty beds, which are regarded as Yaqueros, and the Modelo shale, 
which constitutes Thompson Ridge, there is unquestionably a fault 
the throw of which can hardly be less than 2,000 feet. The Thompson 
Ridge fracture is more directly in line with the San Cayetano fault to 
the east than any of its associates and it may be responsible for the 
existence of both the Upper and Lower Ojai valleys. To the east it 
passes immediately south of the wells of the Bard and adjacent oil 
companies. Between the Lower Ojai Valley and Santa Paula Canyon 
the thickness of the red beds is greatly reduced, and to the south the 
rusty beds may almost entirely disappear, for in the Silver Thread dis¬ 
trict the outcrop of these two strata is less than 300 feet thick. From 
the trend of the formations north of the Lower Ojai and from litho¬ 
logic similarities, it is inferred that the great development of rusty 
beds north of the Bard and Capital Crude wells is continuous with 
those of the Topatopa formation in the lower slopes of the Topatopa 
Range to the west. At this point these beds have furnished a fair 
collection of fossils, which are regarded as Eocene. In this connection 
it is worthy of notice that at the head of the Lower Ojai Valley the 
rusty beds south of the red beds carry fossils that were, with equal 
certainty, determined as lower Miocene. 
The Modelo shale, forming Thompson Ridge, is severely crumpled 
and is probably an included fragment of siliceous shale. It disap¬ 
pears beneath the wash of the Lower Ojai Valley and has every evi¬ 
dence of wedging out a little west of the Silver Thread district. - 
South of this interfault block of Modelo there is a narrow band of 
rusty beds, which also wedge out to the east. These beds have every 
appearance of the Yaqueros formation and carry the same fossils as 
those north of the Modelo block. They border Thompson Ridge on 
the south and pass at once into the Lower Ojai Valley, where they 
disappear beneath the later wash. This block of rusty beds presents 
a variety of dips and strikes, and it is thought, therefore, to be sim¬ 
ply an inclined fragment between the great faults of the region. The 
fracture separating it from the red beds bordering it on the south is 
recognized as passing the valley road at the head of the gorge between 
the Lower and Upper Ojai basins to the west, following the line of a 
short gulch to its junction with the general valley. It is probable 
that in this direction it has been the northern determinant of Lion 
Ridge. To the east the fault seems to pass in a direction about S. 
80° E., merging finally with one or another of the greater fractures 
of the system. 
It is interesting, also, to note the occurrence of a narrow strip of 
rusty beds included in the Modelo shale in the easterly portion of the 
crest of Thompson Ridge. 
Bull. 309 -07 ——4 
