54 SANTA MARTA OIL DISTRICT, CALIFORNIA. 
LITHOLOGIC CHARACTER. 
This formation is mapped as a unit, although it certainly rep¬ 
resents a long period during which sedimentation, continuous in 
the region as a whole, was locally intermittent and carried on under 
differing conditions, owing to the differential elevations to which 
the region was subjected. The stratum resting upon the Monterey 
in one place is apt to be absent in another, where an overlap of one 
or another stratum may occur. The lowest recognized Fernando 
rocks occur south of Sisquoc, where the Monterey is overlain by a 
bed of brecciated and waterworn shale derived from it and cemented 
by argillaceous sand, above which lies about 200 feet of fine sand, 
succeeded by a 50-foot layer of diatomaceous shale that is indistin¬ 
guishable from that of the Monterey. Above this shale the series 
grades up through about 600 feet of fine white and yellow sand and 
coarse sand, until a bed of conglomerate is reached. At other places, 
as south of Waldorf and south of Harris, the lowest stratum found 
at Sisquoc is either wanting or of minor importance, and beds of dia¬ 
tomaceous shale lie conformably over the Monterey shale, making 
the dividing line very hard to find. West of Waldorf the contact 
is marked for miles by a bed of brecciated Monterey shale of coarse 
and fine fragments, in places cemented into a hard amalgam by a 
paste of bituminous material. Here the overlying beds are made 
up of fine shale and sand and pebbly sandstone, which, though actually 
separated by an important unconformity from the Monterey, as 
indicated by the brecciated zone and the abundance of pebbles of 
that formation in them, are conformable in dip with the underlying 
beds. A still younger series of fossiliferous shale and sand marks 
the base of the Fernando 14 miles northeast of Divide, and also north¬ 
east of Schumann and northwest of Mount Solomon; and on the 
summit of the ridge in the vicinity of the head of Pine Canyon, 
halfway between the two latter localities, the Monterey is capped 
by what appears to be a part of the same series somewhat younger 
still. This shows that at the locality near the head of Pine Can- 
yon either an overlap of the late Fernando occurred on an old 
eminence of Monterey shale that was above the sea at the time of 
the deposition of the part of the Fernando immediately preceding, 
causing the omission on its summit of hundreds of feet of sedi¬ 
ments which were deposited around its base; or else the portion 
of the Fernando preceding this series was removed from above the 
Monterey during a period of erosion within Fernando time, this 
period being followed by subsidence. 
Along the ridge 1 mile southeast of Redrock Mountain, in the 
Purisima Hills, there is a capping of diatomaceous shale resembling 
that of the Monterey in every respect, but containing characteristic 
Fernando fossils. It was not suspected that this shale belonged to 
a formation distinct from the Monterey until the fossils were found. 
