LOWER CRETACEOUS DEPOSITS CALIFORNIA AND OREGON

CRETACEOUS SEDIMENTARY DIVISIONS 55
From these records it appears that both Knoxville and lower Shasta
strata occur at intervals in the Diablo Range, chiefly on its eastern flank,
and that as far as is now known the two series are unconformably related.
Santa Lucia Range.—Sandstones and shales form a thick sequence of
strata along both flanks of the Santa Lucia Range and extend from Pine
Mountain southeastward into the San Luis quadrangle. The lower part
of the sequence found here contains a fauna typical of the Paskenta group.
Fairbanks (1895b) has described the beds occurring on the south slope
of Pine Mountain, referring to them as "Knoxville," but later study of the
fossils obtained there by Fairbanks and the writer (1S95) prove them to
be of Paskenta age. They include Aucella tra&m, A. injlata, and A. uncitoides,
and were found in calcareous concretionary layers in a dark clay
shale. From here the beds can be traced into the "Toro formation"
in the San Luis quadrangle of which they constitute the major part.
From the account of the "Toro formation" given by Fairbanks (1904), it
contains no strata older than the Paskenta. If Knoxville beds occur
about Pine Mountain or north ol San Luis Obispo, it seems probable that
they will be found to underly the Paskenta and to rest upon, or against,
the Franciscan (San Luis) formation. But no final account of these deposits
cart be made without the proper discrimination of these two series.
SaBarbara County,—In the region of complicated structures along
the upper branches of the Santa Ynez River, considerable areas of Mesozoic
sediment have been described by Kew (1919), and later by Nelson
(1925). In part these Mesozoic deposits are referable to the Knoxville
series, and in part to the Paskenta group of the Shasta series. Quoting
from tbe account given by Nelson, he writes:
"From tbe occurrence of both A ueella piachii and A ucelta, trajnticullit, it is Inferred
that the Knoxville as mapped, includes both the loner and upper divisions recognized
elsewhere in California ' 1
It appears from Nelson's account that tbe upper division of the so-called
"Knoxville" in this region is in fact the Paskenta group of the Shasta
series and that the lower division is properly referable to the Knoxville
series, as understood in this memoir,
OfiEOCN CHETACEOOS AREAS
General Statement,—The marine embayments in southwestern Oregon
in early Cretaceous time extended into tbe coastal valleys then existing
and also into tbe more inland valley of the Umpqua River (Dillard,
Myrtle Creek, and Riddle areas), and into the valley of the Illinois River.
Only in later epochs did it enter the central valley of the Rogue River,
farther to the east.
The Myrtle Formation.—The "Myrtle formation" was first described
by Diller (1898) as including tbe Cretaceous deposits along Myrtle Creek,