LOWER CRETACEOUS DEPOSITS CALIFORNIA AND OREGON

CRETACEOUS SEDIMENTARY DIVISIONS 69
The chronological position of this zone is regarded as upper-middle
Albian, as judged by tbe presence in it of Beudanticeraa and Doumlleiceras,
aa well as the contents of the zones beneath it in ita type district and certain
fossils above it.
From tbe concretionary shale immediately beneath was obtained a
large example of PhyUoceras, of the group of P. veliedae Michelin. Of
tbe fourteen species named, eight have been found at Horsetown and
vicinity, and with tbem a few that seem to represent a somewhat higher
horizon, such as Beudantieeraa kaydeni (Gabb) and Nautilus charlottenms
Whiteaves. Both occur in the lowest beds exposed at Horsetown and
have also been collected with Pervinquieria inflata var. from transported
material at the mouth of Hulen Creek, a little above the horizon of the
Neptune zone.
The Packard zone, exposed on Alderson Creek 2 miles south of Ono,
appears to be a little higher in the section than the Neptune zone. Among
its representative fossils, a few were obtained also at Horsetown. The
list includes:
Oxytromdoceraa paekardi nov. Puzosia hoffmanni (Gabb)
DoutnUeiceTOs mammiUaiwm var. P, cf. planulata (Sowerby)
Btudaniicerat breweri (Gabb) P. alder»ona nov.
From the foregoing account of the successive zones in the Shasta series
in the Cottonwood district, it will be seen that they exhibit a faunal order
which ranges from the little-known Valanginian of the Paskenta group
through the several stages of the Horsetown (Hauterivian to Albian),
and ending only at the overlap of the Chico series, whose earliest beds
with Pervinquieria inflata var. Beudanticeras kaydeni (Gabb) and rudistid
species are of late Albian age.
It is not supposed that the faunas belonging to any of these zones are
completely known or that other zones of equal importance may not be
found later. It is hoped that enough is here given to indicate the stratigraphical
span of the Shasta series and to illustrate the faunal order of its
several zones as a basis for the general correlation of strata found in other
areas of the Great Valley, in neighboring troughs, and in more distant
areas on the Pacific Coast, or elsewhere. If better grouping of the faunas
may eventually be arranged, or the zones may be better illustrated or
named, the results will be welcomed by the writer as much as by others.
RESTWCTED HORSETOWN AREAS
General Statement.—The Horsetown group is most completely developed
on the western border of the Sacramento Valley, but beyond these limits
its distribution is small and its stratigraphic thickness much reduced.
Fossils representing only a small part of the group have been found in
other places, but its most representative faunas are lacking. In the