LOWER CRETACEOUS DEPOSITS CALIFORNIA AND OREGON

80 3WJWEH CRETACEOUS DEPOSITS IN CALIFORNIA AND OREGON
the Shasta series. Among cepholopods the Antillean Lower Cretaceous
contains few, if any, of the large lytoceratids, crioceratids, ancyloceratids
(Tropaeum, Shastoceras, and Hemibaculites), or phylloceratids, such as
characterize the Horsetown group of the Shasta series* Contrasts of
this character could easily be further extended, continuing through the
Lower Cretaceous in the two provinces, but they seem unnecessary at
present.
These contrasts seem to 9how little, if any, faunal exchange between
the Atlantic and Pacific provinces in early or Middle Cretaceous tune
Any resemblances that exist between them can be more easily accountcd
for in some other way,
Argentina and Chile.—The faunal contrasts, long known in the Shasta
and Comanche series of North America, reflect the distinctness of the
Indo-Pacific from the Tethyan-Atlantic provinces during late Mesozoic
periods. No such contrasts have been pointed out between the faunas of
the Shasta series and those in the Lower Cretaceous of Chile and western
Argentina. Both are regarded as having Indo-Pacific relations which
ally them to some extent at least. Kitchin (1926) traces faunal relationships
from Argentina eastward to the Indo-Pacific basin, but without
referring to the important West Coast faunas represented in tbe Shasta
series and in contemporary deposits farther north—partly for the reason
that they have not been known. He says, in part:
"The deposits of Lower CretaceouB see i.11 Bolivia, Chile, and Argentina republic,
aa well known, have paleontologicaj characteristics in common with the Lower
Cretaceous beds of South African and Tanganyika Territory. Related faunas of
like age are also present in Madagascar, in Cutch, near Coconada (east coast of
India), in Hazara (western Himalaya), and in New Caledonia."
Had Kitchin known the American West Coast faunas, as here illustrated,
be could have continued these analogies farther eastward.
European Sections.—When the sedimentary succession of the Shasta
series in California and Oregon is compared with those of Europe for
purposes of correlation their great stratigraphical and lithological contrasts
at once appear. The total thickness of contemporary deposits
in western Europe and England is estimated at less than one-fifth of that
found in California, so that their respective subdivisions cannot easily be
compared. In some measure the same statement applies also to Oregon
and to other parts of the Pacific Coast. According to estimates gathered
from authentic sources (Geikie, 1893) the Cretaceous system in England
attains a maximum thickness of less than 4200 feet, nearly half of which
represents the Wealden, largely included in the Infra-Valanginian. Overlying
this in southeastern England are sediments of Neocomian to Senonian
ages, inclusive, having a thickness of 2128 feet. Neither these aggregates,
their subdivisions, chronological units, nor the stratigraphic ratios
of the latter compare well with those of the California sections. As the