GEOLOGY AND PALEONTOLOGY OF PALOS - Pubs Warehouse

28 GEOLOGY AND PALEONTOLOGY OF PALOS VERDES HILLS, CALIFORNIA
Turritella ocoyana (pi. 28, figs. 1, 2), "Nassa" aff.
"N.'\ arnoldi, "Phos" dumbleanus (pi. 28, figs. 5, 6),
Cancellaria cf. C. condoni (pi. 28, fig. 8), Conus oweni-
anus (pi. 28, figs. 14, 15), and Aeguipecten andersonit
suggest the Temblor fauna as that term is generally
used. According to Kleinpell's interpretation of the
succession of foraminiferal zones, the fauna from the
Palos Verdes Hills is younger than the Barker's Ranch
fauna 52 in the Bakersfield region a fauna that has a
comparable proportion of small species and is considered
characteristic of the Temblor. Mollusks from the
Topanga formation in the Santa Monica Mountains M
and from strata assigned to the Temblor along the coast
southeast of the Palos Verdes Hills 54 consist principally
of large species. Foraminif era from the lower part of the
Topanga formation are assigned by Kleinpell to the
Siphogenerina branneri zone, which is identified in the
lower part of the Altamira shale. The upper part of the
Topanga formation may, however, include deposits of
the same age as the middle part of the Altamira. The
fauna of the Oursan sandstone and Hambre sandstone
of the Mpnterey group in the San Francisco Bay region
also consists principally of large species. 55 These sand­
stone formations in the Monterey group are referred by
Kleinpell to horizons higher than the middle part of the
Altamira shale.
Strombus and Divaricella are found in the Imperial
formation of the Colorado Desert. 56 The Imperial
fauna includes species that are more similar to Carib­
bean Miocene fossils than to fossil or riving species from
the Pacific coast. The following species from the
Palos Verdes Hills appear also to show that relation:
Strombus cf. S. gatunensis (pi. 28, figs. 3, 4), "Clavatula"
d."C." labiata (pi. 28, fig. 9), Terebra cf. T. lepta, Terebra
cf. T. wolfgangi, Macrocallista cf. M. maculata\(pl. 28, fig.
19), and Trigoniocardia aff. T. antillarum (pi. 28, figs. 24,
25). 57 The preservation of some of these species is so
poor, however, that their affinities are not certain.
The similarity between the Imperial fauna and the
fauna from the Palos Verdes Hills may have no age
significance, as it may be the result of derivation from
the same source. The Imperial formation isQconsidered
of Miocene age by some paleontologists and of Pliocene
age by others. 58
UPPER PART,
The upper part of the Altamira shale is characterized
generally by abundance of phosphatic shale, the phos­
phate material forming thin light-colored or brownish
layers or nodules. In many areas, particularly in the
western part of the hills, brown bituminous shale is in-
" The Barker's Eanch species have been described or recorded in the following
publications: Anderson, F. M., A stratigraphic study in the Mount Diablo Range of
California: California Acad. Sci. Proc., 3d ser., vol. 2, pp. 187-188, 195-206, pis. 14-16,
1905; The Neocene deposits of Kein River, Calif., and the Temblor Basin: Idem,
4th ser., vol. 3, pp. 99-100, 1911. Anderson, F. M., and Martin, Bruce, Neocene
record in the Temblor Basin, Calif., and Neocene deposits of the San Juan district,
San Luis Obispo County: Idem, 4th ser., vol. 4, pp. 41-44, 52-96, pis. 1-8,1914.
« Arnold, Ralph, New and characteristic species of fossil mollusks from the oil-
bearing Tertiary formations of southern California: TJ. S. Nat. Mus. Proc., vol. 32,
pp. 525-526, 528-534, pis. 40^6,1907. Arnold, Ralph, in Eldridge, Q. H., and Arnold,
Ralph, The Santa Clara Valley, Puente Hills, and Los Angeles oil districts, southern
California: U. S. Geol. Survey Bull. 309, pp. 147-148, pis. 27-33,1907. Kew, W. S. W.,
Geology and oil resources of a part of Los Angeles and Ventura Counties, Calif.:
U. S. Geol. Survey Bull. 753, pp. 50-51, 1924. Woodring, W. P., in Hoots, H. W.,
Geology of the eastern part of the Santa Monica Mountains, Los Angeles County,
Calif.; U. S. Geol. Survey Prof. Paper 165, pp. 100-101,1931.
«> Woodford, A. O., The San Onofre breccia: California Univ., Dept. Geol. Sci.,
Buil., vol. 15, p. 208, 1925.
" Merriam. J. C., in Lawson, A. C., U. S. Qeol. Survey Geol. Atlas, San Francisco
folio (No. 193), p. 11, 1914.
« Hanna, G. D., Paleontology of Coyote Mountain, Imperial County, Calif.:
California Acad. Sci. Proc., 4th ser., vol. 14, pp. 454-455, 464-465, pis. 20, 26, 1926.
" Macrocallista maculata has a range from Miocene to Recent in the Caribbean
region. Trigoniocardia antillarum is a Recent Caribbean species, the Caribbean
Miocene allies- of which have been overnamed.
M Woodring, W. P., Lower Pliocene mollusks and echinoids from the Los Angeles
Basin, Calif., and their inferred environment: U. S. Geol. Survey Prof. Paper 190,
pp. 46-47,1938.
terbedded with the phosphatic shale. Phosphatic
shale is a minor constituent of the middle part of the
Altamira, and the Valmonte diatomite member in­
cludes locally thin layers of phosphatic material.
In the western half of the hills the top of the upper
division of the Altamira corresponds approximately to
the transition from hard cherty to soft diatomaceous
rocks. On the northeast and east slopes the upper
division includes, however, diatomaceous strata that
contain blue-schist debris and that are interbedded with
fine-grained blue-schist sandstone and phosphatic
shale. In the Whites Point area cherty shale is more
abundant than elsewhere.
A peculiar litholpgic facies, consisting of thick blue-
schist conglomeratic sandstone and brecciated shale, is
represented in the Point Fermin area. In that area the
thickness and grain size of the sandstone decrease north­
ward. The thin layers of fine-grained blue-schist sand­
stone and the diatomaceous silt containing schist debris
farther north are thought to be the equivalent of the
coarse-grained sandstone of the Point Fermin area.
The schist debris was derived. evidently from a schist
area farther south, now covered by the ocean, as was
inferred for the San Onofre breccia, a Miocene formation
in the coastal district southeast of the Palos Verdes
Hills. 59
Natural exposures of the soft shale constituting a
large part of the upper division of the Altamira in most
areas are found only along the sea cliff and in some of
the deep canyons. The best exposures are in the
Lunada Bay and Malaga Cove areas, in the cliffs near
the head of Altamira Canyon and its tributaries, and at
Point Fermin. The thickness appears to be as much as
300 feet, possibly even as much as 400 feet, in the
Malaga Cove area and 250 feet in the Lunada Bay area.
In a tributary of the middle fork of Altamira Canyon
the thickness is 185 feet, and in the east fork of Altamira
Canyon, 1,500 feet to the southeast, it diminishes to 95
feet. In the Point Fermin area the thickness is at least
300 feet, and the top is not exposed. In that area,
however, sandstone forms two thick units.
Foraminifera assigned to the Bolivina, modeloensis
zone and the overlying Bulimina uvigerinaformis zone
were found in strata referred to the upper part of the
Altamira.
Strata assigned to the upper part of the Altamira
shale are exposed in the sea cliff southwest of the Malaga
Cove beach clubhouse, near the mouth of Malaga
Canyon. They consist of phosphatic shale with which
cherty shale and limestone are interbedded. The pro­
portion of cherty shale and limestone decreases upward
in the section. The lithology in this area is shown in
the following sections (column 1, pi. 3). The excep­
tionally great thickness suggests some duplication in the
two sections; however, the thickness is at least 270 feet
and may be as much as 400 feet, the combined thickness
of the two sections. If the opal concretions in the
underlying middle part of the Altamira are at the same
horizon as in the Altamira Canyon area (columns 2, 3,
pi. 3), the base .of the v upper part of the Altamira is
drawn at essentially the same horizon in the two areas.
" Woodford, A. O., The San Onofre breccia: California Univ., Dept. Geol. Sci.
Bull., vol. 15, p. 140, 1925.