HomeMy WebLinkAboutPaleontological Assessment
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PALEONTOLOGICAL RESOURCES ASSESSMENT
CAMPOS VERDES PROJECT,
RANCHO CALIFORNIA, CALIFORNIA
PREPARED FOR:
MR. DOUG WOOD
WOOD AND ASSOCIATES
1000 QUAIL, SUITE 165
NEWPORT BEACH, CALIFORNIA 92660
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PREPARED BY:
DR. FRANCES M. GOVEAN
RMW PALEO ASSOCIATES
23352 MADERO, SUITE J
MISSION VIEJO, CALIFORNIA 92691
19 OCTOBER, 1989
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O INTRODUCTION
The following report presents the results of RMW's assessment of
the paleontological resources of the Campos Verdes site, Rancho
California, California.
The study site is an irregularly shaped parcel of approximately
131 acres located northeast of Interstate 15 and southeast of
Banana Avenue (Winchester Road) on the southeast (Figure 1).
The purpose of the following report is to assess the known and
potential paleontological resources within the study area. This
study is based on a review of published pertinent paleontological
and geological literature and the locality records of the Natural
History Museum of Los Angeles County and the San Bernardino
County Museum. Dr. J. D. Stewart of the Los Angeles County
n Museum and Mr. Robert Reynolds of the San Bernardino County
~•J Museum were contacted concerning any known fossil localities both
within the site and in the general vicinity. Mr. Dave Stevens,
Ms. Marilyn Morgan and Ms. Diana Weir conducted a walkover survey
of the site on November 3, 1988. No fossils were located during
the survey.
STRATIGRAPHY AND PALEONTOLOGY
The study area is primarily with exposures of the Pauba Formation
and recent alluvium. The Pauba is exposed mainly along stream
channels and gullies. The Pauba Formation is Pleistocene (10,000
to 1.8 million years) and was deposited in ancient streams that
flowed across the landscape during the last "Ice Age." Recent
grading monitoring has produced large numbers of fossil
vertebrate animals from this formation within the Rancho
California and Murrieta area. Fossil camel, horse, antelope,
O bison and elephant have been excavated and archived at the Los
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Angeles County Museum. Several specimens, including one
tentatively identified as a carnivore, are awaiting study and
O should expand this fossil list considerably. The earliest
recorded fossils were a tapir and a horse exposed northeast of
the Ynez Road and Winchester Road intersections (Mann, 1955,
Raschke, 1988). A fossil horse skull was excavated on P.M.
19677, next to the study area (Raschke 1988). Mr. Robert
Reynolds, San Bernardino County Museum, reported that over 75
different taxa have been collected from the Pauba Formation and
the "unnamed sandstone" unit within the Winchester Hills area.
The collection at San Bernardino County Museum contains fossils
that vary in size from small rodents to large grazing animals.
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The recent alluvial deposits are sediments laid down by streams
that flowed across the region within the last 10,000 years.
These sediments are considered to be too young geologically to
contain any significant fossils.
The Pauba Formation has contained large numbers of significant
vertebrate fossils within the area of Rancho California,
Murrieta, and the Winchester Hills. Their large numbers and
diversity suggests that they will be of great importance in our
understanding of the Pleistocene paleontology of southern
California and possibly even North America (Raschke 1988).
Raschke (1988) postulates that this area of southern California
may have been a mayor migration pathway for land animals between
North and South America during the Pleistocene. Continued
expansion of the fossil collection from the Pauba Formation could
shed additional light on both the populations and migrations of
animals in the Pleistocene.
CONCLUSIONS
At the end of the Pleistocene, nearly 32% of-the larger land
animals became extinct. As the Pauba Formation was being
O deposited during this time, studies of the fossil vertebrates may
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provide valuable additional information on this maJor extinction
event.
The paleontologic sensitivity of a rock unit is determined by its O
past history of fossil discovery. This sensitivity is a measure
of the potential for the discovery of paleontological resources
during earthmoving activities. Grading and other developmental
activities can expose fossils, but by the same token, can destroy
these same remains. This would have a significant adverse impact
on the paleontological resources of the region. However, proper
mitigation measures can reduce these adverse impacts to
acceptable levels.
Considering its past history of fossil discovery, the Pauba
Formation is considered to have a Moderate to High
paleontological sensitivity. The recent alluvium is considered
to have a LOW paleontologic sensitivity. However the recent
alluvium could be a thin veneer and grading could expose the
underlying Pauba Formation. Proper mitigation measures are
required to reduce the adverse impact of development and protect O
the paleontological resources of the study area.
MITIGATION MEASURES
The following measures are required. to reduce the adverse impacts
of development to an acceptable level and to protect the fossil
resources of the site. These mitigation measures are drawn from
past efforts and have proven successful in protecting
paleontological resources, while allowing the timely completion
of developments in Rancho California and elsewhere in southern
California.
1. A qualified paleontologist shall be retained to perform
inspections of the site and to salvage exposed fossils.
The frequency of these inspections will depend on the
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frequency of the discovery of fossils and the rate of
excavation.
O 2. The paleontologist shall be allowed to divert or direct
grading in the area of an exposed fossil in order to
facilitate evaluation and, if necessary, salvage.
3. Due to the small nature of some of the fossils present
it may be necessary to collect matrix samples for
processing through fine screens.
Fences M. Govean, Ph.D.
Paleontologist
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REFERENCES AND PERSON CONTACTS O
Dr. J.D. Stewart, Natural History Museum of Los Angeles. (213)
744-3318.
Mr. Robert Reynolds, San Bernardino County Museum. (714)
825-4825.
Mann, J.F., Jr., 1955. Geology of a portion of the Elsinore
Fault Zone California: Calif. Div. Mines Special Report 43,
22 PP•
Morgan, Marilyn, 1988. Paleontological Report Fossil Vertebrate
Localities in the Pauba Formation, Rancho California,
Riverside County, California, Tracts 20735-7-8-9 & 20881.
Prepared for Warmington Homes. Ms. on file at RMW Paleo
Associates, Mission Viejo, CA.
Morgan, Marilyn, 1988. Paleontological Report. Tracts 21672 and
21673 Rancho California, Riverside County, California.
Prepared for Mesa Homes. Ms, on file at RMW Paleo
Associates, Mission Viejo, CA.
Raschke, R., 1986. Final Report on the Results of
Paleontological Monitoring Efforts at Corporate Park V.,
P.M. 19677, Rancho California: Prepared for Kaiser /'~
Development Company, 4 pp. Ms. on file at RMW Paleo v
Associates, Misaion Viejo, CA.
Raschke, R., 1987. Final Report on Paleontological Resources
Monitoring at Margarita Village, Tracts 20735-1,-2, -3, -4,
-5, -6 and 21802, 21082-2, -3, -4 Rancho California,.
California: Prepared for Kaiser Development Company, 5 pp.
Ms. on file at RMW Paleo Associates, Mission Viejo, CA.
Raschke, R., 1988. Assessment of the Paleontological Resources
within Tentative Parcel Map 23336, Winchester Hills, Rancho
California, California, 4 pp. Ms. on file at RMW Paleo
Associates, Mission Viejo, CA .'
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