HomeMy WebLinkAboutSUP 07-03; South Coast Materials Quarry; Special Use Permit (SUP) (3)
PALEONTOLOGICAL MITIGATION REPORT
QUARRY CREEK
CITIES OF CARLSBAD & OCEANSIDE
SAN DIEGO COUNTY, CALIFORNIA
(W.O. No. 426485)
Prepared for:
Hanson Aggregates – Pacific Southwest, Inc.
9255 Camino Santa Fe
San Diego, CA 92121
Prepared by:
Department of PaleoServices
San Diego Natural History Museum
P.O. Box 121390
San Diego, California 92112
Thomas A. Deméré, Ph.D., Director
8 April 2013
Paleontological Resource Mitigation Final Report – Quarry Creek i
TABLE OF CONTENTS
TABLE OF CONTENTS ..................................................................................................................... i
PROJECT SUMMARY ...................................................................................................................... ii
INTRODUCTION .............................................................................................................................. 1
PROJECT DESCRIPTION ............................................................................................................. 1
DEFINITION AND SIGNIFICANCE OF PALEONTOLOGICAL RESOURCES ...................... 1
PERSONNEL ................................................................................................................................. 2
METHODS ......................................................................................................................................... 5
FIELD METHODS ......................................................................................................................... 5
Monitoring ................................................................................................................................. 5
Fossil Salvage ............................................................................................................................ 6
Stratigraphic Data Collection .................................................................................................... 6
LABORATORY METHODS ......................................................................................................... 6
Fossil Preparation ...................................................................................................................... 7
Curation ..................................................................................................................................... 7
RESULTS ........................................................................................................................................... 8
STRATIGRAPHY .......................................................................................................................... 8
Quaternary terrace deposits (Bay Point Formation) .................................................................. 8
Santiago Formation ................................................................................................................... 8
Peninsular Ranges Batholith ...................................................................................................... 9
PALEONTOLOGICAL COLLECTING LOCALITY ................................................................. 12
SDNHM Locality 6501 ........................................................................................................... 12
PALEONTOLOGY ...................................................................................................................... 12
Tracheophyta (vascular plants) ................................................................................................ 12
Icnofossils (tacks, trails, and burrows) .................................................................................... 12
DISCUSSION ................................................................................................................................... 14
INTRODUCTION ........................................................................................................................ 14
GEOLOGIC SETTING ................................................................................................................ 14
Bay Point Formation (Quaternary terrace deposits) ................................................................ 14
Santiago Formation ................................................................................................................. 15
PALEONTOLOGY ...................................................................................................................... 16
Previous Work ......................................................................................................................... 16
Quarry Creek Fossils ............................................................................................................... 17
Geologic Age ........................................................................................................................... 17
CONCLUSIONS AND SIGNIFICANCE ........................................................................................ 18
REFERENCES ................................................................................................................................. 19
APPENDIX ....................................................................................................................................... 20
Paleontological Resource Mitigation Final Report – Quarry Creek ii
PROJECT SUMMARY
This document presents the results of the paleontological resource mitigation program conducted
during mass grading activities for the Quarry Creek project. The project site is located along the
boundary between Carlsbad and Oceanside, California. Construction activities for this project
involved the reclamation of an old aggregate quarry site that occupied the area immediately
south of State Route 78 and Haymar Drive, and approximately 2,000 feet west of College
Boulevard and immediately west of the Khols and Walmart shopping centers. Work was
performed by staff members of the Department of PaleoServices (San Diego Natural History
Museum) for Hanson Aggregates Pacific Southwest, Inc. of San Diego, California.
The mitigation program included construction monitoring, fossil salvage, laboratory preparation
of salvaged specimens, curation of prepared specimens, and storage of curated specimens.
Excavation operations were monitored between August 25, 2011 and November 8, 2011.
Construction activities exposed sedimentary deposits of the Eocene-age Santiago Formation
(Member B) and unnamed Pleistocene-age Quaternary alluvium.
A single fossil collecting locality was discovered in the Santiago Formation during monitoring
and produced impressions of fragmentary plant material (leaves and parts of stems), as well as
trace fossils, primarily burrows. Although somewhat poorly preserved, these fossils do serve as
vouchers of the types of organisms preserved in the strata exposed by construction activities at
the project site. Further, these fossils have the potential to increase our understanding of the
paleontological history of southern California.
Paleontological Resource Mitigation Final Report – Quarry Creek 1
INTRODUCTION
PROJECT DESCRIPTION
This document presents the results of the paleontological resource mitigation program conducted
during mass grading activities for the Quarry Creek project. The project site is located along the
boundary between Carlsbad and Oceanside, California (Figures 1 and 2). Construction activities
for this project involved the reclamation of an old aggregate quarry site that occupied the area
immediately south of State Route 78 and Haymar Drive, and approximately 2,000 feet west of
College Boulevard and immediately west of the Khols and Walmart shopping centers.
Work was performed by staff members of the Department of PaleoServices (San Diego Natural
History Museum) for Hanson Aggregates Pacific Southwest, Inc. of San Diego, California. The
mitigation program included monitoring excavation activities, salvage of unearthed fossil
specimens, laboratory preparation of salvaged specimens, curation of prepared specimens, and
storage of curated specimens. Paleontological monitoring of excavation activities occurred
between August 25, 2011 and November 8, 2011, and took place wherever potentially
fossiliferous native sedimentary rocks were impacted by excavation operations.
The published geological map of Kennedy and Tan (2005) for the Oceanside-Carlsbad area
indicates that portions of the project site are underlain by sedimentary rocks of the Santiago
Formation; a rock unit that has produced significant fossils in the past. For this reason the
Santiago Formation is considered to have a high paleontological resource sensitivity wherever it
crops out (Deméré and Walsh, 1993). Given the scale and scope of the proposed project, it was
determined that construction activities had a strong potential to produce significant impacts to
paleontological resources.
DEFINITION AND SIGNIFICANCE OF PALEONTOLOGICAL RESOURCES
As defined here, paleontological resources (i.e., fossils) are the buried remains and/or traces of
prehistoric organisms (i.e., animals, plants, and microbes). Body fossils such as bones, teeth,
shells, leaves, and wood, as well as trace fossils such as tracks, trails, burrows, and footprints, are
found in the geological deposits (formations) within which they were originally buried. The
primary factor determining whether an object is a fossil or not, isn’t how the organic remain or
trace is preserved (e.g., “petrified”), but rather how old is the organic remain or trace. Although
typically it is assumed that fossils must be older than ~10,000 years (i.e., the widely accepted end
of the last glacial period of the Pleistocene Epoch), organic remains of early Holocene age can
also be considered to represent fossils because they are part of the record of past life.
Fossils are considered important scientific and educational resources because they serve as direct
and indirect evidence of prehistoric life and are used to understand the history of life on Earth,
the nature of past environments and climates, the membership and structure of ancient
ecosystems, and the pattern and process of organic evolution and extinction. In addition, fossils
are considered to be non-renewable resources because typically the organisms they represent no
longer exist. Thus, once destroyed, a particular fossil can never be replaced. And finally, for the
purposes of this report, paleontological resources can be thought of as including not only the
actual fossil remains and traces, but also the fossil collecting localities and the geological
formations containing those localities.
Paleontological Resource Mitigation Final Report – Quarry Creek 2
PERSONNEL
Dr. Thomas A. Deméré, Curator of Paleontology and Director of the Department of
PaleoServices at the San Diego Natural History Museum, served as Principal
Investigator/Qualified Paleontologist and report co-author. The paleontological field monitors
were Gino Calvano, Rodney M. Hubscher, Bradford O. Riney, and Shayne A. Boney.
Laboratory work, both fossil preparation and specimen curation, was carried out by Nicole
Anderson and Rodney M. Hubscher. The final mitigation report was prepared by Thomas A.
Deméré and Rodney M. Hubscher.
Paleontological Resource Mitigation Final Report – Quarry Creek 3
Figure 1. Index map of western San Diego County showing the general location of the Quarry Creek
project site (black circle).
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Figure 2. Map showing the general location of the Quany Creek project site (anow and recorded fossil
collecting locality 6501) south of State Route 78 in the cities of Carlsbad and Oceanside,
Califomia. Additional black circles with numerical labels indicate nearby recorded fossil
collecting localities not associated with the Quany Creek project.
Paleontological Resource Mitigation Final Report -Quany Creek 4
Paleontological Resource Mitigation Final Report – Quarry Creek 5
METHODS
FIELD METHODS
Field activities included monitoring of major excavation operations, examination of temporary
and permanent cut slopes, collection of unearthed fossil remains, and the recording of geologic,
stratigraphic, and taphonomic contextual data. Specific field methods and techniques are
discussed more fully below and were carried out in compliance with standard local and state
paleontological resource mitigation guidelines and the specific conditions of the project’s
mitigation monitoring and reporting program.
Monitoring
Excavation activities were monitored between August 25, 2011 and November 8, 2011. The
paleontological monitoring schedule was determined by conditions in the field. Monitoring
consisted of on-site inspections of areas of active excavations for unearthed fossil remains
(Figure 3). Ideally, inspections involved examination of every newly exposed surface, but
operationally this was often not possible. The pace and quantity of equipment in the cut
determined how often the monitor could make inspections. When the active excavations were
too dangerous to enter because of a narrow cut and/or heavy traffic, an elevated vantage point
provided a secure place from which to examine the progress of grading.
Figure 3. View looking northwest across Quarry Creek project site showing earthmoving operations.
Plutonic igneous rocks in foreground and layer sedimentary rocks (Santiago Formation) in
active cut slopes in background.
Paleontological Resource Mitigation Final Report – Quarry Creek 6
Safety procedures followed by field personnel included wearing appropriate clothing (high-
visibility vests, hard hats, and large hand-held orange flags), securing the attention of equipment
operators before entering an active cut, notifying grading personnel before beginning a salvage
excavation, and marking fossil discovery sites with surveyor's flagging. It is important to
emphasize that paleontological monitoring did not interfere with, nor delay, construction
operations.
Fossil Salvage
Fossil salvage methods employed at the Quarry Creek project site included hand-quarrying and
bulk matrix sampling and prospecting of spoils piles. The particular type of salvage procedure
employed depended on a number of factors, including: (1) importance, size, and number of
specimens at a given fossil discovery site; (2) how critical the area of discovery was to the
progress of the construction schedule; (3) the type of equipment being used in the vicinity of the
discovery site; and (4) the opinion of the construction superintendent and/or Resident Engineer.
The duration of individual salvage operations varied from minutes to hours to days. Most
salvage operations were of short duration (minutes), and employed “pluck-and-run” recovery
techniques. Others involved hand-quarrying fossils that were transported to the museum for
further preparation. The fossil-salvage techniques employed for this project are discussed in
greater detail below.
Hand-quarrying. Quarry-style salvages for paleontological projects are not of the conventional
type employed by archaeological investigations. Instead, they consist of site-specific “mining”
of fossil-rich sedimentary rock layers typically without the establishment of a reference
geographic grid system. Such quarry sites are worked by hand-picking through blocks of
exposed sedimentary matrix to discover partially exposed fossils (Figure 5). Fragile fossils are
stabilized using a chemical preservative or adhesive (usually Butvar, Vinac, and/or a
cyanoacrylate glue) prior to removal from the cut.
Stratigraphic Data Collection
Collection of stratigraphic data was an integral part of the monitoring operation. Outcrops
exposed in the active cut (Figure 6) and pre-shored side walls were examined and observed
geologic features were recorded on grading plans. The goals of this work were to delimit the
nature of fossiliferous sedimentary rock units in the project site, determine their geographical
distribution and depositional contacts, and record any evidence of structural deformation.
Standard geologic and stratigraphic data collected included lithologic descriptions (color, sorting,
texture, structures, and grain size), stratigraphic relationships (bedding type, thickness, and
contacts), and topographic position. Measurement of stratigraphic sections was done with a hand
level. Areas containing exposures of fossiliferous sedimentary rocks were studied in detail and
fossil localities were recorded on measured stratigraphic sections.
LABORATORY METHODS
Laboratory activities included mechanical preparation of fossil specimens, repair and
stabilization of broken/damaged specimens, specimen identification, specimen cataloging, and
specimen storage. Specific methods are discussed more fully below and were carried out in
Paleontological Resource Mitigation Final Report – Quarry Creek 7
compliance with the County of San Diego Guidelines for Determining Significance of
Paleontological Resources (Stephenson et al., 2007).
Fossil Preparation
Fossil specimens were prepared using standard mechanical fossil preparation techniques. When
possible, fossiliferous blocks were reduced as soon as possible to take advantage of the residual
sediment moisture in the sedimentary rock. As these blocks dried, they became more difficult to
prepare. The specimens were then mechanically cleaned of enclosing sedimentary matrix using
one or more of the following tools: X-acto knife, pin vise, pneumatic scribe, or air-abrasion unit.
Damaged specimens that required repair were glued back together using either cyanoacrylate
glues or carpenter’s white glue.
Curation
Fossil curation involved identification of individual fossil specimens, assignment of unique
specimen catalog numbers, entry of specimen catalog information into the SDNHM specimen
computer database, printing the specimen label, writing the catalog number on the specimen
using India ink on a patch of white acrylic paint, placement of the specimen with its label into
appropriate-sized paper specimen trays, and storage of the labeled specimen in the steel “Lane-
style” geological cabinets in the research collection area of the museum. A specimen number
can refer to a single isolated fossil if there is only one of that species recovered, or to numerous
fossils of the same species if there is an abundance of specimens of that species recovered. This
curation procedure was followed for all medium-sized specimens (1-20 cm in size), but was
modified for smaller and larger specimens.
Paleontological Resource Mitigation Final Report – Quarry Creek 8
RESULTS
The paleontological mitigation program conducted during construction activities at the Quarry
Creek project site resulted in the recovery of fossil remains from temporary exposures of the
non-marine Santiago Formation. The stratigraphy, paleontological collecting locality, and
paleontology resulting from the mitigation effort are discussed below.
STRATIGRAPHY
Grading operations at the Quarry Creek project site exposed approximately 40 vertical feet of
Cenozoic sedimentary rocks, including non-marine strata of the Eocene-age Santiago Formation
and non-marine, unnamed Pleistocene Quaternary terrace deposits. These sedimentary strata are
overlain in places by extensive deposits of artificial fill materials generated during prior mining
operations. In addition, the sedimentary strata are underlain by Mesozoic-age plutonic igneous
rocks of the Peninsular Ranges Batholith in the southern portion of the project site.
Quaternary terrace deposits (Bay Point Formation)
Approximately 25 feet of non-marine stratified Pleistocene river terrace deposits were exposed in
the northwestern portion of the project site. This Pleistocene sequence consisted of reddish
yellow, poorly sorted, coarse-grained, massive to cross-bedded, compact sandstones (Figure 4)
with local cobble concentrations of volcanic origin.
These Pleistocene-age strata occurred between approximately 105 and 127 feet above sea level
and, as exposed by grading operations, were seen to overlie an irregular erosional surface cut
into the underlying Santiago Formation. The relief on this erosion surface is due to Pleistocene
stream activity in the ancestral Buena Vista drainage system. After carving of the valley walls
the ancestral stream began depositing sediment until eventually the valley was “silted in.”
Although the Pleistocene strata on the project site primarily occurred as isolated, erosional
remnants, they are actually part of a more extensive sequence of Quaternary alluvial deposits that
is widespread to the west along the south side of State Route 78. These Quaternary alluvial
deposits are broadly correlative with strata mapped to the west as the Pleistocene-age Bay Point
Formation.
Santiago Formation
Approximately 40 feet of non-marine strata of the Eocene-age Santiago Formation were exposed
in the northern portion of the project site and consisted of a lower sequence of gray and purple
claystones and fine-grained sandstones overlain by an upper sequence of cream-colored, massive
silty sandstones and medium-grained sandstones (Figure 5). These strata were exposed between
105 and 143 feet in elevation (Figure 6).
An eroded cut slope along the northern boundary of the project site provided excellent exposures
of Santiago Formation strata and served as a useful reference section (Figure 7). This section
contained several layers of coarse-grained and pebbly sandstones and included both normally
graded strata as well as massive and well-laminated strata. Some contacts between beds were
gradational, while others were sharply erosional. A claystone stratum near the base of the
section contained a dense concentration of white caliche nodules that suggest ancient soil
formation processes.
Paleontological Resource Mitigation Final Report – Quarry Creek 9
Peninsular Ranges Batholith
The southern portion of the project site is underlain by crystalline basement rocks of the
Peninsular Ranges Batholith. These rocks consist of plutonic igneous rocks of tonalite
composition and represent the source of aggregate materials exploited by the previous mining
operations at the former quarry site. These plutonic rocks extend to an unknown depth and are
well exposed in the large cut slope that forms the southern boundary of the project site.
Figure 4. Horizontal cut surface produced by scrapers in the northwestern portion of the project site. The
cut surface exposes the depositional contact between light-colored, fine-grained Eocene-age
sandstones (Santiago Formation) on left and reddish-brown, coarse-grained Pleistocene-age
sandstones (Quaternary river terrace deposits) on right. Pencil at contact is 14 cm in length.
Paleontological Resource Mitigation Final Report – Quarry Creek 10
Figure 5. Composite stratigraphic section of the Santiago Formation as exposed during grading in the
northwestern portion of the Quarry Creek project site. Fossils were discovered and recovered
from SDSNH Locality 6501.
Paleontological Resource Mitigation Final Report – Quarry Creek 11
Figure 6. Finished cut slope in northern portion of project site exposing well stratified, non-marine
sedimentary rocks of the Eocene-age Santiago Formation.
Figure 7. Eroded cut slope in northwestern portion of project site showing well-exposed Eocene-age
strata of the Santiago Formation. Note, dark gray claystones and purple, fine-grained
sandstones and overlying cream-colored, massive sandstones.
Paleontological Resource Mitigation Final Report – Quarry Creek 12
PALEONTOLOGICAL COLLECTING LOCALITY
Monitoring of construction activities resulted in the discovery of one new paleontological
collecting locality at the Quarry Creek project site. The locality was discovered in sedimentary
rocks of the Santiago Formation. A formal description of this locality is included in the
Appendix, along with an annotated list of the recovered fossils.
SDNHM Locality 6501
Locality 6501 was discovered at an elevation of approximately 114 feet in strata of the Santiago
Formation as exposed along the north side of the project site. This locality represents two
discrete collecting sites which were collected three months apart. Fossils were recovered from a
two foot thick, yellowish gray mudstone stratum with grayish orange and pink mottling.
Underlying this stratum was a one foot thick, orange, oxidized, clast-supported, gravel
conglomerate with a fine-grained sandstone matrix. Directly overlying the fossil-producing
horizon was a seven foot thick, very light gray, poorly sorted, medium grained, massive, arkosic
sandstone interbedded with thin mudstone and siltstone laminations. These strata occurred near
the base of the Santiago Formation. Recovered fossils consist of fragmentary impressions of
land plants, as well as sediment-filled burrows. Locality 6501 has since been graded away.
PALEONTOLOGY
Fossil remains collected during the monitoring and salvage phases of the mitigation program
conducted for the Quarry Creek project were recovered from Eocene-age sedimentary deposits of
the Santiago Formation. The following paragraphs discuss these fossils within the context of
higher taxonomic groups (e.g. plants). The fossils were identified by Thomas A. Deméré and
Rodney M. Hubscher of SDNHM.
Tracheophyta (vascular plants)
A small, low diversity paleoflora was recovered from the Quarry Creek project site and consists
of partial leaves and stems of vascular plants that were washed into an Eocene freshwater stream
from surrounding riparian environments. Although the majority of the fossil plant material is
rather poorly preserved, there are some identifiable specimens including a partial leaf impression
from a plant close to Magnolia sp. (Figure 8).
Icnofossils (tacks, trails, and burrows)
Several well-preserved, sediment-filled burrows were collected from the Quarry Creek project
site. These trace fossils consist of horizontal branching burrows (Figure 9), as well as
cylindrical, vertical burrows and presumably represent traces made by burrowing organisms such
as annelid worms.
.·
..
Figure 8. Fossil leaf of plant close to Magnolia sp. discovered and recovered from Eocene-age strata of
the Santiago F01mation exposed during mass grading activities at the Quany Creek project site.
Scale bar equals 20 mm.
Figure 9. Trace fossil (branching, sediment-filled bun ow) discovered and recovered from Eocene-age
strata of the Santiago F01mation exposed during mass grading activities at the Quany Creek
project site. Scale bar equals 20 mm.
Paleontological Resource Mitigation Final Report -Quany Creek 13
Paleontological Resource Mitigation Final Report – Quarry Creek 14
DISCUSSION
INTRODUCTION
The following section is limited to a general discussion of the results of the paleontological
mitigation program conducted for the Quarry Creek project. Although academic research
questions dictated the field methods and types of data recorded, the overall goal of this
mitigation program was not to produce a research paper, but rather to salvage significant fossil
remains, record relevant stratigraphic and taphonomic data, and curate and permanently house
the salvaged fossil remains. The fossil assemblage of terrestrial plants and trace fossils
recovered from the project site are now in a condition for future scholarly research. The
important distinction is that the recovery and conservation of the fossils is a separate endeavor
from their scientific study.
GEOLOGIC SETTING
Along the coastal plain of San Diego County, basement rocks of the Jurassic-Cretaceous-age
Santiago Peak Volcanics and the Cretaceous-age Peninsular Ranges Batholith are
nonconformably overlain by sedimentary strata of late Cretaceous, Eocene, Oligocene, Miocene,
Pliocene, and/or Pleistocene age (Hanna, 1926; Kennedy, 1975; Kennedy and Moore, 1971;
Kennedy and Peterson, 1975; Walsh and Deméré, 1991). In the general vicinity of the Quarry
Creek project site, paleontologically sensitive sedimentary strata of the Eocene-age Santiago
Formation nonconformably overlie granitic rocks of the Cretaceous-age Peninsular Ranges
Batholith. The contact between the sedimentary and plutonic rock units is irregular, and
represents an early Eocene or Paleocene-age eroded surface or landscape that was rapidly buried
during middle Eocene time by a sequence of marine, lagoonal, and fluvial sedimentary rocks. On
the project site the Santiago Formation is unconformably overlain by non-marine Pleistocene-age
strata broadly correlative with the Bay Point Formation. More specific discussions of the
Pleistocene and Eocene sedimentary rocks are presented below.
Bay Point Formation (Quaternary terrace deposits)
Hertlein and Grant (1939) proposed the name Bay Point Formation to include both marine and
non-marine Pleistocene sedimentary rocks in the coastal San Diego area younger than the
Lindavista Formation. They chose the exposures at Bay Point (now called Crown Point) in
Mission Bay as their type locality and briefly described the stratigraphic section there as
consisting of “light gray cross-bedded sands [which] contain abundant specimens of Dendraster
and Donax.” They also assigned fossiliferous exposures at Pacific Beach, at the foot of 26th
Street (“Indian Point”), and at North Island (“Spanish Bight”) to their Bay Point Formation. It is
noteworthy that the authors had a very broad concept of their new stratigraphic unit describing it
in their columnar section as “1-30 feet; marine fossiliferous terrace deposits and non-marine
valley-fill, gravel, sand, and silt.” As such the Bay Point Formation was actually an all-inclusive
stratigraphic unit for all Pleistocene sedimentary deposits younger than the Lindavista
Formation.
Subsequent workers have applied the concept of the Bay Point Formation in a variety of ways.
Valentine (1959) and Kern (1971) lumped all of the younger marine Pleistocene deposits of San
Diego into their concept of the Bay Point Formation. Kennedy (1975) carried this “lumping”
even farther by including even non-marine slope wash in the Bay Point Formation. Emerson and
Paleontological Resource Mitigation Final Report – Quarry Creek 15
Chace (1959) adopted a more conservative approach to their concept of this rock unit, noting that
because of the “remnatal preservation” of the Pleistocene terraces in the San Diego area,
correlation of isolated outcrops could not be made with any certainty. Later, Kern (1977) and
Deméré (1981) called for the restricted use of the name Bay Point Formation to refer to deposits
only at the type locality. This usage was proposed in light of evidence based on amino-acid
racemization age estimates suggesting that several temporally distinct marine Pleistocene
deposits were then lumped under the concept of the Bay Point Formation. In addition, these
various deposits displayed stratigraphic and faunistic differences that seemed to warrant their
recognition as distinct units. However, given the fundamental requirement that formations be
mappable rock units, and the fact that middle and upper Pleistocene rock units in the San Diego
region have very discontinuous areas of outcrop, it is more practical to return to the original
definition of Hertlein and Grant (1939) and recognize an inclusive Bay Point Formation. If
necessary, this more inclusive lithostratigraphic unit could be subdivided into local facies or
informal members. Most recently, Kennedy and Tan (2005) have utilized this approach to map
middle and upper Pleistocene marine, paralic, and non-marine deposits in coastal San Diego
County. Unfortunately, these authors have also chosen to entirely abandon use of the name ‘Bay
Point Formation’ in favor of an informal stratigraphic nomenclature that relies on topographic
position in relationship to individual elevated marine abrasion platforms (e.g., Unit 6, Old paralic
deposit resting on the 22-23 m Nestor terrace). The Pleistocene sedimentary rocks exposed at
the Quarry Creek project site are non-marine fluvial and floodplain deposits associated with a
river or stream system that existed in middle and late Pleistocene time during interglacial periods
of global warming. Although these Pleistocene deposits are typically mapped in the Carlsbad
and Oceanside region as unnamed older alluvium or Quaternary terrace materials, they are
broadly correlative with coeval deposits mapped near San Diego as the Bay Point Formation.
Santiago Formation
Woodring and Popenoe (1945) proposed the name “Santiago Formation” to refer to the Eocene-
age sequence of fossiliferous marine siltstone and sandstone beds that crop out in the Santa Ana
Mountains in Orange County, California. Wilson (1972) detailed lithostratigraphic and
biostratigraphic similarities between the Santiago Formation in Orange County, and a sequence
of Eocene marine and non-marine strata that crop out throughout the northwestern portion of San
Diego County. Based on these similarities, Wilson (1972) assigned the strata in the Oceanside
and Carlsbad areas to the Santiago Formation. Wilson (1972) also subdivided the formation into
three informal members: (1) a basal marine member (“Member A”) composed predominantly of
green mudstone and sandy mudstone interbedded with blue, tuffaceous sandstone and lenticular,
concretionary sandstone; (2) a middle marine member (“Member B”) composed predominantly
of very fine- to medium-grained, moderately well-cemented, arkosic sandstone; and (3) a non-
marine upper member (“Member C”) composed of fine- to very coarse-grained, light gray to
white, friable, cross-bedded, arkosic sandstone that contains interbeds of greenish-brown
siltstone, silty mudstone, claystone, and scattered pebble and cobble conglomerate. The Eocene-
aged sedimentary deposits exposed in the Quarry Creek project area have been assigned to
member “B” of the Santiago Formation by museum personnel. Sedimentary deposits of the
Santiago Formation exposed on other project sites in the vicinity of the Quarry Creek project
area and elsewhere in northern San Diego County have yielded numerous specimens of fossil
land mammals that are characteristic of the early and late Uintan Land Mammal Age (Walsh,
1996).
Paleontological Resource Mitigation Final Report – Quarry Creek 16
PALEONTOLOGY
Previous Work
Pleistocene: Valentine (1961), Kern (1977), Deméré (1980), and Kern and Rockwell (1992)
have provided summaries of previous paleontological work on the Pleistocene rocks of coastal
San Diego County. These studies have focused on diverse and well-preserved nearshore marine
invertebrate assemblages collected from locally well-exposed marine terrace and estuary/bay
deposits. The age, geologic setting, and sedimentology of the Pleistocene terrace deposits have
been studied by several authors (Eisenberg 1985; Kern and Rockwell 1992). In 1994 excavation
operations for the Town Center North shopping center at College Boulevard and State Route 76
in Oceanside resulted in the discovery and recovery of significant fossil remains of freshwater
fishes, aquatic birds, capybara, tapir, horse, and mastodon from a transgressive sequence of
Pleistocene fluvial and lacustrine deposits similar to those exposed at the Quarry Creek project
site. In 2000 excavation operations for the Terraces at Sunny Creek residential project in eastern
Carlsbad resulted in the discovery of fossil remains of Pleistocene land mammals including horse
and mammoth. The next year, excavation operations for the Ocean Ranch Commercial Center
located on Oceanside Boulevard resulted in the discovery and recovery of fossil remains of
horse, camel, and bison from Pleistocene fluvial deposits probably correlative to those exposed
at the Quarry Creek project site. In 2002 excavation activities for the Wanis View Estates
project in the San Luis Rey River Valley resulted in the recovery of a diverse assemblage of
Pleistocene land mammals that included partial skeletons of tapirs, mastodons, and mammoths.
In 2004 construction of the Summit at Carlsbad project near El Camino Real unearthed remains
of horse, camel, deer, and bison. And finally in 2007 and 2008 excavations at the Robertson
Ranch project site along College Boulevard in northern Carlsbad resulted in the discovery of
isolated bones and partial skeletons of rodents, rabbits, tapir, horse, camel, deer, mastodon, and
ground sloth. Together, these records of Pleistocene terrestrial vertebrates from Oceanside and
Carlsbad represent the most extensive occurrences of “Ice Age” land mammal fossils in coastal
San Diego County.
Eocene: Member “B” of the Santiago Formation has produced well-preserved fossils from
many localities in northern San Diego County (Deméré and Walsh, 1993). These fossils include
the remains of both terrestrial and aquatic animals and terrestrial plants. Terrestrial mammals
include the remains of opossums, insectivores, primates, rodents, brontothere, rhinoceros, and
uintathere. Also known are reptiles including turtle and crocodile, cartilaginous fish including
shark and ray, bony fish including catfish and herring, and a high diversity of marine and
estuarine fossil invertebrates including crustaceans, gastropods, and bivalves. Plant fossils
include the remains of palm, mangrove, willow, cocoplum, and almond tree (unpublished
SDSNH paleontological data).
Fossil invertebrates known to occur in strata of member “C” of the Santiago Formation include
inarticulate brachiopods, barnacles, ostracods, crabs, echinoderms, and a diverse molluscan
fauna that includes scaphopods, roughly 15 genera of gastropods, and 30 genera of pelecypods.
Fossils of marine vertebrates recovered from member “C” include teeth of cartilaginous fish
(sharks, skates, and rays) and teeth and otoliths of bony fish (unpublished SDSNH
paleontological data). Terrestrial vertebrates including fossil reptiles, birds, and mammals have
also been recovered from the near shore marine facies of member “C” of the Santiago Formation.
The fossil reptile fauna includes specimens of lizards, snakes, tortoises, soft-shelled turtles, and
crocodiles. The fossil mammal fauna includes artiodactyls such as Leptoreodon, Protylopus, and
Paleontological Resource Mitigation Final Report – Quarry Creek 17
Protoreodon; perissodactyls such as the rhinoceros Amynodon sp., the tapir Dilophodon sp., and
the brontotheres Parvicornis occidentalis and Metarhinus sp.; carnivorous mammals include the
creodonts Apataelurus sp., Limnocyon sp., and Hyaenodon sp., and the miacids (eucarnivores)
Miacis sp., Miocyon sp., Plesiomiacis sp., Procynodictis sp. Small mammals (represented by
fragmentary jaws and isolated teeth), such as bats, insectivores, and rodents have also been
recovered from this unit (unpublished SDSNH paleontological data). The Santiago Formation
was assigned a high paleontological resource sensitivity ranking by Deméré and Walsh (1993).
Quarry Creek Fossils
Eocene: The Eocene plant fossils recovered from member “B” of the Santiago Formation as
exposed at the Quarry Creek project site provide a glimpse of the subtropical riparian flora that
lived along local, coastal streams during the middle part of the Eocene Epoch. More diverse
fossil floras recovered from other sites in the Carlsbad-Oceanside area reveal a variety of Eocene
plant communities that once flourished here including lush tropical hardwood forests and dense
stands of mangroves.
Geologic Age
Pleistocene: The absolute age of the Pleistocene non-marine sandstones exposed at the Quarry
Creek project site is imprecisely known. The topographic position of the Pleistocene units well
above current sea level suggests deposition during an interglacial period. This could equate with
oxygen isotope stage (OIS) 5e (Sangamon) or OIS 7 (Yarmouthian) and older. Pending more
detailed stratigraphic and geochronologic investigations it is here suggested that the age range
for the Pleistocene deposits at Quarry Creek are either 120,000 or 200,000 years old.
Eocene: The absolute age of the Eocene marine sandstones and siltstones exposed at the Quarry
Creek project site also is imprecisely known. However, based on diverse molluscan assemblages
collected elsewhere from member “B” and on correlative estuarine and fluvial strata containing
land mammal fossils, it is suggested that the Eocene marine claystones and sandstones at the
Quarry Creek project site are approximately 42 million years old.
Paleontological Resource Mitigation Final Report – Quarry Creek 18
CONCLUSIONS AND SIGNIFICANCE
The paleontological resource mitigation program conducted during construction of the Quarry
Creek project reduced adverse impacts of on-site grading to paleontological resources to a level
below significance through construction monitoring, fossil salvage, fossil preparation, and fossil
curation. This work resulted in the recovery of paleontological resources from a single fossil
collecting locality discovered in sedimentary rocks of the Eocene-age Santiago Formation. This
locality was discovered as a direct result of monitoring of excavation activities.
The recovered Eocene fossil assemblage consists of impressions of fragmentary plant material
(leaves and parts of stems), as well as trace fossils, primarily burrows. Although somewhat
poorly preserved, these fossils do serve as vouchers of the types of organisms preserved in the
strata exposed by construction activities at the project site. Further, these fossils have the
potential to increase our understanding of the paleontological history of southern California.
Paleontological Resource Mitigation Final Report – Quarry Creek 19
REFERENCES
Deméré, T. A. 1980. A late Pleistocene molluscan fauna from San Dieguito Valley, San Diego
County, California. San Diego Society of Natural History Transactions 19:217-226.
Deméré, T.A. 1981. A newly recognized late Pleistocene marine fauna from the City of San
Diego, San Diego County, California. In, P.L. Abbott and S.O'Dunn (eds.), Geologic
Investigations of the San Diego Coastal Plain. San Diego Association of Geologists,
fieldtrip guidebook, pp. 1-10.
Deméré, T. A. and S. L. Walsh, 1993. Paleontological Resources, County of San Diego.
Unpublished report prepared for the Department of Public Works, County of San Diego:
1-68.
Eisenberg, L.I. 1985. Pleistocene faults and marine terraces, northern San Diego County. Pp. 87-
91. In P.L. Abbott (ed.). On the Manner of Deposition of the Eocene Strata in Northern
San Diego County. San Diego Association of Geologists, fieldtrip guidebook, pp. 87-91.
Emerson, W.K., and E.P. Chace. 1959. Pleistocene mollusks from Tecolote Creek, San Diego,
California. San Diego Society of Natural History, Transactions 12:335-345.
Hanna, M. A. 1926. Geology of the La Jolla Quadrangle, California. University of California
Publications in Geological Sciences 16: 187-246.
Hanna, M.A. 1927. An Eocene invertebrate fauna from the La Jolla quadrangle, California.
University of California Publications in Geological Sciences, 16:247-398.
Hertlein, L.G., and U.S. Grant, IV. 1939. Geology and oil possibilities of southwestern San
Diego County. California Journal of Mines and Geology 35:57-78.
Kennedy, M. P. 1975. Geology of the San Diego metropolitan area, California. Section A -
Western San Diego metropolitan area. California Division of Mines and Geology,
Bulletin 200: 9-39.
Kennedy, M. P. and G. W. Moore. 1971. Stratigraphic relations of upper Cretaceous and Eocene
formations, San Diego coastal area, California. American Association of Petroleum
Geologists, Bulletin 55: 709-722.
Kennedy, M. P., and G. L. Peterson. 1975. Geology of the San Diego metropolitan area,
California. Section B - Eastern San Diego metropolitan area. California Division of
Mines and Geology, Bulletin 200: 42-56.
Kennedy, M. P., and S. S. Tan. 2005. Geologic map of the Oceanside 30’ X 60’ Quadrangle,
California. California Geological Survey, Digital Database
(ftp://ftp.consrv.ca.gov/pub/dmg/rgmp/Prelim_geo_pdf/oceanside_map2_ai9.pdf).
Kern, J.P. 1971. Paleoenvironmental analysis of a late Pleistocene estuary in southern California.
Journal of Paleontology 45:810-823.
Kern, J.P. 1977. Origin and history of upper Pleistocene marine terraces, San Diego, California.
Geological Society of America Bulletin 88:1553-1566.
Kern, J.P. and T.K. Rockwell. 1992. Chronology and deformation of Quaternary marine
shorelines, San Diego County, California. Pp. 377-382 In C.H. Fletcher, III and J.F.
Paleontological Resource Mitigation Final Report – Quarry Creek 20
Wehmiller (eds.). Quaternary Coasts of the United States: Marine and Lacustrine
Systems, SEPM Special Publication 48.
Stephenson, B., and others. 2007. County of San Diego Guidelines for determining significance,
paleontological resources. Land Use and Environment Group, Department of Planning
and Land Use, Department of Public Works, 46 p.
Valentine, J.W. 1959. Pleistocene molluscan notes. I. The Bay Point Formation at its type
locality. Journal of Paleontology 33:685-688.
Valentine, J.W. 1961. Paleoecologic molluscan geography of the California Pleistocene.
University of California Publications in Geological Sciences 34:309-442.
Walsh, S. L., 1996. Middle Eocene mammal faunas of San Diego County, California; pp. 75-
119. In, D. R. Prothero and R. J. Emry (eds.). The Terrestrial Eocene-Oligocene
Transition in North America. Cambridge University Press, Cambridge England.
Walsh, S. L., and T. A. Deméré. 1991. Age and stratigraphy of the Sweetwater and Otay
formations, San Diego County, CA; pp. 131-148. In, P. L. Abbott and J. A. May (eds.).
Eocene Geologic History San Diego Region. Society of Economic Mineralogists and
Paleontologists, Pacific Section 68.
Wilson, K. L. 1972. Eocene and related geology of a portion of the San Luis Rey and Encinitas
quadrangles, San Diego County, California. Unpublished Master of Science Thesis,
University of California, Riverside.
Woodring, W. P., and W. P. Popenoe. 1945. Paleocene and Eocene stratigraphy of northwestern
Santa Ana Mountians, Orange County, California. United States Geological Survey Oil
and Gas Investigations Preliminary Chart 12.
Paleontological Resource Mitigation Final Report – Quarry Creek 21
APPENDIX
DATE 04/08/13
TIME 15:26:54
LOCALITY # LOCALITY NAME
6501 Quarry Creek 2011
LOCATION
COUNTRY USA
STATE CA
COUNTY San Diego
CITY Carlsbad
SECT TWNSP DIREC RANGE DIR
LOCATION IN SECTION
ELEVATION
LITHOLOGY
mdst
CITATION
DONATED BY
114 FT
DEPOSITIONAL ENVIRONMENT
marine deltaic
Hanson Aggregates 12 Sep 2011
LOCALITY DESCRIPTION
SAN DIEGO NATURAL HISTORY MUSEUM
DEPARTMENT OF PALEONTOLOGY
LOCAL! TY CARD
FIELD NUMBER
see below
LATITUDE 33°10'5111N VARIANCE
LONGITUDE 117°18'1111W
UTM 11 471841 3671166 VARIANCE
MAP NAME San Luis Rey, CA
MAP SCALE 1:2400D DATUM NAD1927
MAP SOURCE USGS 1968(1975)
FIELD NOTES
RMH#1 pg.87,133
COLLECTOR
R.M. Hubscher 12 Sep 2011
COMPILED BY
R.M. Hubscher 0 Mar 2013
STRATIGRAPHIC POSITION
GROUP
lOCAliTY#-6501
FORMATION Santiago Formation
MEMBER
INFORMAL NAME member B
ERA Cenozoic
SYSTEM Paleogene
SER/EPOCH middle Eocene
AGE/STAGE
NALMA
ZONE NAME
PHOTOS ACCESS NO.
y
ENTERED BY
R.M. Hubscher 5 Apr 2013
This locality was discovered during paleontological monitoring of excavation operations for the Quarry Creek 2011 project, Located along the boundary
between Carlsbad and Oceanside, California. Construction activities for this project involved the reclamation of an old aggregate quarry site that
occupied the area immediately south of State Route78 and Hayrnar Drive, and approximately 2,000 feet west of College Boulevard and immediately west of the
Khols and Yalmart shopping centers. Locality 6501 represents two field numbers collected within 20 horizontal feet of each other. Locality 6501 occurred
at an elevation of 114 to 115 feet and was discovered near the base of an approximately 30 foot cut slope situated in the northwest corner of the project
site.
Fossils were collected from a 2 foot thick mudstone interval within the middle Eocene, Santiago Formation (informal Member B). The b~ from which the
fossils were collected was a yellowish gray mudstone with grayish orange pink coloration intermittently throughout. Discovered fossils from this horizon
were confined to the immediate area of the two field numbers and not observed elsewhere along strike in the same horizon. Underlying Locality 6501 was a
one foot thick, orange, oxidized, clast-supported, moderately rounded gravel conglomerate with a fine-grained sandstone matrix. Directly overlying
Locality 6501 was a 7 foot thick, very Light gray, poorly sorted, medium grained, massive, arkosic sandstone interbedded with thin (<1/2 inch) mudstone and
siltstone laminations. These strata occurred near the base of the Santiago Formation, which as exposed on the project site cropped out between 105 and 143
feet in elevation. An eroded cut slope along the northern boundary of the project site provided excellent exposures of Santiago Formation strata and
served as a useful reference section. This section consisted of a tower sequence of gray and purple claystones and fine-grained sandstones overlain by an
upper sequence of cream-colored, massive silty sandstones and medium-grained sandstones.
Fossils were recovered by had quarrying blocks of claystone matrix from the temporary cut slope and splitting the blocks. Recovered fossils consist of
poorly-preserved and fragmentary impressions of land plants. As recovered were various kinds of trace fossils, primarily burrows.
The fossiliferous bed from which this locality was collected has been graded away and is no longer accessible.
Field Numbers: RHM12Sep11-1; RHM5Nov11-1
Collecting Dates: 12 September 2011; 5 November 2011
Elevation Range: 114-122
LOCALITY 6501
DATE D4/08/13
TIME 15:26:31
SPECIMEN NUMBER OF
NUMBER ITEMS
135095
135096
135097
135098
135099
135100 1
135101 2
135102 1
135103 2
135104 2
135105 2
135106
135107
DESCRIPTION
burrow on matrix
burrow in matrix
burrows in matrix
branching burrow on matrix
burrow free of matrix, back filled
impression of partial leaf; burrow
impression of possible flower bud
impression of possible leaf on matrix
impression of possible stem or leaf
impression of possible stem
impression of woody material
impression of plant material
impression of plant material
SAN DIEGO NATURAL HISTORY MUSEUM
DEPARTMENT OF PALEONTOLOGY
FAUNAL LIST FOR LOCALITY 6501
Quarry Creek 2011
SPECIES
Ichnofossil
Ichnofossi l
Ichnofossi l
Ichnofossil
Ichnofossi l
cf. Magnolia sp.
Dicotyledonae
Dicotyledonae
Tracheophyta
Tracheophyta
Tracheophyta
Tracheophyta
Tracheophyta
PAGE
PAL270