HomeMy WebLinkAboutCT 98-05; De Jong Property; Tentative Map (CT) (8)I
I
PALEONTOLOGICAL RESOURCE ASSESSMENT,
•
MORNING RIDGE PROJECT, DE JONG PROPERTY,
CITY OF CARLSBAD, SAN DIEGO COUNTY, CALIFORNIA
• (CT 98-05)
I
For:
I
I
Keystone Communities
1 5333 Mission Center Road, Suite 360
San Diego, California 92108
I
I
- By:
I
•
Brian F. Smith and Associates
Archaeological, Historical, and Paleontological Consulting
14678 Ibex Court, San Diego, California 92129
I
I
I 8 April 2003
I
I
I
i
i
I
i
i
i
i
i
i
i
i
i
i
i
i
i
i
i
Paleontological Monitoring for the Morning Ridge Project
INTRODUCTION
The California Environmental Quality Act (CEQA) requires local governmental
agencies to consider potential impacts to paleontological resources and mandates that
mitigation measures be implemented when these resources are likely to be threatened by
construction related activities. In the City of Carlsbad, the Planning Department,
pursuant to CEQA regulations for excavation and/or construction activities, requires a
mitigation, monitoring, and reporting program be instituted when such an activity occurs
in areas that have been judged to be paleontologically sensitive based on the distribution
of known fossil localities or of potentially fossil-bearing sedimentary formations
(cf. Demere and Walsh, 1993).
A paleontological resource assessment of the de Jong property/Morning Ridge
project site (see attached vicinity map) was conducted to evaluate the potential for
discovery of unrecorded paleontological resources that might require a paleontological
mitigation and monitoring program to be implemented. The paleontological assessment
involved examination of published geologic maps, evaluation of the local formational
units for their paleontological resource potential (cf. Demere and Walsh, 1993), a field
survey, and examination and interpretation of locality collection records of the San Diego
Natural History Museum for data on nearby fossil localities.
ASSESSMENT
The de Jong property/Morning Ridge project is an approximately 33.4 acre parcel
of land within the central part of Carlsbad east of Black Rail Road and north of the
Poinsettia Lane extension (under construction). The project is situated on a remnant of a
high marine terrace (Clairemont terrace of Kern and Rockwell, 1992 [=1993])
overlooking a northward draining canyon that is tributary to Canyon de las Encinas
(Palomar Airport Road alignment) on the north. The project site is centrally located
between Canyon de las Encinas on the north, El Camino Real on the east, Batiquitos
Lagoon on the south, and the Interstate 5 freeway on the west. This project site occupies
the northwest quarter of the southeast quarter of Section 22 of Township 12 South, Range
4 West, SBBM, as shown on the U. S. Geological Survey 7.5-minute, 1:24000 scale,
topographic map of the Encinitas, Calif, quadrangle (1968 edition, photorevised 1975).
The project property is overlain by marine terrace sediments (Qt4 on the geologic
map of Tan and Kennedy, 1996, pi. 2) that are typically assigned to the Lindavista
Formation. The high marine terraces in northern San Diego County have yielded little in
the way of fossil materials and the only published fauna from the formation is from the
Tierrasanta area of San Diego (Kennedy, 1973) many miles to the south. The collection
records of the San Diego Natural History Museum (SDSNH), however, show two
localities in the Lindavista Formation in the vicinity, one along the eastern margin of the
subject property. Both fossil localities are in the basal sediments of the Lindavista
Formation, at an elevation of about 319 feet. Fossils include marine bivalve mollusks
I
I
I
I
I
I
I
I
I
I
I
I
I
I
I
I
I
I
I
Paleontological Monitoring for the Morning Ridge Project
that have bored into the underlying Eocene sediments. The contact between the
Lindavista Formation and underlying Eocene sediments is exposed along the mesa edge
on the eastern margin of the subject property, and westward along the 320 foot (+/-)
contour along the eastern edge of proposed house lots 8 through 28 (see Attachment),
which overlook the present canyon. Paleontological monitoring of grading/earthmoving
activities in this part of the project will be necessary to recover any fossils that are
exposed during this phase of construction. The highest elevations on the subject property
are in the southwest corner, but the sediments there are mainly eolian fine-grained sands
that are characterized by the presence of small ironstone concretions typical of this part of
the Lindavista Formation. The presence of fossils in this upper part is less likely.
In the central Carlsbad area, and including the subject project, the marine terrace
materials (Qt4, or Lindavista Formation) overlie marine, estuarine, and terrestrial
sediments assigned to the middle Eocene (40-44 million year old) Santiago Formation
(informal "member B") (Tsa on the geologic map of Tan and Kennedy, 1996, pi. 2).
"Member B" of the Santiago Formation locally has yielded very important marine
invertebrate and terrestrial vertebrate faunas, as well as paleobotanical specimens (San
Diego Natural History Museum collection records), and is assigned a "high
paleontological resource sensitivity" by Demere and Walsh (1993, p. 21). The Santiago
Formation, if encountered below the Lindavista Formation, would also require
paleontological monitoring in order to recover any fossils that might be exposed during
grading/earthmoving activities.
SUMMARY
A paleontological resource assessment of the de Jong property/Morning Ridge
project in the central part of Carlsbad, San Diego County, California, supports the
necessity of a paleontological monitoring and mitigation program during grading and/or
earthmoving activities that may occur in conjunction with developing the property. The
subject property is overlain by middle to lower Pleistocene marine terrace sediments (the
Lindavista Formation) that have been assigned a "moderate paleontological resource
sensitivity" by Demere and Walsh (1993), and underlain by the middle Eocene Santiago
Formation, which has been assigned a "high paleontological resource sensitivity." The
presence of known fossil localities that have yielded marine invertebrate fossils from the
basal Lindavista Formation on the east side of the property, and at another locality close
by to the southeast, support the necessity of paleontological monitoring, particularly at or
near the contact of the Lindavista Formation and underlying Eocene sediments
(approximately equivalent to the 320 foot contour level), which are exposed along the
eastern margins of proposed house lots 8 through 28.
Paleontological Monitoring for the Morning Ridge Project
REFERENCES
Demere, T. A., and Walsh, S. L. 1993. Paleontological resources, County of San Diego.
Unpublished report prepared for the San Diego County Department of Public
Works, San Diego, California. 68 pp., figs. 1-3, 8 map sheets.
Kennedy, G. L. 1973. A marine invertebrate faunule from the Lindavista Formation,
San Diego, California. Transactions of the San Diego Society of Natural History,
17(10): 119-127, figs. 1-3.
Kern, J. P., and Rockwell, T. K. 1992 [1993]. Chronology and deformation of
Quaternary marine shorelines, San Diego County, California. In Fletcher, C. H.,
ffl, and Wehmiller, J. F., eds., Quaternary coasts of the United States: Marine and
lacustrine systems. SEPM (Society for Sedimentary Geology), Special
Publication, no. 48: 377-382, figs. 1-2, tables 1-4.
Tan, S. S., and Kennedy, M. P. 1996. Geologic maps of the northwestern part of San
Diego County, California. California Division of Mines and Geology, Open-File
Report 96-02, pis. 1-2 (map sheets, 1:24,000).
f,ANOW AZUA HSDIONDA MAP NO. 323
OCEAN BLUFF
.03-00 AVIARA
RELOCATED 16' S.D.G. <fc £.
ACCESS ROAD
DEJONG, CARLSBAD / CT 98-05