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PALEONTOLOGY PROJECTS

Portola Center (Tract 15353) Housing Subdivision Project, City of Lake Forest

The Portola Center (Tract 15353) Project involved the removal and redistribution of over 1.8 million cubic yards of earth on a 95-acre site in the foothills of the Santa Ana Mountains for the construction of 331 single-family homes, a 256-unit townhouse complex, streets, parks, and open spaces.  Impacts to potential paleontological resources at the project were addressed in the City of Lake Forest’s Opportunities Study Area Final Program Environmental Impact Report, which based its findings and conclusions regarding paleontological resource mitigation measures upon BFSA’s paleontological assessment report, pursuant to CEQA regulations.  In the assessment, BFSA concluded that the underlying geologic formations were highly sensitive regarding the potential to yield fossils.

 

After over four years of monitoring at the project, an abundance of deep-water marine invertebrate and vertebrate faunas from the middle to late Miocene Epoch (nine to 14 million years old) were recovered.  Over 320 fossils were obtained from multiple field collections assigned to 76 museum localities.  Notable fossils included a very large, new species of right whale, the skull and upper body bones of a toothed whale preserved inside a boulder, and the rear feet of a walrus.  Over 15 species of fossil fish and sharks were recovered, including bones from the six-foot-long, saber-toothed salmon and teeth from an ancient species of mako shark and the giant Megalodon.  The most common fish was Ganolytes cameo, an extinct species of sardine over a foot long with fingernail-sized scales.  The fossil mollusk collections represent a rarely seen Miocene assemblage of deep-water species.  These specimens are currently under a joint study by United States Geological Survey and BFSA paleontologists.  The results of the study will be published by 2021.

Residential Home, Tourmaline Surfing Park, La Jolla, City of San Diego

BFSA has extensive experience guiding residential projects to meet rigorous City of San Diego-mandated Mitigation Monitoring and Reporting Program guidelines for paleontological resources.  For example, a new bluff-top real estate project involved extensive underground excavation for a subsurface garage and other amenities.  The homesite is perched at the edge of a seaside cliff overlooking Tourmaline Surfing Park.  The geology is spectacularly expressed on the face of the 70-foot-high cliff, accounting for multiple scientific publications over the past 50 years and visits by thousands of geology students.  Most of the bluff is composed of the 47-million-year-old Mount Soledad Formation, but ironically, fossils from this extensive outcrop were unknown.  As a result of monitoring during drilling and excavation for the building’s subsurface structures, impressions of a diverse assortment of fossil shells were discovered from this formation for the first time, and, as a result, a scientific article authored by BFSA scientists with assistance from a United States Geological Survey paleontologist is forthcoming to document the significance of the finds.

Allegro Tower, Pinnacle Marina Tower, and Parkloft Apartments Projects, Downtown San Diego

Downtown San Diego overlies geologic formations rated as having a “High Sensitivity” by the County of San Diego and the City of San Diego for the potential to yield paleontological resources.  These sensitivity ratings are based upon the occurrence and distribution of known fossil localities.  Dr. George Kennedy of BFSA was consulted to advise the panel responsible for drafting the City of San Diego’s final paleontological mitigation, monitoring, and reporting guidelines.  Dr. Kennedy’s field and managerial experience include dozens of downtown projects, the majority of which yielded fossils.

 

For example, the Allegro Tower, Pinnacle Marina Tower, and Parkloft Apartments projects are a part of downtown San Diego’s vast, ongoing, two-decade-long redevelopment endeavors, and impacts to rich, fossiliferous strata are common.  Typically, large apartment towers require underground parking that goes 50 feet deep or deeper.  As a consequence, layer after layer of sediments, representing multiple transgressions and regressions of the sea that are a result of glacial ice fluctuations, can be viewed.  These layers of sediments frequently contain a wealth of fossil shells.  BFSA scientists were able to distinguish and separate shell faunas at these and other downtown projects; as a result, the chronologic order of middle to late Pleistocene sea level advances and withdrawals can be interpreted with greater ease and precision within the layers of sediments that are encountered.  Headed by Dr. Kennedy of BFSA, the results from these projects were published in a report for the Western Society of Malacologists.  This report continues to influence the BFSA monitoring staff and serves the scientific community of San Diego at large as a valuable, subsurface guide for subsequent downtown projects.

Salt Creek Flood Control Channel Project, Stage 6, Riverside County

The Riverside County Flood Control and Water Conservation District retained BFSA to fulfill CEQA requirements for the channelization of a natural drainage.  Stage 6 involved grading and excavation activities for a three-mile segment of the Salt Creek Channel roughly between Menifee and Diamond Valley Lake.  The bones and teeth of large Ice Age mammals were recovered, including those of giant ground sloth, black bear, horse, camel, two species of bison, and numerous unidentifiable bones.  Additionally, the milk tooth of a young mastodon was recovered, as well as a partial skeleton of a mammoth that included a 4.5-foot-long tusk.  The condition of the bones suggests that animals trampled the mammoth skeleton before its burial.  Wet screening techniques yielded a species of freshwater or land snail.  These localities are partly correlative with the rich vertebrate faunas of the Domenigoni Valley just to the east, and serve to add additional information to reconstruct the animal populations of southern California during the Pleistocene.

4S Ranch Project, San Diego County

The 4S Ranch Project involved over 2.6 square miles for the construction of a new residential community between Escondido and Black Mountain along the west side of Interstate 15, in unincorporated San Diego County.  Draft and final EIRs were prepared under CEQA requirements, outlining the need for a Mitigation Monitoring and Reporting Program to reduce potential impacts to fossil resources.  BFSA met the challenge to satisfy this task, which involved the unraveling of the complex geologic relationships of interfingering marine and nonmarine stratigraphy, collecting very small to extraordinarily large fossils, managing multiple field crews, and recruiting top scientists and specialists to analyze the specimens.  The detailed geology of this area of the county, while broadly known, was poorly understood before the project was initiated.  After eight years of monitoring, a wealth of Eocene floras and faunas were revealed, including the fossilized remains of leaves from a variety of plants and trees, bivalve and gastropod mollusks, fish and rays, crocodiles, soft- and hard-shelled turtles, snakes, wading birds, lemur-like primates, rodents, carnivores, tapirs, brontotheres, rhinoceros, and other primitive hoofed mammals.  A 48-foot-long log of petrified wood and new species of freshwater algae and land snail were also found.  This project remains one of the most scientifically important projects undertaken by BFSA, as the value of the collection underscores interpretations of the region’s climatic and biotic record 45 million years ago.

Lake Forest Sports Park Project, City of Lake Forest

The City of Lake Forest proposed a new sports and recreation complex on a 90-acre parcel that included the construction of six baseball/softball fields, up to five soccer fields, playgrounds, hard courts, an amphitheater, and a 30,000-square-foot recreation center.  Under CEQA, the City of Lake Forest's EIR identified potential impacts to fossil resources likely present at the site.  BFSA was retained by the City to fulfill the requirements specified by the EIR to mitigate potential impacts to fossil resources.  At stake was the six-million-year-old Oso Member of the late Miocene Capristrano Formation, one of the most fossiliferous geologic units in coastal southern California, which is famous for yielding the well-preserved remains of a variety of extinct whales, sea cows, pinnipeds, fish, and sharks.  Extensive mass grading for future playing fields and sports facilities exposed over a hundred feet of sandstone stratigraphy.  As a result, 98 fossil localities were recovered, mostly by plaster-and-burlap methods, and are represented by more than 150 bones and teeth of past marine life.  These include bones from right whales, rorqual whales, pygmy baleen whales (considered rare), sperm whales, sea cows, flounders, and saber-toothed salmon, as well as, unusually, the leg bone of a camel.

Imperial Landfill Expansion Project, Imperial County

BFSA was contracted to fulfill Conditional Use Permit measures and Final EIR requirements under CEQA that required a Mitigation Monitoring and Reporting Program to reduce potential impacts to paleontological resources to less than significant at an active landfill north of El Centro in Imperial Valley, California.  Paleontological monitoring by BFSA staff during grading activities at the Imperial Landfill Expansion Project resulted in a diverse collection of early Holocene remains of small to microscopic animals that once inhabited the waters of ancient Lake Cahuilla.  Using wet-sieving techniques, small to tiny freshwater snails, such as Physella humerosa, Tryonia protea, and Pyrgulopsis longinqua were recovered, along with microscopic ostrocod valves (bivalved crustaceans), throat-teeth of a fish known as the bonytail chub, and gyrogonites (reproductive growths) of calcareous alga.  The pearly shells of the California floater (Anodonta californiensis), a two-inch-long freshwater mussel, were collected from what were their living positions, having died there many thousands of years ago.

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