PaleoBios, Volume 15, Number 4, Pages 78-80, May 24, 1993 A Preliminary Note on the Arvin Landfill Local Fauna (?Holocene), Kern County, California Leslie P. Fay1 and Kenneth R. Thiessen2 BioSystems Analysis, Inc. Present addresses: iColuber Consultants, P.O. Box 682, Winnebago, IL 61088-0682; 2 237 SE 87th Avenue, Portland, OR 97216 INTRODUCTION As part of an ongoing investigation of potentially fossiliferous units that are disturbed by various development activities in California's Central Valley, we have tested a number of artificial exposures for the presence of small fossils. Among the public agencies that have expressed an interest in preserving paleontological resources is the Kern County Public Works Department. Public Works is responsible for the operation of more than a dozen landfills where periodic expansion creates new exposures at weekly to yearly intervals. Some of these landfills are developed in geologic formations dominated by fine-grained sediments known to produce fossils, while others are in units where the occurrence of fossils is rather unlikely because of metamorphism, high energy-of- deposition, etc. We have examined exposures at landfills placed in other geologic units for which the potential to produce fossils is simply unknown. PROCEDURE One of us (KRT) collected three 18-liter sediment samples at the Arvin Landfill, located 25 km southeast of Bakersfield, Kern County (Figure 1), in the southeastern corner of the San Joaquin Valley near the base of the El Tejon Range (NW1/4, section 31, T.31S., R.29E.). The surficial geology of the area is mapped as Quaternary "older alluvium" [Late Pleistocene]- alluvial fans (north half of landfill site) and Quaternary basin deposits [Holocene to Late Pleistocene] (south half of site) (Bartow, 1984). Samples were washed through screens to yield concentrate of two size fractions: greater than 1.5 mm particles, and less than 1.5 mm but greater than 0.7 mm particles. The larger size-fraction was sorted completely, a 25% subsample of the smaller fraction was examined. We did not undertake detailed recording and interpretation of site geology because our initial sampling was a fortuitous effort under limiting Figure 1. Map noting the location of the Arvin Landfill Local Fauna in Kern County. California. time constraints. The landfill is scheduled to operate for about fifteen years, access can be requested from Kern County Public Works Department. RESULTS Sample 1, from a coarse, cross-bedded sand ca. 8.5 m below surface on the west wall of the rectangular excavation, did not yield fossils. Sample 2 was taken from a grey clay layer (ca. 05 m thick) directly above Sample 1. Bone, tooth fragments, and bone fragments representing at in New Additions to the Pleistocene Vertebrate Record of California (R. G. Dundas and D. J. Long, eds.), PaleoBios v.15. Fay and Thiessen Arvin Landfill Local Fauna Page 79 ... TABLE 1. Taxonomic Lists - Arvin Landfill local fauna (University of California Museum of Paleontology (UCMP) locality V93068). Arvin #2 Leporidae: lower molar (UCMP specimen number 139151) IThomomys: I frag. (UCMP 139150) Microtus sp.: upper molar frag. (UCMP 139152), R femur, prox. frag. (UCMP 139153), R calcaneum (UCMP 139154). Arvin #3 IHyla: tibiofibula (UCMP 139157) Lacertilia: phalanx (UCMP 139158) Leporidae: lower incisor frag. (UCMP 139159), terminal phalanx (UCMP 139160). Dipodomys sp.: upper incisor frag. (UCMP 139161), upper molar (UCMP 319162). Neotoma sp.: Li (UCMP 139163), Lm2 (UCMP 139164), Lm3 (UCMP 139165), lower molar frag. (UCMP 139166), lower molar frag. (UCMP 139167), molar frag. (UCMP 139168), L ulna (UCMP 139169). Microtus sp.^ LM frag. (UCMP 139170), upper molar frag. (UCMP 139171), molar frag. (UCMP 139172), 3 enamel frags. (UCMP 139173). Canidae: R mandible frag, w/c-pl (UCMP 139178), tooth root frag. (UCMP 139179). least three mammal taxa were recovered (Table 1). Sample 3 was removed from a coarse sand lens within a 0.3 m thick clay layer on the east wall of the excavation at ca. 7.5 m below surface. At least five mammal taxa, one frog, and one lizard are represented (Table 1). From faunal character and stratigraphic/geomorphic setting, we tentatively consider the Arvin landfill site to be of early Holocene or Wisconsinan age. All taxa represented are first published occurrences for the area, simply because Arvin is the first late Quaternary locality reported from the southeast corner of the San Joaquin Valley. Although the sample is small for paleoenvironmental reconstruction, each taxon has modern representatives living at or near the locality. DISCUSSION We feel it is especially important to note that the Arvin fossils were recovered from Quaternary alluvium. In contract-paleontologic (= "salvage" or "mitigation") studies, this time interval and sediment type have often been pronounced devoid of fossils (by persons other than Quaternary paleontologists!) and therefore not considered for salvage opportunities. Overall, such an uninformed determination is most certainly not accurate. Quaternary vertebrate samples from the southern San Joaquin Valley exist in museum collections but few have been thoroughly studied and published. The well-known McKittrick and Maricopa Brea localities are located 75 km and 50 km, respectively, to the west of Arvin across the San Joaquin Valley. At much higher elevations on the western flank of the southern Sierra Nevada, the potential for recovering Page 80 Arvin Landfill Local Fauna Fay and Thiessen Quaternary vertebrates has been realized (Kings Canyon packrat middens; Mead et al., 1985). The Arvin Landfill study, combined with results from these faunas, indicates that a larger effort should yield significant information to aid in reconstructing the Quaternary history of the area. Great potential exists to correlate new biostratigraphic and paleoenvironmental data with well-known localities, as well as the emerging picture of Quaternary environments in the Great Basin, Mojave Desert, and Los Angeles Basin. ACKNOWLEDGEMENTS Preliminary paleontological study at the Arvin Landfill was carried out with the cooperation of the Kern County Public Works Department. We particularly wish to thank Michael Theroux for his encouragement and advice. Thanks also to Julia Sankey for washing the matrix and sorting much of the concentrate, and to Liz Barnosky for curating the collection. Comments by Howard Hutchison and an anonymous reviewer helped us improve the paper. This study is a product of the Paleontologic Resource Management Program of BioSystems Analysis, Inc. REFERENCES Bartow, J. A. 1984. Geologic map and cross- sections of the southeastern margin of the San Joaquin Valley. U.S. Geological Survey Miscellaneous Investigation Series 1-1496 (2 sheets). Mead, J. L, T. R. Van Devender, K. L. Cole, and D. B. Wake. 1985. Late Pleistocene vertebrates from a packrat midden in the south-central Sierra Nevada, California. Current Research in the Pleistocene, 2:107-108.