Appendix A Paleontological Analysis

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9/22/19 «P:\WKE1702\Paleo\September 2018 Submittal\Fairview Street Improvements_Draft Paleo Memo 090718.docx» 5 streams and debris flows coming down from higher elevations and generally form a fan or lobe shape at the base of hills and mountains (Morton and Miller, 2006). As noted above, only fossils from the middle to early Holocene (4,200 to 11,700 years ago; Walker et al., 2012) are considered scientifically important (SVP, 2010). These Holocene deposits overlie older Pleistocene deposits, which have produced scientifically important fossils elsewhere in the region (Jefferson, 1991a, 1991b; Miller, 1971; Reynolds and Reynolds, 1991; Springer et al., 2009). These older deposits span the end of the Rancholabrean North American Land Mammal Age (NALMA), which dates from 11,000 to 240,000 years ago (Sanders et al., 2009) and was named for the Rancho La Brea fossil site in central Los Angeles. The presence of Bison defines the beginning of the Rancholabrean NALMA (Bell et al., 2004), but fossils from this time also include other large and small mammals, reptiles, fish, invertebrates, and plants (Jefferson, 1991a, 1991b; Miller, 1971; Reynolds and Reynolds, 1991; Springer et al., 2009). There is a potential to find these types of fossils in the older sediments of this geologic unit, which may be encountered below a depth of approximately 10 ft. Therefore, these deposits are assigned low paleontological sensitivity from the surface to a depth of 10 ft and high sensitivity below that mark. Fossil Locality Search According to the locality search conducted by the LACM, there are no known fossil localities within the boundaries of the proposed Project. The LACM reports that the Project Area is underlain by deposits of younger Quaternary alluvium overlying older Quaternary alluvium (i.e., Young Alluvial Fan Deposits). The museum notes that these deposits typically do not contain scientifically significant fossils in the uppermost layers but, they may produce important fossils at depth. The closest vertebrate locality in these older Quaternary deposits is LACM 1339, south‐southwest of the Project Area near the top of the bluffs along Adams Avenue in Costa Mesa. This locality produced a specimen of horse (Equus) at a depth of 43 ft below the street. The next closest locality is LACM 2032, northeast of the Project Area near the intersection of Mission Road and Daly Street. That locality yielded specimens of mammoth (Mammuthus) and camel (Camelidae) at a depth of 15 ft below the top of the bluff. Locality LACM 4943, which is located northeast of the Project Area near the intersection of Glassell Street and Fletcher Avenue in Orange, produced a specimen of horse (Equus) at a depth of 8 to 10 ft below the surface. The LACM believes that shallow excavations in the Young Alluvial Fan Deposits in the Project Area are unlikely to encounter any scientifically important vertebrate fossils. However, the museum notes that deeper excavations into these deposits may encounter scientifically significant vertebrate remains and should be monitored to recover those remains. A copy of the letter describing the locality search results from the LACM is provided in Attachment C. CONCLUSIONS AND RECOMMENDATIONS Any Artificial Fill present within the Project Area has no paleontological sensitivity, the Very Young Wash Deposits have low paleontological sensitivity, and the Young Alluvial Fan Deposits have low paleontological sensitivity from the surface to a depth of 10 ft and high paleontological sensitivity below a depth of 10 ft. The majority of project excavation is anticipated to be shallower than a depth of 10 ft, with only the bridge abutments possibly extending to a depth of 15 ft. However,