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» 3 would be completed during separate periods so that SART users can be detoured to the trail on the opposite side of the Santa Ana River at 5th Street. There are gates and ramps located on both sides of the SART at 5th Street that provide access to bicyclists and pedestrians for these detours. Details regarding the detours are being coordinated with Orange County Parks. Other short‐term closures of up to 15 minutes would be allowed with flagmen. A temporary detour within the river bed may be required as a contingency. This would involve construction of dirt and gravel ramps with asphalt topping to and from the SART and the river bed. Construction vehicles would access the Santa Ana River from the gate and ramp at the County of Orange access road at the northwest corner of the bridge, and would use the existing concrete access ramp into the river approximately 250 ft west of the proposed Project Area. All access roads to the SART that are utilized by construction vehicles or for detour routes would be reconstructed and restored to pre‐construction conditions or better prior to project completion. Excavation associated with the various components of the proposed Project is expected to extend to a depth of 2 ft for the roadway widening, 4 ft for the utility relocations, 6 ft for the river pier footings, and 5 to 15 ft for the bridge abutments (personal communication, WKE, Inc., April, 2018). METHODS LSA examined geologic maps of the Project Area and reviewed relevant geological and paleontological literature to determine which geologic units are present in the Project Area and whether fossils have been recovered from those or similar geologic units elsewhere in the region. A search for known fossil localities was also conducted through the Natural History Museum of Los Angeles County (LACM) in order to determine the status and extent of previously recorded paleontological resources within and surrounding the Project Area. RESULTS Literature Review The proposed Project is located at the northern end of the Peninsular Ranges Geomorphic Province, a 900‐mile‐long northwest‐southeast‐trending structural block that extends from the Transverse Ranges in the north to the tip of Baja California in the south (California Geological Survey, 2002; Norris and Webb, 1976). This province is characterized by mountains and valleys that trend in a northwest‐southeast direction, roughly parallel to the San Andreas Fault. The total width of the province is approximately 225 miles, extending from the Colorado Desert in the east, across the continental shelf, to the southern Channel Islands (i.e., Santa Barbara, San Nicolas, Santa Catalina, and San Clemente) (Sharp, 1976). It contains extensive pre‐Cenozoic (more than 66 million years ago [Ma]) igneous and metamorphic rock covered by Cenozoic (less than 66 Ma) sedimentary deposits (Norris and Webb, 1976). Within this larger region, the proposed Project is located in the Los Angeles Basin, a broad alluvial lowland bounded to the north and east by the San Gabriel and Santa Ana Mountains, respectively, and by the Pacific Ocean to the southwest (Yerkes et al., 1965). The Basin is underlain by a structural depression that has discontinuously accumulated thousands of feet of marine and terrestrial