SITE INFORMATION AND CORRESPONDENCE

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5.8:PALEONTOLOGICAL RESOURCES Formation within the area. These mapping units,which are considered here to be facies of the Modesto Formation, are identified by symbols alone: Geological units identified by Marchand and Atwater (1979)within two miles of the project site,are the following: Qm Undifferentiated Modesto Formation. Moderately consolidated silty clay, silt, sand and gravel deposits of alluvial origins. Qm1 Lower member of the Modesto Formation consisting of arkosic alluvium of the Mokelumne River alluvial fan; chiefly sand;probably glacial outwash Qm2 Upper member of the Modesto Formation,undifferentiated The mapped distribution of these geological units following Marchand and Atwater (1979) is displayed in Figure 5.8-1. Throughout the project area there also an overburden of disturbed soils and artificial fill that relates to the long history of agricultural as well as industrial development in the area. These disturbed soils and fill extend to varying depths depending on the activity area,but normally undisturbed sediment is not encountered above a depth of approximately 4 feet. 5.8.2.3.2 Results of the Resource Inventory A search of the UCMP database on May 25,2008 yielded records of 81 fossil localities within San Joaquin County;25 of these are invertebrate collections or microfossil samples. The rest of the localities have yielded vertebrate fossils. Many are from the fossiliferous Tertiary units exposed in the Coast Range foothills more than 20 miles to the southwest; additional records come from the foothills of the Sierra Nevada that start to rise about 10 miles to the east. Very few records appear to come from the axial portion of the Great Valley at these low elevations immediately adjacent to the Delta. All identifiable paleontological localities are more than one mile distant from the project site. No known paleontological sites occur within one mile of the project site including its linears. 5.8.2.3.3 Paleontological Sensitivity of the Project Site Paleontological sensitivity is the qualitative assessment made by a professional paleontologist taking into account the paleontological potential of the stratigraphic units present,the local geology and geomorphology, and any other local factors that may be germane. According to SVP (1995) standard guidelines sensitivity comprises (1) the potential for a geological unit to yield abundant or significant vertebrate fossils or for yielding a few significant fossils, large or small,vertebrate,invertebrate, or paleobotanical remains, and (2) the importance of recovered evidence for new and significant taxonomic, phylogenetic,paleoecological,or stratigraphic data (Table 5.8-1). SAC13713221082340008(LEC_5.8_PALEORES.DOC) 5.8-3