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The surficial geology and profile of the soils were studied in 14 backhoe pits across the project site. The layer of silt and clay exposed on the surface, overlying the gravels, was observed to vary in thickness from 0 to 3 feet, averaging about 2 feet. Gravels encountered ranged in size from 114 inch to 4 inches in diameter. The principal rock types observed in the gravel clasts - were graywacke sandstone and chert. The contact between the surficial silts and clays, where present, and the underlying gravels is ' gradational in most instances. This is to be expected in the alluvial fan aggradational depositional environment present at the site. The silt/clay layer often grades into a gravelly silty clay, with rock clasts up to 112 inch diameter. The sand content in these zones can range from insignificant to predominant. This gravelly clay can transition into a clayey/silty gravel with larger clasts, where the percentage of sand and gravel exceeds the silt/clay content. The gravels at this site most often contain a significant percentage of silts and clays, typically from 10% to 50%. In general, as the clast size of the gravels increases up to the 4 inch diameter observed, the sand content increases with it. This conversely means that the silt/clay content generally decreases with the coarser gravels. + ± SOILS OF AGRICULTURAL IMPORTANCE Data provided in this section is based on visual inspection of the soil profiles in 14 backhoe pits. Using soil survey and site maps, the location of each pit was randomly selected to be representative of the soils of the project. Selected samples of soil were analyzed for organic matter and alkaline earth carbonates. The Soil Conservation Service (SCS) defines "topsoil" as the upper pan of the soil, which is the most favorable material for plant growth. It ordinarily has a higher content of organic matter. The proposed expansion consists of four soil types: Cortina gravelly sandy loam (SCS Map Symbol `4 r 137), Xerofluvents-Xerothents complex (SCS Map Symbol 278, Zacharias clay loam (SCS Map Symbol 281)� and Zacharias gravelly clay loam (SCS Map Symbol 282). The Zacharias soils are designated as prime farmland where Firrigated. SEE PLATE 3. Topsoil Identification by Percent Organic Matter i In addition to physical identification of soil horizons, laboratory assay was made on a limited number of samples for organic matter. These assays identified an accumulation of 0.9 to 1.1 LA 1., percent organic matter in the top 6 inches of the soil. The zones from 6 inches to 24 inches and deeper contained 22 to 64 percent less organic matter. Agricultural Use Phase I covers about 164 acres. Approximately 43 acres are presently permitted and are being mined. The land surface and native vegetation of this area have been extensively disturbed by past shallow mining excavations in Hospital Creek stream channel and by overgrazing of livestock. Phases 11, II1, and IV cover about 337 acres. This area is planted to mature, { producing almond trees which are non-cultivated and irrigated by drip systems. Agricultural . 2 Report Rev.2-0620.95 ACRO ENVIRONMENTAL SERVICES 0 A Division of Condor Earth Technologies, Inc. Condor v.� i I