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J. H. KLEINFELDER & ASSOCIATES <br /> File No. 5-1008-35 <br /> May 17, 1985 <br /> Page 5 <br /> SITE GEOLOGY <br /> The site is underlain by consolidated alluvial deposits of the Laguna Formation <br /> overlying the Mehrten Formation. The Laguna Formation consists of consolidated gravels, <br /> sandstones, and siltstones. The slightly older Mehrten Formation generally consists of grey <br /> to tan-brown sandstone and siltstone, with conglomerate layers and ciaystone or mudstone. <br /> The formations are generally overlain by residual soil or recent alluvial deposits except <br /> where exposed by the current landfill operations. <br /> FAULTS AND SEISMICITY <br /> The major faults which have historically produced earthquakes of greatest magnitude <br /> in Central California are the Calaveras, Hayward and San Andreas faults in the Coast <br /> Ranges; the Midland and Green Valley faults on the west side of the Great Valley; and the <br /> Sierra Nevada and Owens Valley faults east of the Sierra crest. Focal faults include <br /> numerous small shear zones and two major fault zones, the Bear Mountains and Melones, <br /> which make up the Foothills fault system. Plate IV of this report indicates the position of <br /> the Foothill Landfill site in relation to the major fault zones of Central California. Also <br /> shown on Plate IV are earthquake epicenters with recorded Richter magnitudes of 5.0 or <br />