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INC <br /> 4.0 SOIL SITE ASSESSMENT <br /> 4.1 Regional Geology and Hydrogeology <br /> The study area is located in the Great Valley of California within the southern portion of <br /> the Sacramento Valley The subsurface geology generally consists of continental <br /> deposits, which are highly stratified, interbedded, coarse-grained sediments and fine- <br /> grained cohesive to lithified sediments that are present to depths of approximately 2,000 <br /> feet below ground surface Due to the lenticular nature of the subsurface stratigraphic <br /> units, it is difficult to determine the horizontal and vertical extent of formal and informal <br /> stratigraphic units within the subsurface Geologic formations and informal stratigraphic <br /> units underlying the site include, with respect to increasing depth the Younger Alluvium <br /> of Holocene age, the Older Alluvium of Pleistocene to Holocene age, the Turlock Lake <br /> Formation of Pleistocene age, the Laguna Formation of Pliocene age, the Mehrten <br /> • Formation of Pliocene age, and the Valley Springs Formation of Miocene age (Page 1986) <br /> The formations of the Lodi area are described in detail below <br /> The Younger Alluvium, Turlock Lake, and Laguna Formations are largely dominated by <br /> granitic source material These sediments tend to be brownish in color Particles are <br /> composed of quartz, feldspar, and mica from the igneous and metamorphic source rocks <br /> of the Sierra Nevada The Turlock Lake and Laguna Formations are composed of weakly <br /> consolidated sands, gravels, silts, and clays The Turlock Lake Formation is largely <br /> identified from topographic position and soil profile characteristics (Page 1986) <br /> • 08220010 011 24 <br />