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north (15.9 percent of the time). Calms occur 6.9 percent of the time. A wind <br /> rose (Figure 5) developed from the Stockton WB Airport data provides wind <br /> direction information. The mean annual wind speed is 8.2 miles per hour. <br /> 3.3 GEOLOGY AND SITE SOILS <br /> 3.3.1 REGIONAL GEOLOGY <br /> The Forward Landfitf is located�mear°the geographic center of the Great Valley of <br /> California. The Great Valley lies between the Sierra Nevada Range on the east <br /> and the Coast Range on the west. The Great Valley is an asymmetrical structure <br /> trough filled with a thick sequence 6f flat lying marine and continental pediments. <br /> Ground surface elevations at the site range from approximately 30 to 40 feet <br /> relative to mean sea level 4.z"sl),, ing genera4.,,t®..1he west. Regional <br /> topography is shown on Figure 3. Figure 6 illustrates the surface outcropping of <br /> regional geologic units near the site. _A_"brief summary of be type and origin of <br /> sediments underlying the region, from oldest to youngest, follows. <br /> Marine Sequence <br /> The marine sediments of the'Great Valley were deposited during the Cretaceous <br /> and Early Tertiary Periods (approximately 35 to 150 million years before present). <br /> These marine sediments were probably deposited in a miogeosyncline bound on <br /> the east by the developing Sierra Nevada Mountain range and on the west by the <br /> subducting Pacific Plate. This sequence of marine clays, silts, and sands includes <br /> (from oldest to youngest) undifferentiated upper Cretaceous sandstone and <br /> siltstone, undifferentiated Tertiary sandstone and shale, the Capay Shale, the <br /> Domengine Shale, the Nortonville Shale, and the Markley Formation. This <br /> sequence is approximately 5,250 feet thick under the site. <br /> Continental Sediment Sequence <br /> The Great Valley in the area around Stockton was uplifted at the end of the <br /> Eocene and was eventually cut off from the Pacific Ocean on the west by <br /> subduction and/or accretion events which uplifted or emplaced the present day <br /> Coast Ranges. Sediments derived from the eroding Sierra Nevada in the east and <br /> the Coast Ranges in the west were deposited in the Great Valley by rivers and <br /> Forward Landfill JTD 3-3 <br /> L:\Allied\2000.193\Reports\finaljtd:Sec-3.0:08/20/01 <br /> BRYAN A.STIRRAT&ASSOCIATES <br />