Appendix E - Geology and Soils Geotechnical Supporting Information COMBINED

LESTER-SHRINER PROPERTY 132-8-2 Page 3 The approximate locations of the recent test pits and borings are also shown on the Site Topographic & Preliminary Geologic Map, Figure 2. Logs of the recent explorations are included in Appendix A. 1.5 ENVIRONMENTAL SERVICES Cornerstone Earth Group also provided environmental services for this project, including a Phase 1 site assessment; environmental findings and conclusions are provided under separate cover. SECTION 2: REGIONAL SETTING 2.1 GEOLOGICAL SETTING The site is located in the western Diablo Range of the Coast Ranges structural and geomorphic province of California. This represents one mountain range in a series of northwesterly-aligned mountains forming the Coast Ranges geomorphic province of California that stretches from the Oregon border nearly to Point Conception. In the San Francisco Bay area, most of the Coast Ranges have developed on a basement of tectonically mixed Cretaceous- and Jurassic-age (70- to 200-million years old) rocks of the Franciscan Complex. Locally younger sedimentary and volcanic rocks cap these basement rocks. Still younger surficial deposits that reflect geologic conditions for the last million years or so cover most of the Coast Ranges. Rocks of two main basement complexes juxtaposed by major regional faults are exposed in the East Bay hills and Diablo Range. These are the Franciscan Assemblage and the Coast Range Ophiolite. The basement complexes are unconformably overlain by Mesozoic and Cenozoic sedimentary and volcanic rocks. These two Mesozoic basement complexes are the Franciscan Complex and the Great Valley Complex (Graymer, 2000). The ophiolite rocks are the remnants of arc-related oceanic crust. The Great Valley Sequence is composed of turbidutes (sandstone, conglomerate and shale) of Jurassic and Cretaceous age that were deposited on top of the crustal rocks. A sequence of unnamed Cretaceous rocks (Ks) that consists of sandstone with siltstone and shale is also exposed in steep portions of the East Bay Hills both north and south of Niles Canyon (Graymer et al., 1996). Tertiary rocks in the map area include Paleocene to Miocene marine sedimentary rocks that unconformably overlie the Mesozoic basement rocks (Graymer and others, 1996). Bedding in Cretaceous and Tertiary geologic units in the map area is generally steep and locally overturned, attesting to the considerable tectonic deformation that has taken place. Several northwest-southeast trending synclines have been mapped in the hills between the Hayward Fault and the Calaveras Fault (Graymer et al, 1996). Published geologic maps indicate the site is in an area dominated by a northwest trending band of tertiary age marine sedimentary units (Dibblee, 1980; Dibblee 2005,) that have been faulted and folded by regional forces. A portion of the Dibblee and Minch map of 2005 is reproduced in as Figure 3. Dibblee shows northwest trending synclines and anticlines located on the north side of Highway 580. The geologic units mapped as trending through the site include the following: an unnamed Miocene siltstone and clay shale (Tmc), the Miocene Clairmont Shale member of the Monterey Formation (Tm), an unnamed Miocene sandstone (Tms) and an Ii! CORNERSTONE EARTH GROUP