3.1 Geology and Soils
GEOLOGY AND SOILS
3.1
This section of the EIR/EA provides general information and a regional perspective on coastal geology,
beaches and shoreline configuration, tides and sea level changes, wave processes, littoral processes.
Existing geologic conditions were based on several reports and documents, including the San Diego
Regional Beach Sand Project Offshore Sand Investigations (Sea Surveyor 1999); Shoreline
Morpholog y Study, San Diego Regional Beach Sand Project (Moffatt & Nichol 2000a) which is
Appendix C; the two EnvironmentalAssessments for beach replenishment (Department of the Navy 1997a,
1997b); and Beach Sand Transport and Sedimentation Report prepared by Frederic R. Harris, Inc.
(FRH 1997).
For purposes of this report, geology and soils include coastal geology and littoral processes of the receiver
sites, and the composition of the offshore borrow sites. Coastal geology and beach configuration are
determined primarily by wave forces acting on the geologic framework. These factors account for the
area's rugged undersea and land topography, including the narrow continental shelf, the rocky substrate
under most beach areas, the thin layer of sediment, as well as coastal marine terraces, sea cliffs, and
lagoons.
The following subsections focus on the existing geologic conditions and littoral processes that make up the
individual receiver sites, and the composition of the proposed borrow sites. More information regarding
turbidity issues can be found in Sections 3.3 and 4.3 (Water Resources), while more detailed lagoon
information is found in Sections 3.2 and 4.2 (Coastal Wetlands).
Littoral Processes of the Three Littoral Cells
3.1.1
Oceanside Littoral Cell
The Oceanside Littoral Cell extends from Dana Point, in Orange County, south to the Scripps-La Jolla
Submarine Canyon system at La Jolla Shores, near the foot of Mount Soledad (refer to Figure 1-2). The
Oceanside Harbor complex is located approximately in the middle of this littoral cell. The harbor jetties
interrupt the natural flow of sand and to a large extent divide the cell into sub-cells north and south of
Oceanside Harbor. Receiver sites are located along the southern half of the Oceanside Littoral Cell.
Page 3.1-2
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