3.5 Cultural Resources
stand, at about the 80-90 foot depth contour below current sea level, consistent with the sea level
fluctuations which occurred during the 12,000 - 10,000 B.P. time period. A stable sea level would have
created shorefront erosionand the resulting steeper profile. This interpretation is supported by the presence
of boring clam clasts at 1 to 3 foot depth, suggestive of a rocky intertidal environment.
The eastern portion of SO-7 presents a contrasting geologic structure. The side scan sonar image reveals
a rippled, sand covered, bedform for much of this region, with an exposure of rough bedrock in the
southeast portion of the grid. The sub-bottom profiler data suggest that a preserved paleolandform, a
channel meander feature, is present along the eastern edge of the grid. Using the vibracore as a guide, a
geological cross-section of the SO-7 site indicates bedrock outcrops near the sea floor at the north and
south ends of the grid, with the preserved paleochannel in the central portion. The channels is filled
primarily by intertidal sediments, with a pre-transgression fluvial deposit at the bottom, and offshore marine
sediments at the top of the section. Intertidal species are represented in two of the cores by Donax gouldii
(1 to 10 feet).
The onshore area is environmentally very rich today and numerous prehistoric sites are recorded in the
vicinity of Batiquitos Lagoon. The potential for occurrence of archaeological materials within SO-7
appears to be moderate. Much of the sand deposit at this site is intertidal material, with low probability for
direct prehistoric habitation. Since this is a sand bar at a lagoonal entrance, the probability for occurrence
of a prehistoric archaeological site may be increased. In the southern portion of the site, there is a
preserved basal contact between fluvial (pre-transgression) and intertidal (transgression) sediments. The
preservation of sites at this location may be problematic, since erosion and mixing would likely accompany
the intertidal deposition.
Historical Results
Although the project area lies within a zone assessed as high sensitivity for the presence of historic
shipwrecks, no shipwreck sites are recorded within this proposed borrow site. No side scan sonar targets
suggesting the presence of cultural material were recorded during the survey phase.
SO-6
The water depth varies from 58 feet along the eastern edge of the grid to 120 feet along the western portion
of the grid. A small rectangle within the eastern portion of SO-6 has been designated as a source site for
Regional Beach Sand Project EIR/EA
Page 3.5-9
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