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 Solana Beach Coastal Preservation Association
August 20, 1998
Project No. 1831
Page 40
sandstone. The clay layers usually form the roofs and floors of the sea caves, while faults
and joints control the sides.
Comparison of the 1990 and 1998 topographic profiles in Cross Section 2 suggests 4 to 6
feet of retreat of the sea cliff in the last eight years. The top of the bluff has retreated 0 to 4
feet in the last 6 years, based on comparison with February 24, 1992, aerial photographs in
our files. Accelerated subaerial erosion affects only a small part of the bluff below 529
Pacific Avenue. An active over-bluff drainage descends from the property line between 529
and 533 Pacific Avenue.
A seawall, riprap, and geogrid slope were constructed at 521 Pacific Avenue to repair
collapse of the largest sea cave in North County.
6.3
Reach 3 - Tide Park - 509 to 501 Pacific Avenue
This reach of the coast is a cove and pocket beach protected by headlands. The reach is
shown in Map and Photo 3. The back of the cove has been protected by a concrete
sandbag seawall that appears to have performed well except where repairs have been
required at both ends. The cove is protected by a substantial headland on the north and a
thin headland on the south that supported a lifeguard tower up to 1997. At the time of our
surveys, the average beach width within the cove was 60 feet.
6.4
Reach 4 - 475 to 235 Pacific Avenue
Reach 4 is characterized by a long straight sea cliff between two headlands. This entire
reach experienced extensive block falls during the El Nio of 1997-98. The near-vertical
seacliff was severely undermined by notching at the base, leading to overhangs that
collapsed in large blocks, carrying parts of the overlying and sloping upper bluffs with
them, and leaving unstable, near vertical cliffs in the lower portions of the weak marine
terrace deposits. During our field surveys, an active block fall had detached itself from the
coastal bluff below 269 Pacific Avenue. The reach is shown on Map and Photo 4, 5, and
6, and represented by Cross Sections 3 through 10, Figures 15 through 22, respectively.
Fresh scars from block falls mark the sea cliff and upper bluff below 20 of the 28
residences in the reach, from 245 to 309 Pacific Avenue, from 327 to 337 Pacific Avenue,
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