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 City of Solana Beach
Section 3
Shoreline and Coastal Bluff Management Strategies Draft MEIR
Environmental Impact Analyses
seacliff and forms the modern wave-cut platform, it consists of grayish-green sandy claystone
with resistant mollusk-bearing beds (Ostrea idraensis). It is gradationally overlain by the Torrey
Sandstone (Kennedy, 1975).
A relatively localized area of the Del Mar Formation (on the beach just west of 645 West Circle
Drive) contains brackish-water mollusks (Kennedy, 1975). Although they are relatively localized
in the Del Mar Formation, they were also observed in the overlying Torrey Sandstone (Kennedy,
1975) in Solana Beach and in the Del Mar Formation (south of Solana Beach) in Del Mar and
north San Diego. The areas in Solana Beach may be considered locally significant since they
are easily accessible to parking areas and beach access, but these assemblages also occur
elsewhere in the Solana Beach area and adjacent areas (Del Mar and San Diego).
Torrey Sandstone
The Torrey Sandstone of the La Jolla Group overlies the Delmar Formation and crops out
continuously along the shoreline of Solana Beach. The contact between the Torrey Sandstone
and the Delmar Formation is obscured by a seawall constructed at the bluff marking the
northern part of the Solana Beach coastline. It consists of white to light brown, medium- to
coarse-grained, massive to cross-bedded arkosic sandstone (Kennedy, 1975). Its age is
established as middle Eocene (49 to 47 million years old) by the interfingering relationship with
the overlying Ardath Shale observed in the area south of Torrey Pines State Park located south
of the project study area. The Torrey Sandstone forms the seacliff (lower) portion of the bluffs.
Ancient River Channel Fill
Several old (post-Eocene to pre-late Pleistocene, 120,000 years old or older) stream valleys,
cutting into the Torrey Sandstone bedrock and overlain by marine terrace deposits, are mapped
in the study area. The deposits, recognized as channel fill were mapped at Tide Park by Kuhn,
1977. According to Kuhn (1977), the embayment feature at Tide Park and Ocean Street is
approximately 110 feet in length and contains channel fill sediments primarily consisting of
arkosic sands and gravels. At present, these deposits are obscured by the (pre-1973) concrete-
bag seawall.
An ancient river channel observed at Fletcher Cove is filled with alluvial, colluvial/talus, and
marine estuary sediments. During the 1977 investigation by Kuhn, approximately 300 feet of
these deposits were exposed along the cliff and stabilized at their base by a concrete-gunite
seawall.
Two other river channels are located underlying Del Mar Shores Terrace and the Del Mar Beach
Club condominiums in the southern part of Solana Beach (Kuhn and Shepard, 1991).
Marine Terrace Deposits/Bay Point Formation
The marine terrace deposits unconformably overlying the Torrey Sandstone and the ancient
river channel fill are well exposed and continuous in the study area. They are deposited on a
Project No. 323530000
Page 3-8
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