The following descriptions apply to the map by Dibblee (1999).
af artificial fill or cut and fill (Dibblee, 1999).
Qa alluvium, mostly loamy clay of valleys and flood plains (Dibblee, 1999).
Qae alluvium, similar to Qa but slightly elevated and locally dissected (Dibblee, 1999).
Qds loose dune and drift sand (Dibblee, 1999).
Ql Lomita Marl - shallow marine sediments, gray-white marl and calcareous fine-grained sandstone, gray siltstone (Dibblee, 1999).
Qls landslide debris - debris mostly of Monterey shale (Dibblee, 1999).
Qoa Older surficial sediments - older alluvium, non-marine terrace cover, sandy loam and loamy clay (Dibblee, 1999).
Qos Older surficial sediments - older, stabilized dune and drift sand, mostly unconsolidated fine-grained sand (Dibblee, 1999).
Qs beach sediments, ranging from sand to cobble-boulder gravel (Dibblee, 1999).
Qsp San Pedro Sand - shallow marine sediments, light gray to reddish-tan sand and pebble gravel, pebbles derived mostly from Miocene hard siliceous shale and limestone detritus; massive to locally cross-bedded (Dibblee, 1999).
Qtp Timms Point Silt - shallow marine sediments, yellowish-gray to gray sandy siltstone (Dibblee, 1999).
sc Catalina Schist - quartz-sericite-schist, quartz-chlorite-schist, glaucophane blueschist, dark bluish-gray , weathered to rust brown, foliated and contorted; contains white quartz veins, thick chert beds, and rare small masses of metagabbro (Dibblee, 1999).
Tb Basalt - submarine flows, pillowed flows, and breccias in the lower part of the Altamira Shale, black, fine-grained basalt to mafic andesite, age approximately 14.5-15.5 mybp (Conrad and Ehlig, 1983).
Tfr Fernando Formation - soft gray siltstone-claystone, locally glauconitic, early Pliocene age (Dibblee, 1999).
Tmad Diatomite in San Pedro area - diatomite and diatomaceous shale similar to the Valmonte Diatomite but assigned by Dibblee (1999) to the upper part of the Altamira Shale.
Tmat Altamira Shale, lower part - mostly light grey shale and mudstone with with tuffaceous and dolomitic strata throughout, contains flows and intrusions of basaltic rocks (Dibblee, 1999).
Tmf Point Fermin Sandstone member of the Altamira Shale - light-grey, bedded, indurated sandstone with abundant grains, pebbles, and cobbles of blueschist (Dibblee, 1999).
Tma Altamira Shale, upper part - white-weathering, thin-bedded siliceous and phosphatic shale with interbeds of siltstone and limestone, locally organic and diatomaceous (Conrad and Ehlig, 1983).
Tmg Malaga Mudstone - described as massive radiolarian mudstone or fine-grained siltstone and assigned as the upper member of the Monterey Formation by Woodring, Branlette, and Kew (1946); described as light gray sandstone and dark gray-brown mudstone with diatomaceous strata and limestone concretions and assigned to formation rank by Dibblee (1999).
Tmv Valmonte Diatomite - diatomite, diatomaceous shale, diatomaceous mudstone. According to Woodring, Bramlette, and Kew (1946) dry diatomite and diatomaceous shale are white but are almost black when wet.
Tso San Onofre Breccia - clastic rocks exposed at the base of Altamira Shale at Bluff Cove only, unsorted, subangular clasts, up to 0.5 m in size, probable landslide deposits (Dibblee, 1999).
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