The Point Loma Formation, the intermediate part of the Rosario Group, crops out along the sea cliffs on the west side of the Point Loma Peninsula, and in the La Jolla sea cliffs from Bird Rock to La Jolla Shores Beach. At its type locality at the tip of Point Loma, it has an exposed thickness of 83 meters. The rocks there are interbedded finegrained dusky-yellow sandstone and olive-gray clay shale that occur in graded beds about 30 centimeters (cm) thick. Scuba-diving observations 1860 m offshore from the type locality show that ledgy pavement-like sandstone, similar to that in the lower half of the exposed section, continues to a depth of at least 37m (Turner et al., 1968, p. 8). With a shoreline dip of 6 degrees east, it is postulated that 190 m of section may be added below low-tide level to the observed thickness of the formation. This submarine information, combined with interpolation from well logs, suggests that the total thickness of the Point Loma Formation at its type locality is about 300 m. Fossil Foraminifera and calcareous nannoplankton indicate a Late Cretaceous age for the Point Loma Formation (Sliter, 1968; Bukry and Kennedy, 1969). Foraminifera from near the base of the formation at Carlsbad are middle to upper Campanian in age, whereas those from the uppermost beds are lower Maestrichtian in age (Sliter, 1968). The exposed part of the Point Loma Formation correlates with the Williams Formation and the upper part of the Ladd Formation in the Santa Ana Mountains (Popenoe et al., 1960) and with the middle part of Beal's (1924) Forrnacion Rosario in northern Baja California.

Source - Geology of the eastern San Diego metropolitan area, California (Del Mar, La Jolla, Point Loma, La Mesa, Poway, and SW 1/4 Escondido quadrangles), 1975, California Div. Mines and Geol. Bull. 200, Section A, by Michael P. Kennedy

References

Beat, C.H., 1924, lnforme sobre la exploracion geologica de la Baja California: Boletin Petroleo, v. 17, p. 417-473.
Bukry, David, and Kennedy, M.P., 1969, Cretaceous and Eocene coccoliths at San Diego, California, in Short contributions to California geology: California Division of Mines and Geology Special Report 100, p. 33-43.
Popenoe, W.P., Imlay, R.W., and Murphy, M.A., 1960, Correlation of the Cretaceous formations of the Pacific coast (United States and northwestern Mexico): Geol. Soc. America Bull., V. 71, p. 1491-1540.
Slitter, W.V., 1968, Upper Cretaceous Foraminifera from southern California and northwestern Baja California, Mexico: The University of Kansas Pubs., Art. 7, Ser. no. 49, p. 141.
Turner, H.C., Ebert, E.E., and Given, R.R., 1968, The Marine environment offshore from Point Loma, San Diego County: California Department of Fish and Game, Fish Bull. 140.