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Eocene lithofacies and depositional history in a portion of the Del Mar Quadrangle, San Diego County, California
Ashton, Donald Alan
Abbott, Patrick L.
Miller, Richard H.
Exposed Middle Eocene strata in the Del Mar area from Soledad Valley to Solana Beach and inland nine kilometers in northern San Diego County, include the Delmar, Torrey, Ardath, Scripps, Friars, Stadium, and Rose Canyon Formations. Depositional interpretations from lithofacies and correlation with middle Eocene sea level fluctuations indicate a transgressive event beginning with fan-delta, then supratidal-intertidal lagoon, subtidal lagoon, nearshore and shelf systems that later were incised by an inner- to mid-fan tributary submarine channel to the Torrey Submarine Canyon. Lithologic interpretations from 25 stratigraphic columns indicate a major onlapping sequence with one minor offlapping sequence during the middle Eocene. A stratigraphic sequence inland through Del Mar begins with fluvially influenced supratidal-intertidal lagoonal mud flats, followed by subtidal lagoonal channels and bars, and nearshore sandstones and shelf mudstones. A brief regression resulted in minor off-lapping of depositional environments. A final transgression occurred and then depositional environments prograded seaward. An onlapping stratigraphic sequence inland through the Torrey Pines Park also begins with supratidal-intertidal mud flats and subtidal lagoonal channels, but is unconformably truncated by the erosional base of an inner- to mid-fan tributary submarine canyon which became inactive as the shore moved farther east. Nearshore sandstone beds intercalated in shelf mudstone layers record a minor offlapping sequence. Progradational nearshore sandstone beds finish the sequence.
Donald Ashton used the United State Geological Survey 7.5-minute Del Mar Topographical Quadrangle as his base map. [Plate 1]. 1:24,000
San Diego State University
Master of Science (M.S.) San Diego State University, 1987
Del Mar Formation
Torrey Pines State Reserve
North America – United States – California – San Diego County – Del Mar Quadrangle
Northlimit = 32.983611 Westlimit = -117.265278 Eastlimit = -117.167222 Southlimit = 32.902778
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