Sierra foothills mélange of Duffield and Sharp [1975]
Sierra foothills mélange of Duffield and Sharp [1975]
Late Jurassic, Oxfordian to Kimmeridgian
Sedimentary-matrix mélange, including bodies of gabbro, marble/limestone, andesite, serpentinite, and chert. Grades northward near Cosumnes River into conglomerate and olistostrome, including andesite clasts probably derived from underlying Logtown Ridge Formation. Conglomerate there includes granitic clasts and is interfingered with Mariposa Formation (unit CMMS). Previously mapped in part as Mariposa, Cosumnes, and Calaveras formations (Clark, 1964). Previously thought to depositionally underlie the Logtown Ridge Formation, but probably lateral stratigraphic equivalent to intertongued Mariposa Formation.