Monte de Oro Formation
Monte de Oro Formation
Late Jurassic, Oxfordian to Kimmeridgian
Slate, slightly sheared sandstone and siltstone, and minor conglomerate. Contains plant and mollusk fossils. Probable nearshore deposition. Overlies the Oregon City Formation. Imlay (1961) reports fossils that are probably late Oxfordian to early Kimmeridgian.