Between Quartz Hill and Fall Creek Mountain, California, the Shoo Fly Complex includes the Poison Canyon and Red Hill formations. Field, biostratigraphic, and U-Pb zircon data indicate that both formations are most likely post-Cambrian and pre-Middle Devonian in age. Medium-grained and pebbly sandstone in both formations was deposited in submarine-fan environments by subaqueous sediment gravity flows laden with continentally derived detritus. The source of terrigenous detritus in the Poison Canyon and Red Hill formations included rocks that contained zircons as old as ∼2.09 b.y. The depositional basin in which the Poison Canyon and Red Hill formations accumulated was floored by oceanic lithosphere and was close enough to some continental landmass to have received sand-sized detritus derived from it. The continental landmass may have been located in western North America, but there is nothing in the data presented here that precludes the possibility that it was located on some foreign continent.