Deadman Island in San Pedro Harbor was the type locality for the upper and lower San Pedro Series until its destruction in 1928 during enlargement of the Long Beach/San Pedro Harbors. Early work on the Island showed eight fossiliferous horizons (zones). Zones 1 to 6 were attributed to the Santa Barbara Formation and later to the Timms Point Silt. Zone 1 contains Calyptogena gibbera Crickmay, which is known only from Deadman Island, the Niguel Formation, and the Towsley Formation. The Niguel and Towsley formations are both late Pliocene in age, suggesting a similar age for Zone 1 on Deadman Island. Fossils from Zones 2-6 suggest deposition in water temperatures cooler than present, and at water depths between 50 and 100 m. Zone 5 contains the coolest and deepest fauna. The fauna and sediments from Zones 2-6 suggest correlation with the Timms Point Formation of middle Pleistocene age.

Reworking seems to be a major problem in the upper zones (7 and 8) on Deadman Island. Fossils from Zone 7 (lower San Pedro series) suggest water temperatures similar to today, and deposition in water between 25 and 30 m deep, possibly deeper, on an open coast. Both northern and southern extra-limital taxa are present, but it is not clear which are autochthonous or allochthonous. Amino acid data suggest the southern extra-limital taxa are autochthonous, and correlate with oxygen-isotope Stage 5e. Fossils from Zone 8 (upper San Pedro series) also suggest water temperatures similar to today, and deposition in water depths between 5 and 30 m on an open coast. Both northern and southern extra-limital taxa are again present. The amino acid data suggest the southern extra-limital taxa are probably reworked and zone 8 correlates with oxygen-isotope Stage 5a.