Backstripping analysis of the Bass River and Ancora boreholes from the New Jersey coastal plain (Ocean Drilling Project Leg 174AX) provides new Late Cretaceous sea‐level estimates and corroborates previously published Cenozoic sea‐level estimates. Compaction histories of all coastal plain boreholes were updated using porosity–depth relationships estimated from New Jersey coastal plain electric logs. The new porosity estimates are considerably lower than those previously calculated at the offshore Cost B‐2 well. Amplitudes and durations of sea‐level variations are comparable in sequences that are represented at multiple boreholes, suggesting that the resultant curves are an approximation of regional sea level. Both the amplitudes and durations of third‐order (0.5–5 Myr) cycles tend to decrease from the Late Cretaceous to the late Miocene. Third‐order sea‐level amplitudes in excess of 60 m are not observed. Long‐term (108–107 years) sea level was approximately constant at 30–80 m in the Late Cretaceous, rose to a maximum early Eocene value of approximately 100–140 m, and then fell through the Eocene and Oligocene.

Backstripping analysis of the Bass River and Ancora boreholes from the New Jersey Coastal Plain (Ocean Drilling Project Leg 174AX) provided new Late Cretaceous sea-level estimates and tested previously published Cenozoic sea-level estimates. Amplitudes calculated from all New Jersey boreholes were based on new porosity-depth relationships estimated from New Jersey Coastal Plain electric logs. In most cases, amplitudes and duration of sea level were comparable when sequences were represented at multiple borehole sites, suggesting that the resultant curves were an approximation of regional sea level. Sea-level amplitudes as great as 50 m were required by third-order Cretaceous sequences. Most amplitudes were probably closer to 20 to 40 m. Third-order (0.5-3 m.y.) sea-level changes of Paleocene and younger sequences were generally less than 30 m and were superimposed on a long-term (= 100 m.y. duration) sea-level fall from a maximum early Eocene value of approximately 100 to 140 m.

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