The biostratigraphic and chronostratigraphic position of the Comfort Member of the Castle Hayne Formation has been the subject of much debate. At the Martin-Marietta Quarry at Castle Hayne, New Hanover County, North Carolina, the planktic foraminifers indicate an assignment within an interval of the uppermost Turborotalia frontosa Zone to the Turborotalia pomeroli Zone. The calcareous nannofossils indicate an assignment to the middle part of the Chiasmolithus solitus Zone. The dinocyst data indicate placement in the upper part of the Kisselovia coleothrypta Zone of Costa and Downie. These zonal units are considered to be within the middle Eocene of international usage, and, on the basis of the time scale used in this paper, the Chiasmolithus solitus Zone represents a time interval of 42.1 to 45.4 megaannums (Ma). This differs significantly from a Rb/Sr glauconite date of 34.8 ± 1.0 Ma previously obtained at the same locality.