Abstract
The Rocky Point Member of the Peedee Formation (Cretaceous of North Carolina), exposed in quarries near Castle Hayne and Rocky Point, was named informally by Swift and Heron and herein is designated formally as a stratigraphic unit. In the type section, it consists of 10.5 m of pelecypod biosparrudite, unconsolidated quartz arenite, and an alteration of the two. The invertebrate macrofauna and microfauna indicate a Maestrichtian (= Navarro) age.
Confusion has arisen over the problem of real or supposed mechanical mixing of faunas between Upper Cretaceous units and the overlying Castle Hayne Formation of Eocene age. The Rocky Point Member is overlain with spectacular unconformity by a hard phosphate-pebble conglomerate which is the basal bed of the Castle Hayne Formation. This conglomerate has some reworked Cretaceous fossils together with Eocene fossils, as first indicated by Tuomey. The underlying Rocky Point Member has more resemblance to some Castle Hayne outcrops in North Carolina than it does to the typical glauconitic, argillaceous sands of the Peedee Formation. It is probably because of this fact that the idea of mechanical mixing of faunas, moderately true for the basal Castle Hayne conglomerate, has been extended incorrectly to include the Rocky Point Member. The presence of unworn, delicate specimens of the echinoid, Hardouinia and a spiny Exogyra mitigate against any notable amount of abrasion. This, coupled with the presence of exclusively Cretaceous foraminiferal species and the absence of any exclusively Eocene species, mokes the mechanical-mixing theory inapplicable to the Rocky Point Member. The Cretaceous-Tertiary boundary is the conspicuous unconformity between the Castle Hayne Formation and the Rocky Point Member of the Peedee Formation in southeastern North Carolina.
