A stratigraphically conformable dinoflagellate zonation ranging in age from Vraconian Albian to earliest Oxfordian-middle Callovian is distributed through 875 m of section recovered at Deep Sea Drilling Project Site 534A. The Cretaceous interval is the most fossiliferous studied to date in the paleobathymetrically deep western North Atlantic, and correlates well with five other sites. The Cretaceous-Jurassic boundary, considered to be conformable, is in nannofossil ooze just below the first red intercalated layers but above the major lithology of the Jurassic Cat Gap Formation. Jurassic assemblages are not as well preserved, but provide stratigraphically useful species.
Blackish sediment is present intermittently throughout the investigated section at Site 534A; its origin is considered to be related to sedimentation rates.