The Blake Nose area (western North Atlantic; approximately 350 km east of Florida, USA) represents the longest currently available single-locality record of diatom evolution, spanning approximately 30 million years of the early Cenozoic Era.

This study provides a detailed taxonomic account of the diatom assemblages found in the lower Paleocene through upper Eocene deep-sea sediments recovered by Ocean Drilling Program Leg 171B from the Blake Nose. The main study sites are Holes 1050A, 1050C and 1051A. For comparative purposes, materials from other deep-sea holes and onshore sites are included as well.

A total of 137 taxa representing 60 genera are examined using scanning electron and/or light microscopy. Two new combinations are performed (Psammodiscus praenitidus (Fenner) J. Witkowski, n. comb. and Sheshu­kovia castellifera (Grunow) J. Witkowski, n. comb.), and ten species are proposed as new (Brightwellia plana J. Witkowski, n. sp.; Detonia wadeae J. Witkowski, n. sp.; Distephanosira gleichiae J. Witkowski, n. sp.; Euodiella beatae J. Witkowski, n. sp.; Hemiaulus curvatuloides J. Witkowski, n. sp.; Hemiaulus imperator J. Witkowski, n. sp.; Hemiaulus jordani J. Witkowski, n. sp.; Hemiaulus oreshkinae J. Witkowski, n. sp.; Medlinia? subtriangularis J. Witkowski & P.A. Sims, n. sp.; and Triceratium harwoodii J. Witkowski, n. sp.).

Emphasis in this study in on stratigraphic and geographic distribution of the diatom taxa encountered in the Blake Nose cores, and on documenting their morphological variability.

The overall aim of this work is to provide a reference for future biostratigraphic and paleoceanographic studies involving early Paleogene marine diatoms.