Smear slides were prepared directly from raw samples and were examined using phase contrast and polarizing light microscopy in order to define the relative abundance of each nannofossil species. Selected sandy samples were processed by the settling method to concentrate the nannofossils.
The relative abundance of individual species and the total abundance for each sample" were tabulated for the range charts using a light microscope with a magnification of 1560×. The letters used on the range charts and the corresponding definitions are as follows:
V = very abundant; more than 10 specimens per field of view; A = abundant; 1 to 10 specimens per field of view;
C = common; 1 specimen per 2 to 10 fields of view; F = few; 1 specimen per 11 to 50 fields of view; and R = rare; 1 specimen per 51 to 200 fields of view.
Preservation of the calcareous nannofossil assemblage was recorded as follows:
G = good; individual specimens exhibit little or no dissolution or overgrowth; diagnostic characteristics are preserved and nearly all of the specimens can be identified;
M = moderate; individual specimens show evidence of dissolution or overgrowth; some specimens cannot be identified to the species level; and
P = poor; individual specimens exhibit considerable dissolution or overgrowth; many specimens cannot to identified to the species level.
Calcareous nannofossil species considered in this paper are listed in the Appendix, where they are arranged alphabetically by generic epithets. Bibliographic references for these taxa can be found in Perch-Nielsen (1985).