(Table 1) Microfossil events at DSDP Leg 81 Holes

Leg 81 of the DSDP drilled four sites in a small area on the southwest flank of the Rockall Plateau. The biostratigraphy of the cores is based on six groups of microfossils: calcareous nannofossils, diatoms, dinoflagellates, planktonic foraminifers, radiolarians, and silicoflagellates. A good magnetostratigraphic record covering the interval from the top of the Brunhes to the Gauss/Gilbert boundary was obtained from one of the sites. Since magnetostratigraphy was not available for the older part of the section, it was not possible to estimate whether biostratigraphic indications in sediments older than 3.4 m.y. are diachronous or synchronous from low to high latitudes.
The biostratigraphic resolution is generally low for any single group, but higher resolution can be attained by using all available microfossil groups. A composite list of biostratigraphic events (mainly Neogene) is presented.