Palynological analysis of the Lower Tertiary section at Site 959 (ODP Leg 159) yielded a rich palynomorph assemblage of abundant pollen (representing gymnospermous evergreen, coastal palm and swamp/mangrove-associated vegetation along with conifer saccates), pteridophytic and lycophytic spores, chlorococcolean algae, and fungal spores. This passive margin interval was characterized by biosiliceous sedimentation in a deep bathyal ( approximately 3100 m b.s.f.), sub-carbonate compensation depth environment. The distribution and abundance of land-derived organic matter from West Africa, in addition to shallow-water foraminifera, acritarchs, and dinoflagellate cysts at this deep offshore depositional site, were primarily controlled by such factors as continental runoff, marine current transport, seasonal upwelling events, sea-floor topography, and diagenetic degradation. The total palynofloral assemblage is interpreted as representing a highly diverse, moderate to dense canopied, broad-leaved lowland rain forest fringing a coastal fresh/brackish-water vegetation community. For much of the Early Tertiary, the vegetation prevailed under a tropical climate analogous to conditions in present-day Indo-Malaysia, Borneo, and West Africa (Gabon, Cameroon, Nigeria). Five major continental ecological complexes and three paleoclimatic events were distinguished from the palynofloral assemblage. These ecological successions reflected drier, Late Paleocene temperate-subtropical conditions which gradually shifted to warmer, more humid tropical conditions (encouraging high pollen speciation) during the Early Eocene. Plant communities requiring high humidity and low evaporation rates culminated in dense forest growth during the Middle Eocene maximum tropical expansion. Beginning in the latest Middle Eocene and continuing into the earliest Oligocene, the paleovegetation communities indicated fluctuating climatic changes culminating in cooler, drier subtropical-temperate conditions. Similar ecological and climatic events can be deciphered from the marine phytoplankton assemblages. The marine realm experienced changing sea-surface temperatures associated with the Early Cenozoic integration of the Cote d'Ivoire-Ghana Marginal Ridge into the larger Atlantic system and the closure of the eastern Tethys Sea.