The Gray Fossil Site (GFS) includes multiple karst sub-basins that are filled with lacustrine sediments. Early paleontologic work on one of the sub-basins (GFS–2) indicates a late Miocene/early Pliocene age based on an assemblage of well-preserved vertebrate fossils. However, detailed palynological analysis of the 38.7 m deep GFS–1 core recovered from another sub-basin indicates an older age. The presence of Caryapollenites imparalis, C. inelegans and C. prodromus association suggests a Paleocene to Eocene age for the GFS–1 core section. This age is also supported by the absence of pollen of the Poaceae, the grass family that is not commonly present until the Neogene. Age constraints from palynologic data suggest that the GFS has a more complex basin-fill history than previously suspected, and that multiple depo-centers within the basin may have been periodically active through the Cenozoic. Palynofacies analysis of the GFS–1 core indicates that phytoclasts and opaques are the most abundant organic constituents and have diluted both the palynomorph population and amorphous organic matter. Two possible scenarios can account for this observation: 1) an oxidizing depositional paleoenvironment; and 2) a localized high flux of charcoal following wildfires and subsequent increased runoff.