The Folsom archaeological site is historically significant because it documented for the first time a direct association between people and Pleistocene fauna in North America. Stone projectile points, Folsom points, were found in association with bison bones representing 32 individuals, killed and processed by human hunters 10,500 years ago. First excavated in the 1920's, the site had not been studied using modern techniques of excavation, exploration, faunal analysis, or paleoecological analyses until recently. The purpose of this palynological study is to document the environmental history of the Folsom area to better understand the physical setting in which Paleoindians lived. A 217 cm-long pollen core from Bellisle Lake, located on Johnson Mesa 2 km west and 250 m above the archaeological site, provides a record of late Pleistocene and Holocene vegetation change from which a climatic history is inferred. During the Paleoindian occupation pollen assemblages document an open landscape dominated by sagebrush, asters and grasses; conifers were locally scattered or in distant stands. The early to middle Holocene portion of the core shows some stratigraphic mixing that has not yet been resolved, but generally is characterized by the presence of a less open landscape with mixed conifers around or near the lake. Iron mottling indicates fluctuating water levels beginning around 5000 B.P., but conifers remain dominant until about 4000 B.P. By the late Holocene, beginning about 600 B.P., pollen assemblages are marked by disturbance indicators including occasional cereal pollen indicating local cultivation before European contact. Preliminary interpretation of the climatic record is that the latest Pleistocene was cold and dry, but the early to middle Holocene was wet enough to support mixed conifer vegetation. The later middle Holocene was characterized by less reliable rainfall causing fluctuations in water level, and the latest Holocene provides evidence of land use rather than climate.

Key words: New Mexico, paleoclimate, Paleoindian, palynology, Quaternary, Southwestern paleoecology