A 272 cm sediment core from Siesta Lake (2430 m), Yosemite National Park, California was collected and analyzed for pollen, macroscopic charcoal, magnetic susceptibility and macrofossils. The age of the resulting record is 11,700 years. Five main pollen and charcoal zones were identified. Zone SL-1 (11,700-10,940 yr B.P.) is the zone for which no pollen was recovered. Preservation was extremely poor due to the possible dry phase of the lake, though vegetation probably existed in the basin at this time. Low charcoal values are recorded which supports the theory that vegetation and pollen were present in the basin, but not preserved due to oxidation. Magnetic susceptibility values are extremely high in this zone, possibly due to large amounts of glacial sand in the sediment. Zone SL-2 (10,940-9050 yr B.P.) is interpreted as dry with open forest structure as indicated by the high values of Artemisia and other indicative pollen types. The extremely drought conditions may have caused Siesta Lake to dry up at approximatelly 10,800 yr B.P. (222-223 cm). This is represented by oxidized sediments and very little pollen preservation below this level. Small charcoal peaks indicate a period of low fire activity. Zone SL-3 (9050-5650 yr B.P.) reflects a warming trend that cannot be strongly correlated to the Altithermal due to only approximately 1500 years of overlap of calendar ages. Poor correlation to the Altithermal is attributed to little similarity with Great Basin climate. Forest structure remained open with little fire activity as recorded by sedimentary charcoal. Zone SL-4 covers from 5650 yr B.P. to 2420 yr B.P. Large peaks in charcoal characterize this zone. The climate during this time was cooler and wetter, and the forest structure became dense and closed. The cooler/wetter conditions are attributed to the development of El Nino conditions around 5000 yr B.P. The late Holocene zone (SL-5) spans from 2430 yr B.P. to present. The pollen in this zone reflects a warm and dry environment with dense forest and closed canopy although the pollen data can alternately be interpreted to indicate Neoglacial cooling. This zone also contains the largest charcoal peaks, that when analyzed with the magnetic susceptibility data indicate a record of local fire. Anamalous peaks of charcoal occur in sub-zone SL-5b which may be caused by incomplete mechanical breakage or an increase of the density of the forest within the past ca. 1400 yr B.P.