High-resolution analysis of macroscopic charcoal in sediment cores from Little Lake was used to reconstruct the fire history of the last 9000 years. Variations in sediment magnetism were examined to detect changes in allochthonous sedimentation associated with past fire occurrence. Fire intervals from ca. 9000 to 6850 calendar years BP averaged 110 ± 20 years, when the climate was warmer and drier than today and xerophytic vegetation dominated. From ca. 6850 to 2750 calendar years BP the mean fire interval lengthened to 160 ± 20 years in conjunction with the onset of cool humid conditions. Fire-sensitive species, such as Thuja plicata Donn ex D. Don, Tsuga heterophylla (Raf.) Sarg., and Picea sitchensis (Bong.) Carr., increased in abundance. At ca. 4000 calendar years BP, increases in allochthonous sedimentation increased the delivery of secondary charcoal to the site. From ca. 2750 calendar years BP to present, the mean fire interval increased to 230 ± 30 years as cool humid conditions and mesophytic taxa prevailed. The Little Lake record suggests that fire frequency has varied continuously on millennial time scales as a result of climate change and the present-day fire regime has been present for no more than 1000 years.

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A 750-year fire history was reconstructed for the Central Plateau of Yellowstone National Park from the deep-water sediments of five lakes. The charcoal record from a large lake provided a chronology of regional fires. Data from four small lakes were used to study local and extralocal fires. The co-occurrence of abundant charcoal and high magnetic-susceptibility values at the same stratigraphic level was used as evidence of a local catchment fire, and a charcoal peak without high magnetic susceptibility was ascribed to an extralocal fire or a local fire without a related erosion event. The fire history was compared with the dendrochronologic fire record for the last 450 years, and the close agreement provided the justification to extend the chronology back in time. Large areas of the region burned in AD 1988, c. 1700, c. 1560, and c. 1440. From c. 1220 to 1440 and c. 1700 to 1987, intermediate to small areas burned. The near-absence of fires in the twentieth century prior to the large fires of 1988 is evident in the charcoal record.

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