A 19,000-year vegetation and climate record for Bear Lake, Utah and Idaho

Pollen analysis of sediments from core BL96-2 at Bear Lake (42 degrees N, 111 degrees 20'W), located on the Utah-Idaho border in America's western cordillera, provides a record of regional vegetation changes from full glacial to the late Holocene. The reconstructed vegetation records are mostly independent of Bear Lake's hydrologic state and are therefore useful for identifying times when climate forcing contributed to lake changes. The Bear Lake pollen results indicate that significant changes in the Bear Lake vegetation occurred during the intervals 15,300-13,900, 12,000-10,000, 7500-6700, 6700-5300, 3800-3600, and 2200-1300 cal yr B.P. These intervals coincide with regional shifts in vegetation and climate, documented in pollen, isotope and biogeo-graphic records in the Basin and Range region, suggesting that large-scale climate was the primary forcing factor for these intervals of change. Maximum aridity and warmth is indicated from 12,000 to 7500 cal yr B.P., followed by intervals of generally more mesic and cool conditions, especially after 7500 cal yr B.P.