A HOLOCENE PALEOCLIMATIC AND ENVIRONMENTAL RECORD FROM STONEMAN LAKE, ARIZONA

Stoneman Lake, Coconino County, Arizona, occupies a 600,000-yr-old caldera on the southern edge of the Colorado Plateau. Changes in fossil diatom floras, pollen profiles, macrofossil remains, and geological characteristics of a sediment core show changing aquatic and terrestrial environments over the past 9000 yr. Cool temperatures and greater effective precipitation than at present are indicated during the early Holocene, prior to 8500 yr B. P. A warmer and drier period followed (8000 and 2000 yr B. P.) during which time a marsh-like environment developed within the caldera, and xeric plant communities were established along the southern Colorado Plateau. Modern plant communities have existed in this region for the past 6000 yr, although lake conditions have fluctuated. (C) 1994 University of Washington.