26 Quaternary Geology and Paleoclimate (Posters)

Tuesday, 14 May 2002
1:30 PM - 5:30 PM

LATE QUATERNARY VEGETATION ASSOCIATED WITH THE KIRKLAND/LAKEVIEW ELEMENTARY SCHOOL MAMMOTH SITE, PUGET LOWLAND, WASHINGTON

Paper number: 26-7
Program: Technical Sessions
Time: 1:30 PM – 5:30 PM

Authors

Abstract

Pollen and plant macrofossil analysis of samples associated with the Kirkland/Lakeview Elementary School mammoth site (Barton and Kester, 2001) provide information on the composition of parkland and periglacial steppe vegetation during the late Olympia non-glacial period. The exposed section ranges lithologically from a basal lacustrine clayey silt to a fibrous peat capped by a fluvial sand. The pollen assemblage from sediments directly associated with the mammoth tusk dates to 16,540+/-80 14C yr B.P., (19,710 cal yr B.P.)[CAMS-70709]. Pollen from this assemblage is dominated by Cyperaceae (46%), Poaceae (14%), Artemisia (4%), Pinus cf. contorta (12%), Picea cf. engelmannii (2%), and Populus (4%). The nonarboreal component accounts for roughly 78% of the total pollen count. Reconstruction of the paleoenvironment, using both pollen and plant macrofossils associated with this assemblage, suggests an oligotrophic lacustrine setting surrounded by a fen margin with distal parkland vegetation. A modern analogue for this assemblage is the present-day subalpine parklands of the northern Rocky Mountains. This analysis suggests a cold, dry climate for the Puget lowlands during this time interval.