Late-Glacial Vegetation and Climate Change in Western Oregon.
L.D. Grigg and C. Whitlock (1998),
Quaternary Research 49: 287-298.

Abstract:-and-nbsp; Pollen records from two sites in western Oregon provide information on late-glacial variations in vegetation and climate and on the extent and character of Younger Dryas cooling in the Pacific Northwest.-and-nbsp; A subalpine forest was present at Little Lake, central Coast Range, between 15,700 and 14,850 cal yr B.P.-and-nbsp; A warm period between 14,850 and 14,500 cal yr B.P. is suggested by an increase in Pseudotsuga pollen and charcoal.-and-nbsp; The recurrence of subalpine forest at 14,500 cal yr B.P. implies a return to cool conditions.-and-nbsp; Another warming trend is evidenced by the reestablishment of Pseudotsuga forest at 14,250 cal yr B.P.-and-nbsp; Increased haploxylon Pinus pollen between 12,400 and 11,000 cal yr B.P. indicates cooler winters than before.-and-nbsp; After 11,000 cal yr B.P. warm dry conditions are implied by the expansion of Pseudotsuga.-and-nbsp; A subalpine parkland occupied Gordon Lake, western Cascade Range, until 14,500 cal yr B.P., when it was replaced during a warming trend by a montane forest.-and-nbsp; A rise in Pinus pollen from 12,800 to 11,000 cal yr B.P. suggests increased summer aridity.-and-nbsp; Pseudotsuga dominated the vegetation after 11,000 cal yr B.P.-and-nbsp; Other records from the Pacific Northwest show an expansion of Pinus from ca. 13,000 to 11,000 cal yr B.P.-and-nbsp; This expansion may be a response either to submillennial climate changes of Younger Dryas age or to millennial-scale climatic variations.