LATE QUATERNARY ENVIRONMENTS, DENALI-NATIONAL-PARK AND PRESERVE, ALASKA

Late Quaternary pollen, plant macrofossils, and insect fossils were st udied from sites along three rivers in the foothills north of the Alas ka Range in Denali National Park and Preserve. The aim was to carry ou t a reconaissance of late Quaternary organic sediments in the region, emphasizing the mid-Wisconsin, or Boutellier interstadial interval. Sa mples of probable early- to mid-Boutellier age (ca. 60 000 to 40 000 B .P.) from Unit 2 at the Toklat High Bluffs site indicate open boreal w oodland with dense alder shrub vegetation. Organic Unit 1 at the Forak er River Slump site indicates open taiga with shrubs of probable Boute llier age. Fossil evidence from the youngest horizon in this unit indi cates graminoid tundra environments, marking the transition from inter stadial to late Wisconsin glacial environments. Early Holocene samples from the Foraker exposures suggest birch shrub tundra; coniferous for est apparently became established only after 6500 B.P. Local variation s in forest composition at the Foraker and Sushana sites were probably the result of disturbances, such as fire.