Palynology of Pinedale Sediments, Devlins Park, Boulder County, Colorado

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Abstract
A core of varved lake sediments from Devlins Park, Front Range, Colorado, has yielded a radiocarbon-dated pollen record of environments during the last major advance of Pinedale ice. The downstream end of Devlins Park was dammed by Pinedale ice from 22,400-12,180 BP, creating the lake. The pollen diagram is dominated by Artemisia (40-60%) and Pinus (10-25%). Gramineae, Chenopodiaceae-Amaranthaceae, Compositae, Juniperus and Picea pollen are also constantly present at low percentages. Arboreal pollen percentages are low, ranging from 13-30%. Pollen concentration varies from 6000-40,000 grains cm-2 of wet sediment. Modern pollen rain from a nearby wet depression is very different from the core pollen spectra, with greater percentages of Pinus (70%) and Picea (6%) pollen, less Artemisia (7%) pollen, and pollen concentration of 106,000 grains cm-2. Scattered pollen grains of tundra plants, low pine pollen percentages, and low pollen concentrations indicate that Devlins Park was above tree line during Pinedale time. Picea/Pinus ratios suggest that tree line averaged about 500 m lower than at present.

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