A Pollen Profile from Woden Bog in North‐Central Iowa

Vegetational and environmental changes are deduced from a pollen diagram at a site located in present—day prairie grassland. Three pollen assemblage zones were delineated by analysis of the 10—m core starting with a spruce—fir assemblage which began about 12,000 years ago and was replaced by a deciduous forest assemblage about 10,500 years ago. During the period 9,000—7,500 years ago there was a progressive increase in nonarboreal pollens. At the end of this time, the prairie flora is believed to have been well established.