Three late‐glacial pollen and plant Macrofossil assemblages from Iowa

Abstract Late‐glacial pollen and plant macrofossil assemblages from the Brayton gravel pit in southwestern Iowa, Nichols silts in southeastern Iowa, and Summer Bog in northeastern Iowa indicate that a spruce‐larch forest was present between about 12,500 and 11,500 radiocarbon years before present (RCYBP). Some forest openings probably existed at Brayton and during the lower zone recognized at Sumner Bog, but not at Nichols. All Sites contain pollen of thermophilous species; macrofossils of Quercus rubra (northern red oak) and Corylus cornuta (beaked hazel) at Brayton and of Acer negundo (box elder) at Nichols indicate that some thermophilous plants were locally present. Fir trees were present in small numbers, but pine was absent.