Late Pleistocene Pollen and Plant Macrofossils from a Buried Wetland Deposit in the Platte River Valley, South-Central Nebraska

Abstract

We present a pollen and plant macrofossil record from a 47-cm-thick deposit that dates from approximately 23,400 to 22,600 cal yr BP. The site is in the Platte River valley near Kearney, Nebraska. The organic-rich deposit is buried by 6 meters of Peoria loess and 3 meters of loess and loess-derived alluvium. Picea (spruce) needles and small wood fragments were the most visually prominent material in all macrofossil samples. We also identified Carex (sedge) and Pilea fontana (clearweed) seeds in all samples. We recorded 28 pollen types overall, mostly Picea and Cyperaceae (sedges). Minor amounts of Pinus (pine), Salix (willow), and Cupressaceae (juniper family) as well as non-arboreal pollen types, and spores such as Poaceae (<37 μm; grass), Aster type (composite family), Artemisia (composite family), and Polypodiaceae (ferns), are present. Clumps of immature pollen grains of Picea, Salix, Cyperaceae, and Poaceae (<37 μm) occur. Picea stomata were also recorded. We suggest, based on the pollen and macrofossil evidence, that a spruce forest with interspersed sedge wetlands existed in the Kearney area about 23,000 years ago. The Kearney site is one of the few last glacial maximum pollen and plant macrofossil localities reported from the central Great Plains.