Pleistocene Vegetational Studies in the Whitewater Basin, Southeastern Indiana

The Illinoian and Wisconsin Pleistocene stratigraphy of the Whitewater basin, southeastern Indiana is summarized. Analyses are of the vegetation preserved in an Illinoian interstadial deposit, the Sangamon soil, and an early Wisconsin interstadial deposit. The pollen diagrams show a vegetational succession during Sangamon time from conifers (mostly pine) to hardwoods, with a final reversion to a coniferous boreal forest of spruce, fir, and pine at the beginning of the Wisconsin Stage. The Sangamon hardwood period was apparently warmer and drier than the postglacial hypsithermal interval in the region. Spruce wood and mosses were found at the upper surface of the Sangamon soil, buried by glacial rock flour and the earliest Wisconsin till; these, together with pollen data, provide a partial record of the flora extant at the end of the Sangamon interglacial, or the beginning of the Wisconsin. Pollen and mosses from Illinoian and Wisconsin interstadial calcareous deposits indicate that these intervals were probably short and cool throughout. Comparison of the palynological results obtained in this study is made with the few other Sangamon and interstadial vegetational analyses which are known. One of these earlier vegetational studies by Voss (1933, 1939), on presumed Sangamon peat from central Illinois, is re-evaluated on the basis of later geologic evidence and is now considered to represent an early Wisconsin interstadial deposit.