RECONSTRUCTION OF LAST GLACIAL MAXIMUM AVERAGE WINTER TEMPERATURES AND CHRONOLOGIC CORRELATION OF WISCONSINAN PALEOSOL DEVELOPMENT IN SOUTHWESTERN OHIO

The temperature history of paleosols developed in Late Wisconsinan glacial sediments of southwestern Ohio are poorly understood, but the presence of certain terrestrial gastropod species preserved within these paleosols may provide quantitative evidence for regional Last Glacial Maximum temperature conditions. Gastropods were collected at three sites—Oxford, Milford Cemetery, and Sharonville—to reconstruct this temperature history and correlate the chronology of paleosol development in the region. Over 1,100 individual shells, from 12 unique species, were identified to their lowest taxonomic order. The fossil assemblage is composed of primarily arctic and sub-arctic, cold-hardy species including: Columella alticola, Vertigo elatior, Vertigo hannai, Vertigo modesta, Vertigo modesta ultima, Vertigo oughtoni, and Pupilla moscurum. Other, more highly adaptable and less-distinctive species also found in the assemblage included: Discus whitneyi, Euconulus fulvus, Hendersonia occulta, Succineidae spp. and Vallonia gracilicosta. Succineidae spp. shells were used to radiocarbon date paleosol development at the three sites. The development of paleosols at the three sites occurred contemporaneously from around 24,000–22,000 calendar years before present, immediately after Wisconsinan ice reached its southernmost extent. The species found in this fossil assemblage are similar to those previously reported at Oxford and Milford Cemetery, as well as within a fossil assemblage from Two Creeks, Wisconsin, which represents another ice-proximal environment. Qualitatively, the closest modern analog environment would be a mid- to high-latitude boreal forest with some sparse open shrub land, similar to present-day northern Ontario. Mutual Climatic Range analysis was used to quantify the temperature conditions experienced in the region during the Last Glacial Maximum. Average winter temperatures during this time in southwestern Ohio were found to be 13–22°C colder than modern average winter temperatures. Gastropod-inferred Last Glacial Maximum average winter temperatures showed a high degree of similarity to both proxy records and simulations of average winter temperatures for the region.