Abstract
Discovery of the jaw of an American mastodont (Mammut americanum) and an unusual sedimentary profile in a cornfield in Warren County, Indiana, prompted a multidisciplinary study of the palaeoenvironment of the site. Wood taken from near the base of the deposit was dated at 15,540 ybp. Stratigraphic and textural analyses of the 2.3 m sedimentary profile reveal a series of inundation and desiccation events marked by polygonal fissures. Analysis of pollen from the sediment profile indicates that a boreal flora predominated during much of the time period represented by the profile. Pollen correlation indicates that the sedimentary record was truncated by unconformities around 10,000 ybp. Macrofossil analysis indicates a local environment that began as a forest dominated by white spruce and tamarack. Later inundation of the forest was indicated by the appearance of fish (Perca flavescens), meadow voles (Microtus pennsylvanicus), and submergent aquatic macrophytes (Myriopyllum exalbescens), Potamogeton pusillus, Ceratophyllum demersum, and Najas flexilis). The aquatic environment was interrupted by periods of exposure and desiccation as indicated by the disappearance of identifiable macrofossils and by the stratigraphy. The Shafer fossil assemblage is compared with other localities, and the taphonomy and palaeoenvironment of the mastodont are discussed.