GEOMORPHOLOGICAL AND STRATIGRAPHIC PATTERNS OF MAMMOTH REMAINS IN WESTERN OKLAHOMA: THE CASE OF THE GRANDFIELD AND HELENA MAMMOTH LOCALITIES

The early peopling of the Americas and the causes of megafauna extinction are two topics highly debated in North American Quaternary science and archaeology. The apparent strong association between mammoth remains and humans is at the center of this debate. The research presented here addresses the geomorphological and stratigraphic contexts of mammoth site localities with mammoth remains in Western Oklahoma, most of which are associated with alluvial terraces. The study focuses in particular on the Grandfield and Helena localities, and their relations and similarities with other mammoth finding localities in the region, including those with association with human presence (e.g., Cooperton and Domebo). The mammoth remains of the Grandfield locality are situated on the highest terrace or a high-order stream. Soil development suggests a very old age, still unknown. The remains at the Helena locality are situated in the lowest terrace of a low-order stream. Soil development is less advanced. Although OSL dates on the bone-bearing sediments are pending, it is evident that a regional relative-age model can be elaborated. Thus far this study points to two main aspects of geoarchaeological significance: the location of the remains in relation to fluvial terrace level and the development of soils associated with the sedimentary deposits. These two aspects constitute the basic ways to establish a relative chronology that help decide which localities may have archaeological significance to be dated with absolute methods and properly excavated.