DEPOSITIONAL CIRCUMSTANCES OF THREE PALEOINDIAN SITES ALONG LIMA RESERVOIR, MONTANA

Wave action along the Lima Reservoir in Centennial Valley, Montana has exposed three adjacent Paleoindian sites along the north shore cutbank. While these sites date to the same period and are near each other (within 1.5 miles), they possess markedly different geologic contexts. The westernmost site, 24BE43, is a surface scatter resting on an old soil with a very well-developed Btk horizon. The eastern site, 24BE52, is also a surface manifestation but it sits on a very thin soil capping what appear to be eroded lacustrine sediments. The center site, 24BE46, contains a likely Paleoindian subsurface component and younger surface cultural material. Using optically stimulated luminescence (OSL) dating, stratigraphic mapping, and sediment analysis, we determine the likely geomorphic sequence of events for these three sites and attempt to explain why they differ. Identifying which landforms and sediment types contain intact buried cultural material among these sites may help determine what other areas in Centennial Valley have good potential to contain subsurface archaeological deposits.