Lake records of Paleoindian and Archaic environments of the Northern Plains: The “park oasis” hypothesis

Catherine H. Yansa

    Fossil pollen and other proxies from lake sediments are used to reconstruct past dynamics in vegetation, climate and local availability of potable water for the Northeastern Plains, thereby providing a landscape context to re-assess local Paleoindian and Early Archaic subsistence strategies and settlement patterns. Presented are pollen and plant macrofossil data from two lakes in North Dakota and discussion of these results in the context of published paleoenvironmental and archaeological data for the region. Aridity has characterized the regional climate since deglaciation. From 12,000 to 10,000 14C yr BP, this aridity was counter-balanced by glacial meltwater saturating much of the landscape, which supported a vegetation of white spruce parkland. The regional water table lowered after 10,000 14C yr BP. As some lakes went dry or became saline others received ground-water input, thereby creating scattered “oases” in a deciduous parkland, which would have attracted prehistoric people and game alike. Grassland became widespread by 9,000 14C yr BP. Alternating arid and moist intervals characterized the mid-Holocene Altithermal, but some oases existed in the region. This paper supports the hypothesis proposed by some archaeologists for the persistence of human occupation of the Northern Plains during the Altithermal except, perhaps, during the severest droughts.