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Show mountain resources. The limnomobile strategy occurs where valley marsh ecosystems are too small to provide storable surpluses sufficient for overwintering, forcing people to adopt a mobile strategy in which they either move themselves to a series of foraging areas, transport a variety of resources to a central area, or, more likely, both. In this strategy, mountain resources, located in both mid- slope and alpine areas, are important components of the annual round as people move through a series of foraging localities. However, unless one or more upland resources, such as pine nuts, is particularly productive in any given year, sites in or near valley marshes most often continue to be the focus of overwintering stays. This is particularly true where large game animals congregate around the fringes of the marsh during the winter months. Transport of bulk resources is relatively expensive, and the preferred alternative ( that is, the most productive) is usually the sedentary strategy. As a result, change in the size and/ or productivity of Great Basin marsh systems had a major impact on prehistoric peoples. The degree of sensitivity to climatic change often correlates with the size of the marsh, with smaller spring and stream- fed marsh systems subject to more variance in terms of both size and productivity. Large marsh systems at the terminus of major rivers are most affected by extreme climatic change because of the differential morphology of valley bottoms and mountain slopes. In response to small scale climatic change, these large marsh systems move back and forth across the relatively flat valley floors left by Pleistocene lakes, but remain essentially intact. While there is often a short period of recovery, modest increases or decreases in available water do not greatly affect their overall utility for foraging peoples. A marked change in available water, however, can dramatically affect the size of many large marsh systems. This is particularly true when increases in water volume are sufficient to flood the flat valley floors. When this occurs, the configuration of lake- edge marshes changes from broad circumscribed areas at the deltas of major rivers to narrow, linear habitats, increasingly subject to wave impacts, along the steeper valley margins. Even where limited amounts of marsh vegetation occur along these linear patches, the advantage that large marsh systems give, in terms of reduced transport costs, is lost. Due to the link between adaptive strategies and large valley marsh systems, major changes in the size of Great Basin lakes over the past 12,000 14C years have had a dramatic effect on the course of Great Basin prehistory. The late Quaternary lake sequence is defined in more detail by others in this symposium ( see especially Oviatt, Negrini, Menking and Lowenstein), but briefly, there are four prolonged periods where the relationship between Basin peoples and lakes is most obvious. The first of these is the Younger Dryas, a period between ~ 11,200- 10,100 14C years ago when Great Basin lakes covered many of the valley floors. This period, commonly known as the Paleoindian period, is characterized by large fluted and stemmed points most often found around the margins of these late Pleistocene lakes ( Willig et al. 1998). What little is known about the adaptive strategy these people followed is based on inference, as virtually no buried sites containing substantive subsistence data have been recovered. Due to the presence of numerous sites along the lake margins, these people presumably focused on lake margin habitats, but what exactly they were doing there is unclear. If Younger Dryas climates in the Great Basin were as volatile as those defined elsewhere in the world ( e. g., Mayewski et al. 1993), population levels were probably maintained at relatively low levels as Paleoindian groups were repeatedly subject to periods of stress. Following the Younger Dryas, Great Basin lakes regressed to levels approaching their modern levels and large stable marsh systems appeared along the eastern and western margins of the basin. The sedentary adaptive strategy, defined above, appeared almost immediately in some areas, and |
