Prehistoric Human Occupation

Important Archaeological Sites of the eastern Snake River Plain

Cultural chronology of the eastern Snake River Plain

The first human beings to tap the resources of what we now call the Snake River Plain likely were descendants of people who crossed the Bering Strait land bridge;  they arrived here some 11,000 B.P.  That date was obtained from cultural deposits in Owl Cave (Wasden Site) just east of the INEEL.  A date of 14,500 B.P. was obtained three decades ago during the infancy of radiocarbon dating from deposits in Wilson Butte Cave (see Map), 200 km southwest of the INEEL (Gruhn 1965);  however, newer dating techniques applied to the same deposits provided dates younger than 11,000 years B.P. (Meatte 1989).  Other archaeological sites on the Plain, in caves and lava tubes, along the shorelines of rivers and lakes, and in the foothills, have established that humans have occupied the Snake River Plain and its edges more or less continuously ever since.  Over 850 archaeological sites at the INEEL (see Map) indicate a slow, steady increase in use of the area during that period (R. Holmer, personal communication).  Palynological and archeological studies show that plant species composition on the Snake River Plain has changed little during the Holocene (the past 10,000 years) (Davis and Bright 1983, Davis et. al. 1986, Steadman et al. 1994), but the altitudinal distributions and relative abundances of individual species likely were different during the Altithermal, a period of gradual warming and drying during the early to mid Holocene  Studies in the area indicate a peak in xeric conditions between 8,200 and 6,700 B.P. (Beiswenger 1991);  however, warm and dry conditions apparently persisted on the eastern Snake River Plain at least until 5,500 B.P. (Davis 1981)  A change in projectile point morphology around 7,500 B.P. suggests a shift in hunting technology (see Cultural Chronology)  Another shift around 4,500 B.P. may have corresponded with occupation of the area by migrants from the south following the close of the Altithermal.  The widespread climatic shift to more arid conditions during the early Holocene may have caused the earliest human inhabitants of the Plain to follow the moist conditions to which they were accustomed to higher latitudes, thus opening a niche on or around the Plain for people migrating north from the comparatively more arid conditions in the south  According to this hypothesis, the Plain’s original inhabitants were ancestors of the Plateau or Plains cultures to the north, while sometime during or toward the close of the Altithermal, ancestors of the present day Northern Shoshone and Bannock (Northern Paiute) emigrated north from the Great Basin and took up residence on the Snake River Plain (Holmer 1994).  Until the last decade this hypothesis had little support from the archaeological record, but data from two recently discovered sites are consistent with it.  A camp site at Dagger Falls on the Middle Fork of the Salmon River shows Shoshonean cultural continuity from 4,000 B.P. to historic times, and the sacred Wahmuza site on the Fort Hall bottoms shows similar continuity from 2,000 B.P. (Torgler 1995, Holmer 1994).  The temporal, contextual, and artifactual overlap between these two sites seems to confirm continuous Shoshonean presence in southern Idaho since the close of the Altithermal.   

 


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