Bayesian analysis of the chronology of the Lynch site (25BD1) and comparisons to the Central Plains Tradition and Central Plains Oneota

This paper presents a series of new radiocarbon dates on the Lynch site (25BD1), an Initial Coalescent site in northeastern Nebraska, and takes a Bayesian approach to examining them in three contexts. First, we consider what they tell us about the chronology of occupation at the site itself. Second, we combine them with dates on other sites in the Ponca Creek drainage to consider the chronological pattern of horticultural settlement there. Finally, we compare the Ponca Creek dates to the radiocarbon chronologies for the Central Plains tradition and Central Plains Oneota. Our analysis indicates that people settled Lynch from east to west and abandoned it from west to east between roughly AD 1250 and 1350. At its maximum extent, farmers appear to have occupied the full 80 ha extent of the site. As farmers settled Lynch, closely related people settled upstream on Ponca Creek. People abandoned these communities shortly before they abandoned Lynch. Farmers settled on Ponca Creek as a whole shortly after the major expansion of Central Plains tradition (CPt) ways of life and the appearance of Central Plains Oneota towns and abandoned that area a generation or two before CPt communities disappeared. Central Plains Oneota communities persisted into the mid 1400s. The Lynch/Ponca Creek pattern is consistent with the movement of Central Plains populations into the southern portion of the Middle Missouri in the early 1300s.

本研究针对内布拉斯加州东北部的初始聚合文化遗址（Initial Coalescent site）——林奇遗址（25BD1），公布了一系列全新的放射性碳定年数据（radiocarbon dates），并采用贝叶斯方法（Bayesian approach）从三种情境下对其展开分析。其一，探讨这些数据对该遗址自身占据活动的年代学所带来的启示；其二，将这些数据与庞卡溪流域（Ponca Creek drainage）其他遗址的定年数据相结合，分析该区域园艺式定居（horticultural settlement）的年代学模式；其三，将庞卡溪流域的定年数据与中部平原传统（Central Plains tradition, CPt）及中部平原奥陶塔（Central Plains Oneota）的放射性碳年代学框架进行对比。

分析结果显示，1250年至1350年前后，人类从东向西进驻林奇遗址，又从西向东废弃该遗址。在遗址鼎盛阶段，农耕人群占据了其全部80公顷的范围。当农耕人群进驻林奇遗址时，亲缘关系密切的人群也同步在庞卡溪上游定居。这些上游聚居群落的废弃时间略早于林奇遗址。

整体而言，农耕人群在中部平原传统生活方式大规模扩张、中部平原奥陶塔城镇出现后不久，便进驻庞卡溪流域，并在中部平原传统群落消亡前一两代人的时间里废弃了该区域。中部平原奥陶塔群落则一直存续至15世纪中期。林奇-庞卡溪流域的定居模式，与14世纪早期中部平原人群迁入密苏里中游南部区域的历史进程相符。