Archaeomagnetic Dates and the Hohokam Phase Sequence

Few things in Southwestern archaeology are so widely and hotly contested as the Hohokam phase sequence and chronology. Presently, no fewer than 12 different Hohokam chronologies exist and more appear to be under production. Disputes concerning the Hohokam chronology involve not only the dating of phases but also, even more basically, challenges to the integrity of the phase definitions. In the last decade, controversy has focused on three aspects of the chronology; (1) the validity and ordering of phases, (2) the argument that phases defined by pottery types overlap in time, and (3) the calibration of the phase sequence. In addition to these frequently addressed issues sufficient data presently exists to investigate the contemporaneity of phases across the Hohokam range. The over 695 archaeomagnetic samples collected from Hohokam sites in the last decade provide a data base for evaluating most of the issues surrounding the Hohokam chronology. While a major objective of archaeological efforts in southern Arizona has been to firm up the Hohokam chronology, this problem has not been addressed effectively in the context of site specific or project specific analyses of archaeomagnetic dates. On a specific site or in a specific project the number of samples has been small, and often the samples relate to only a restricted time period within Hohokam prehistory. Further, concern remains that dates derived from a curve at least partially calibrated with Hohokam dates might be in error. When gathered together as a whole the nearly 700 samples taken in southern Arizona provide an impressive empirical base for addressing chronological concerns. This report and the analysis on which it is based are the result of support provided by the Arizona Projects Office, U.S. Bureau of Reclamation.在美国西南部考古学领域，鲜有议题能如霍霍坎（Hohokam）文化分期序列与年代学一般，引发如此广泛且激烈的争议。目前已存在至少12种不同的霍霍坎文化年代学框架，且仍有更多相关研究正在推进中。围绕霍霍坎文化年代学的争议，不仅涉及各分期的断代问题，更根本性的是，还直指分期定义本身的严谨性是否成立。近十年来，相关争议主要集中于年代学的三个维度：其一，各分期的有效性与排序逻辑；其二，基于陶器类型定义的分期存在时间重叠的主张；其三，分期序列的年代校准问题。除却上述高频讨论的议题，当前已积累充足数据，可用于研究霍霍坎文化分布区内各分期的时间共存性。 近十年来从霍霍坎文化遗址采集的逾695件考古磁学（archaeomagnetic）样本，为评估霍霍坎文化年代学相关的绝大多数议题提供了数据基础。尽管亚利桑那州南部的考古研究核心目标之一是完善霍霍坎文化的年代学体系，但针对考古磁学测年的遗址专属或项目专属分析，却未能有效解决这一问题。在单个遗址或单个项目中，所采集的样本数量往往有限，且通常仅覆盖霍霍坎史前史中某一狭窄的时间区间。此外，学界仍存在担忧：基于至少部分依托霍霍坎年代数据校准的古地磁曲线所得出的测年结果，可能存在误差。而当将亚利桑那州南部采集的近700件样本整合为整体数据集时，便形成了一个颇具说服力的实证基础，可用于解决各类年代学相关的争议。 本报告及其依托的分析研究，均得益于美国垦务局亚利桑那项目办公室的资助。