Stratigraphy and geochronology of La Playa archaeological site, Sonora, Mexico

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• 作者：Audrey Copeland^a ; ^{acopelan@email.arizona.edu} ; Jay Quade^b ; James T. Watson^a ; ^c ; Brett T. McLaurin^d ; Elisa Villalpando^e
• 关键词：Early Agricultural period ; Quaternary stratigraphy and geochronology ; Stable isotopes ; Northern Mexico
• 刊名：Journal of Archaeological Science
• 出版年：2012
• 期刊代码：137_03054403
• 类别：soc
• 出版时间：September, 2012
• 卷：39
• 期：9
• 页码：2934-2944
• 文件大小：1379 K

摘要

La Playa archaeological site in northern Sonora, Mexico contains a long record of human activity that includes the Paleoindian period (terminal Pleistocene) and much of the Holocene. The size and complexity of La Playa has discouraged a systematic characterization of its stratigraphy and geochronology, a deficiency we redress in the study. We distinguished seven stratigraphic units ranging in age from >44,570 to 400聽cal聽yr聽B.P. using ¹⁴C dates from charcoal and terrestrial gastropods found mostly in archaeological features. All of the buried (in situ) cultural remains are contained in Units B (4690-1580聽cal聽yr聽B.P.) and C (1010-400聽cal聽yr聽B.P.) and represent overbank deposition from the nearby Rio Boquillas. Occupation at the site peaks in Units B₄ and B₅, corresponding to the Cienega phase (2800-1800聽cal聽yr聽B.P.) of the Early Agricultural period. This period coincides with the growth of early agricultural villages in the region and is marked at La Playa by thousands of archaeological features including roasting pits, human burials, and extensive canal irrigation systems. The presence of semi-aquatic and aquatic snails demonstrates that water was present year round in the canal systems constructed during this period. Stable and radiometric isotopic evidence suggests that early agriculturalists diverted ground water over several kilometers from the nearby Rio Boquillas. The extensive Cienega phase occupation ended after about 1700聽cal聽yr聽B.P. with deep erosion of the site, an event also visible in alluvial records in southern Arizona that marked the end of the Early Agricultural period and significant changes in settlement organization in the region.