Collaborative Proposal: Landscape Reconstruction in Zacatecas, Mexico

这个项目将产生关于公元500-900年间中美洲北部边境地区气候变化和人类影响的新信息，在这段时期，文明触及了以前居住着小农业村庄和狩猎采集者群体的地区。在墨西哥的瓜纳华托、哈利斯科、萨卡特卡斯和杜兰戈，大型仪式中心如雨后春笋般涌现，周围聚集着人口。这项研究的场景就是萨卡特卡斯省拉奎马达周围的一个这样的种群聚集地。在公元500-900年间，一个庞大的社区统治着山谷及其支流，拥有一个纪念性的仪式中心、道路、广泛的梯田系统，以及马尔帕索河沿岸的200多个村庄。亚利桑那州立大学的本·纳尔逊教授和博士生米歇尔·埃利奥特以及肯特州立大学的克里斯托弗·费舍尔教授将与国立自治大学的地质学家罗伯托·莫利纳合作，收集植物遗骸、沉积物、磁性样本和木炭，用于放射性碳测年，并绘制该地区的地质图。他们和其他科学家将分析样本，以测试有关植被变化、侵蚀、泛滥平原特征以及在拉奎马达周围密集人类聚居期之前、期间和之后发生的火灾的假设。他们将通过在泛滥平原上开凿沟渠以及测量地貌来记录可能导致泛滥平原沉积物和土壤积累的地貌和母质，从而恢复这些信息。他们的目标是重建这种积累的历史及其与人类占领的关系。考古学家长期以来一直怀疑环境的变化对该地区文明的波动起到了作用。他们假设，殖民者在降雨量增加的时期定居在边境，几个世纪后，气候逆转导致该地区被遗弃。自从佩德罗·阿米拉斯提出这一“干旱边缘”假说以来，考古学家们对以拉奎马达为中心的定居点有了很多了解。最近的研究澄清了这一职业的许多方面，但信息不足以解决干旱边缘假说。收集到的材料将允许系统地用几类独立的数据来评估这一假说，包括花粉、植物硅体、大型植物遗骸、磁化率、沉积物特征和放射性碳分析。考古学家还没有以如此全面的方式研究过北方边疆任何地区的古代环境变化。在研究区域的北部，对美国西南部沙漠溪流的研究表明，这一时期的降水通量；在南部，湖泊沉积包含潜在相关事件的证据。然而，经验表明，一个山谷或湖泊中的事件不能轻易地从另一个山谷或湖泊中预测出来。这项研究将提供最终能够在大范围内长期评估人与环境相互作用的信息。研究人员计划不仅将他们的发现传达给他们所在行业的人，而且还将传达给一系列生态学家、地质学家、地理学家、政府官员和感兴趣的社区成员。

This project will produce new information about climatic changes and human impacts along the Northern Frontier of Mesoamerica, A.D. 500-900, a period when civilization touched areas previously populated by small farming villages and bands of hunter-gatherers. In Guanajuato, Jalisco, Zacatecas, and Durango, Mexico, large ceremonial centers sprang up, surrounded by clusters of population. One such population cluster around the site of La Quemada, Zacatecas, is the scene for this study. Between A.D. 500-900, a large community dominated the valley and its tributaries with a monumental ceremonial center, roadways, extensive terrace systems, and over 200 villages along the Malpaso River. Professor Ben Nelson and doctoral candidate Michelle Elliott of Arizona State University, along with Professor Christopher Fisher of Kent State University, will collaborate with geologist Roberto Molina of the National Autonomous University, to collect plant remains, sediments, magnetic samples, and charcoal for radiocarbon dating and to create a geological map of the area. They and other scientists will analyze the samples to test hypotheses about changes in vegetation, erosion, floodplain characteristics, and fires that occurred before, during, and after a period of intensive human settlement around La Quemada. They will recover this information by cutting trenches in the floodplain as well as by surveying the landscape to record landforms and parent materials that may have contributed to the accumulation of sediments and soils in the floodplain. Their goal is to reconstruct the history of that accumulation and its relationship to human occupation.Archaeologists have long suspected that the changes in the environment played a role in civilization's fluctuations in this region. They hypothesize that colonists settled the frontier during a period of increased rainfall and that several centuries later, a climatic reversal led to the region's abandonment. Since Pedro Armillas formulated this "arid margin" hypothesis, archaeologists have learned a great deal the settlements centered on La Quemada. Recent research has clarified many aspects of this occupation, but the information is inadequate to address the arid margin hypothesis. The collected materials will allow systematic evaluation of this hypothesis with several independent classes of data, including pollen, phytoliths, macrobotanical remains, magnetic susceptibility, sediment characterization, and radiocarbon assays.Archaeologists have not investigated ancient environmental change in any part of the Northern Frontier in such a comprehensive way. To the north of the study area, studies of desert streams in the American Southwest indicate precipitation flux for this period; to the south, lake deposits contain evidence for potentially related events. Experience shows, however, that events in one valley or lake cannot be readily predicted from those in another. This study will provide information that will ultimately allow evaluation of human-environmental interactions on a long time scale over a wide region. The investigators plan to communicate their findings not only to people in their own profession, but to a range of ecologists, geologists, geographers, government officials, and interested community members.