Collaborative Proposal: Landscape Reconstruction in Zacatecas, Mexico

该项目将提供有关公元500-900年中美洲北部边境气候变化和人类影响的新信息，在这一时期，文明触及了以前由小村庄和狩猎采集者组成的地区。在墨西哥的瓜纳华托、哈利斯科、萨卡特卡斯和杜兰戈，大型的仪式中心如雨后春笋般涌现，周围都是人群。在萨卡特卡斯的La Quemada遗址附近有一个这样的种群群，这是本研究的场景。在公元500-900年间，一个大型社区统治了山谷及其支流，拥有一个纪念性的仪式中心，道路，广阔的梯田系统，以及沿马尔帕索河的200多个村庄。亚利桑那州立大学的本·纳尔逊教授和博士候选人米歇尔·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、磁性样品和木炭，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对这些样本进行分析，以检验有关植被、侵蚀、洪泛平原特征和火灾变化的假设，这些变化发生在拉克迈达周围一段人类密集定居时期之前、期间和之后。他们将通过在洪泛区切割沟槽，以及通过调查景观来记录地形和可能导致洪泛区沉积物和土壤堆积的母质来恢复这些信息。他们的目标是重建这种积累的历史及其与人类职业的关系。长期以来，考古学家一直怀疑环境的变化在该地区的文明波动中发挥了作用。他们假设殖民者在降雨增加的时期在边境定居，几个世纪后，气候逆转导致该地区被遗弃。自从佩德罗·阿米利亚斯提出“干旱边缘”假说以来，考古学家已经了解了大量以拉克迈达为中心的定居点。最近的研究已经澄清了这一职业的许多方面，但这些信息不足以解决干旱边缘假说。收集到的材料将允许对这一假设进行系统的评估，包括几个独立的数据类别，包括花粉、植物岩、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调查过北部边境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了这一时期的降水通量；在南部，湖泊沉积物包含了潜在相关事件的证据。然而，经验表明，一个山谷或湖泊的事件不能轻易地从另一个山谷或湖泊的事件中预测出来。这项研究将提供信息，最终将允许在一个广泛的区域内长时间尺度上评估人类与环境的相互作用。调查人员计划将他们的发现不仅传达给他们自己的专业人士，还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.