Archaeological Chronology Development and the Old Wood Problem on the Northern Colorado Plateau

在美国国家科学基金会的支持下，罗纳德·H·汤纳博士、他的同事和学生们将研究科罗拉多州西部和犹他州东部考古遗址放射性碳测年中的“老木头”问题。古老的木材问题是，从木炭中测定放射性碳(14C)的时间往往比发现木炭的环境要早得多。有五个因素可以使柴火的年代明显早于考古或现代背景：1)人们将枯木用作燃料的倾向；2)枯树或枯枝可能在其木材被用作燃料之前很久就已经死亡；3)树木死亡后的风化、腐烂或昆虫活动可能会移除许多外部环，并增加枯木残留物的日期与其使用时间之间的差距；4)通过燃烧移除额外的外环可以进一步扩大差距；5)来自木材年轮系列内部的年代轮进一步扩大了差距。单独或一起操作，这些过程可能会在日期和木材使用之间产生差距，超过放射性碳日期的不确定范围，从而严重高估了所涉及的地点的年龄。这项拟议的项目同时使用放射性碳测年和树木年轮测年，以考察采购旧木材对科罗拉多州西部和犹他州东部史前和历史时期占领的解释的影响。先前的研究表明，旧木材问题的严重程度在空间、环境、或许文化上各有不同。通过在沿环境梯度的三个地区收集大量样本，该项目将评估不同环境对薪材资源年龄和可用性的影响。当地多物种多世纪年轮年表的建立对于科罗拉多州西部和犹他州东部的弗里蒙特、盖威特传统和犹他州遗址的年代测定将特别重要，并可能对理解弗里蒙特和犹他州的关系和犹他州的民族起源至关重要。这个拟议的项目将帮助我们为这三个群体开发木材使用模型，并为遗址的年代确定提供解释性指导。因此，该项目的学术价值在于测试放射性碳测年的环境变异性，为该地区创建新的树木年轮年表，开发新的文化木材使用实践模式，并评估技术变化作为这些地区遗址放射性碳测年的一个因素。该项目将产生更广泛的影响，超出弗里蒙特、盖特传统和犹他州西部和东部的犹他州考古学。它将对了解全球干旱和半干旱环境中的放射性碳测年和木材使用实践做出重要贡献。该项目还将为研究生和本科生的培养和发展做出贡献。它还可能有助于校准其他计时技术，如考古磁学和热释光测年，并完善史前弗里蒙特和史前和早期历史尤特陶器类型的陶瓷系列化研究。它将完善木材使用模式，这些模式可能对理解技术变革对木材资源开发的影响有影响。

With the support of the National Science Foundation, Dr. Ronald H. Towner, colleagues and students will examine the 'old wood' problem in radiocarbon dating of archaeological sites in western Colorado and eastern Utah. The old wood problem is the tendency for radiocarbon (14C) determinations from wood charcoal to be significantly older than the contexts in which the charcoal is found. Five factors can make firewood dates significantly earlier than their archaeological or modern contexts: 1) the tendency of people to use dead wood for fuel; 2) a dead tree or dead branch may have died long before its wood was used for fuel; 3) weathering, decay, or insect activity after tree death can remove many exterior rings and increase the gap between the date of the deadwood remnant and the time of its use; 4) removal of additional exterior rings by burning can further expand the gap; and 5) dating rings from the inner part of the wood's ring series widens the gap still further. Operating singly or together, these processes can produce a gap between date and wood use that exceeds the uncertainty range of radiocarbon dates and thereby seriously overestimate the age of the site involved. This proposed project uses both radiocarbon and tree-ring dating to examine the impacts of 'old wood' procurement on interpretations of the prehistoric and historical period occupations of western Colorado and eastern Utah. Previous research indicates that the magnitude of the old wood problem varies spatially, environmentally, and perhaps culturally. By collecting abundant samples in three areas along an environmental gradient, the project will assess the impacts of different environments on the age and availability of fuelwood resources. The construction of local multi-species multi-century tree-ring chronologies will be particularly important for dating of Fremont, Gateway Tradition, and Ute sites in western Colorado and eastern Utah, and may be critical in understanding Fremont/Ute relationships and Ute ethnogenesis. This proposed project will help us develop wood use models for the three groups and provide interpretive guidelines for dating the sites. Thus, the intellectual merit of the project is to test environmental variability of radiocarbon dates, create new tree-ring chronologies for the area, develop new models of cultural wood use practices, and evaluate technological change as a factor in radiocarbon dating of sites in these areas.This project will have broader impacts beyond the Fremont, Gateway Tradition, and Ute archaeology in western Colorado and Eastern Utah. It will make important contributions toward the understanding of radiocarbon dating and wood use practices in arid and semi-arid environments worldwide. The project will also contribute toward graduate and undergraduate student training and development. It may also contribute to calibration other chronometric techniques, such as archaeomagnetism and thermoluminescence dating, and to refining ceramic seriation studies of prehistoric Fremont and protohistoric and early historic Ute pottery types. It will refine models of wood use that may have implications for understanding the impacts of technological change on the exploitation of timber resources.