A comparison of the treatment of errors in radiocarbon dating calibration methods

The application of radiocarbon dating to archaeological samples generally requires calibration of ¹⁴C dates to calendar ages and interpretation of dating errors. In this paper, four recent methods of age calibration are assessed, particularly with regard to their quality of error treatment. Recent experimental research has suggested that commonly quoted errors on “raw” ¹⁴C dates may require enlargement to more realistic levels, which, when incorporated in the calibration schemes, produce a considerable increase in the size of the typical calibrated interval. A general decrease in the sensitivity of ¹⁴C dating using single, “normal precision” dates is implied. Thus typical calibrated age intervals range from 300 to 1300 years (approximate 95% confidence level), with little improvement resulting if “high precision” calibration systems are used to correct “normal precision” dates. Of the four methods considered here, that proposed by Neftel is found to provide the most objective, flexible, comprehensive and “easy to use” scheme. This method is particularly recommended for its treatment of errors both on the dates to be calibrated and on the calibration curve itself.     

Seasonal dating and the valve-pairing technique in shell-midden analysis

Three-dimensional excavation of 23 artifact fragments and 4382 shells was carried out in the shell layer of an abandoned dwelling pit. Principal component analysis using three locational variables was used for drawing the central axes and the regression plane of the shell layer. Valve-pairing carried out on the clam Meretrix lusoria indicated that 380 pairs could be established among a total of 2089 unbroken valves. Preservation of shells was estimated at 70% by comparing the number of shells found in the shell layer with the clam population size which was in turn calculated by a probability formula using paired valves among samples. In addition to these data, the distance separating pairs gave some idea of the movement of shells. Seasonal dating by daily growth line counting showed that the shell layer could be subdivided into at least three main seasonal layers and that the period of accumulation was approximately 500 days.     

历表、系连与年代史料（续）——关于西周诸王年代的讨论

本文在上一篇论文的基础上继续使用系连排谱的方法,对剩余的完整历日铜器所属的时代进行判定,进而排定十二位周王的在位年代;并确认西周王朝始于公元前1071年武王克商,终于公元前771年骊山之役。     

古代瓷器热释光测定年代制样方法的比较与研究

为了对古代瓷器热释光年代测定的两种不同制样方法——粉末法和薄片法的优劣进行比较,本工作从热释光灵敏度的均值标准偏差、三点回归的线性相关程度以及最后所测得年代与真值的符合情况等方面进行研究。研究结果表明,粉末法的测量精确度、准确度及可靠性均优于薄片法。粉末法可作为行业内制样标准参考。     

中国海南省中和镇古城墙砖的热释光测年研究

采用热释光前剂量饱和指数法对海南省中和镇的8件古城门墙砖样品进行了年代测定研究。由于该地区离海近,粘土中的含沙量非常高,古人在烧制砖时,采用这种粘土作为制砖的原料。烧造时的温度相对高于其它地方烧制的砖。其中4件砖样内部呈灰色,3件砖样内部呈红色,其中1件砖样断面为外围灰色,内部红色。在应用高温细颗粒方法测定这批砖样的年代时,发现样品的高温热释光灵敏度非常差,且不规则,没有\"坪曲线\",因而无法得出这些古代城门墙砖的具体年代。后采用热释光前剂量饱和指数方法对古砖样品进行了古剂量测定,发现这些样品具有较好的热释光前剂量效应,且样品的热释光灵敏度较高,得到的古剂量具有很好的重复性。热释光测年结果表明,No.2、No.3、No.6、No.8样品的热释光年代分别为:距今590年、575年、530年和580年,为明代早期烧制;No.1、No.4、No.7样品的热释光年代分别为:距今410年、345年和375年,为明代中晚期烧制;No.5样品的年代为距今140年,为清代晚期。经考古人员现场考证,认为No.5样品所处位置存在火烧痕迹。这个火烧时间应该在中国清代晚期,即热释光测定年代。     

Thorium-230 coral chronology of a late prehistoric Hawaiian chiefdom

Documenting the history of settlement in Hawaii during the last few centuries before European contact, is crucial to charting the evolution of the most complex chiefdom in Polynesia. It is precisely this period that Hawaii, and many Polynesian societies, underwent their most rapid changes in political, economic and social organisation. The last ∼500 to 300 years in the ¹⁴C calibration curve is problematic with wide fluctuations often rendering large age spans that do not precisely date single events, especially troubling with a culture-historical record of ∼1000 years duration. Here we present an extremely high precision ²³⁰Th chronology for archaeologically constrained coral samples from a range of occupancy sites. Our high precision dates allow the time of site use to be clearly demonstrated. They also provide the first dates for habitation sites in Hawaii that clearly show contemporaneous occupation—the major problem in settlement pattern archaeology. We demonstrate that two sites were occupied within the same year. Our refined chronology, provides new and exciting opportunities for tracking sociopolitical and economic developments during the last few centuries—the crucial period in the evolution and transformation of Polynesian societies.