A simple Bayesian approach to tree‐ring dating

Tree‐ring dating involves matching sequences of ring widths from undated timbers to dated sequences known as ‘master’ chronologies. Conventionally, the undated timbers (from a building or woodland) are sequentially matched against one another, using t‐tests to identify the relative offsets with the ‘best’ match, thus producing a ’site’ chronology. A date estimate is obtained when this is matched to a local master chronology of known calendar age. Many tree‐ring sequences in the UK produce rather low t‐values and are thus declared not to have a ‘best’ match to a master chronology. Motivated by this and the routine use of Bayesian statistical methods to provide a probabilistic approach to radiocarbon dating, this paper investigates the practicality of Bayesian dendrochronology. We explore a previously published model for the relationship between ring widths and the underlying climatic signal, implementing it within the Bayesian framework via a simulation‐based approach. Probabilities for a match at each offset are produced, removing the need to identify a single ‘best’ match. The Bayesian model proves successful at matching in both simulated and real examples.     

Tree‐Rings,Timbers and Trees: a dendrochronological survey of the 14th‐century cog,Doel 1

In 2000, the remains of a cog, Doel 1, were found in Doel, Belgium. Wood species identification of all ship timbers and smaller elements was performed. European oak was the dominant species, followed by alder that was used for the fairings. In total 150 ring‐width series were recorded. The construction date was set at AD 1325/26 and the timbers proved to originate from forests along the rivers Elbe and Weser. For the bottom strakes a strict symmetrical layout was observed. The keel plank was hewn from a trunk with a slightly earlier felling date. Repairs were performed with high‐quality boards, some with a southern Baltic provenance.     

The Post Medieval Gravellona Toce Boat: an inland watercraft from north‐west Italy assembled using locked dowels

Discovered in 1955, not far from the Roman necropolis of Pedemonte, the Gravellona Toce boat has long been considered evidence of Roman‐period riverine navigation in northern Italy. This initial interpretation, which was not supported by direct dating evidence, has been recently reconsidered on the basis of radiocarbon‐dating and analysis of the timbers retrieved. In this paper, the authors present the results of the recent analysis of the surviving remains which allow the vessel to be interpreted as a post medieval boat built using the traditional bottom‐based construction techniques of the Po Valley region.     

故宫武英殿建筑群木构件树种及其配置研究

我们从武英殿建筑群的武英门、武英殿、敬思殿、武英门东西值房、东配殿及北值房、西配殿及北值房、恒寿斋、井亭11座建筑的20余种木构件上,共采集1145个样本进行树种鉴定。结果表明,武英殿建筑群共使用了15个种或属的木材,其中有落叶松、软木松、硬木松、冷杉、云杉、黄杉、柏木、杉木、圆柏、金钱松等10种针叶材,桢楠、椴树、润楠、喃喃果、印茄等5种阔叶材。其中,杉木、桢楠和润楠是我国南方树种,喃喃果和印茄是东南亚进口材。武英殿主要承重木构件选用主要为北方树种中密度和力学强度较高的落叶松、黄杉和云杉,其他木构件则主要使用的是密度低、重量轻的软木松;敬思殿主要承重木构件使用的是云杉,其他木构件也以软木松为主,但使用的木材比较杂,角梁和爬梁全部使用了东南亚进口阔叶材;敬思殿在选材方面与武英殿的差异,可能是在光绪三十年重建时选材标准不如武英殿严格所致。武英门的木材,硬木松占了绝大多数,使用的都是强度较大的木材。所有配殿和值房的主要承重构件中,柱使用最多的是硬木松,其次是落叶松、软木松;月梁、三架梁和四架梁、瓜柱、四架梁随梁、抱头梁及其随梁木构件使用的是杉木,配殿、值房等建筑的梁没有使用强度高的木材。是以南方树种为主,其中某些主要构件还使用了珍贵的南方阔叶树种如桢楠、润楠等。这种情况表明,恒寿斋和井亭是武英殿几次大火后的仅存建筑,因而保留了明代建造时选材的历史信息。木材的使用差异具有一定的时代意义。从润楠在恒寿斋的柱和梁上,椴树、桢楠和润楠在斗棋上使用,以及根据构件的承重和位置不同进行树种配置,既考虑了对主要建筑结构材的强度要求,也考虑了尽可能减小其他木构件对主要构件的负荷,这种按照木材物理力学的性质和木材承重强度等因素进行选材的建筑原则,相当清楚地表明当时吉建筑在科学选材方面已达到很高的水平。在故宫维修工程中通过对各种木构件树种配置的研究,进行科学定性分析,将深层次地探索古建筑留给我们的历史痕迹和信息,揭示其科学性,为制定维修保护方案提供科学依据,并为故宫古建筑保护研究提供新的方法,丰富故宫历史档案资料。     

An English Tree-Ring Chronology,A.D. 404–1216

AN 813-YEAR OAK CHRONOLOGY, A.D. 404–1216, is presented. Its construction has taken three years because of the difficulty of finding suitable Saxon timbers and the need to test the reliability of the dating. Although based on only a few timbers for the period c. A.D. 700, it can be used to date Saxon and medieval timbers whilst more material is found to consolidate that section of the chronology.     

New Dating and Contextual Evidence for the Fragmentary Timber Remains Located in the Dor D Site, Israel

The laboratory report for a wood-sample taken from one of the ship-timbers discovered at the Dor D site for C14 analysis is completed. This dating result indicates a potential revision for the group of timbers in this deposit and, consequently, new chronological contexts for their construction characteristics. Subsequent excavation and survey in the lagoon has resulted in a revised interpretation for the components of the Dor D deposit. Taken together, this new dating and contextual evidence helps to clarify what these timbers can and cannot contribute to the understanding of trends in ship construction.
© 2005 The Nautical Archaeology Society     

An Arab-Period merchant vessel at Tantura Lagoon, Israel

During the excavation and analysis of a 6th-century AD vessel in Tantura Lagoon, Israel, members of the joint Institute of Nautical Archaeology and Center for Maritime Studies team located an Arab-Period vessel in the vicinity. The dating of the vessel to the 8th–9th century AD is based on pottery, found in association with timbers. Only a matter of days before the end of the excavation season, one end of the vessel was unearthed and preliminary recordings, drawings, and photographs were made. None of the timbers were removed from their in-situ positions for analysis as both time and facilities were not permitting. Though a full analysis was not possible, information gleaned during the several days of recording affords an understanding of the ship's construction.     

Dendrochronological Dating and Provenancing of Timbers from the Arade 1 Shipwreck,Portugal

As part of a larger project promoting the development of historical dendrochronology in the Iberian Peninsula, ship‐timbers from the Arade 1 wreck (mostly planking and framing elements), stored at the DANS/IGESPAR in Lisbon, were examined. Of these, 52 samples were identified as deciduous oak (Quercus subg. quercus) and two as chestnut (Castanea sativa). Of 24 timbers selected for dendrochronological research, 23 could be dated, placing the origin of the wood in western France and the felling of trees between AD 1579 and 1583. Their homogeneity suggests they are part of the original construction, which probably took place shortly after AD 1583. © 2012 The Authors     

Medieval Britain in 1980

THIS PAPER briefly outlines earlier work in southern England and discusses particular problems associated with the tree-ring dating of building timbers in the region. Specific examples from recent research not only highlight these problems, but show the success that may also be achieved. A new regional chronology for southern England, constructed entirely from building timbers, is presented and its use and further development discussed.     

Radiocarbon Wiggle-Match Dating in the Intertidal Zone

Radiocarbon wiggle-match dating is a technique that can combine the versatility of radiocarbon dating with chronological information from tree-rings. This makes it useful in contexts where timbers are preserved, but dendrochronological dating is impossible. As intertidal and marine timbers are waterlogged, this can favor their preservation and hence allow wiggle-match ¹⁴C dating, which can be of significant help in deriving relatively precise chronologies for a range of coastal structures. As the technique depends on making multiple radiocarbon measurements towards a single date, efficiency in application is the key and hence a number of practical considerations need to be taken into account in advance of conducting a dating program. This paper discusses some of these practical concerns and reviews them in the context of the intertidal crannogs in the Firth of Clyde on the west coast of Scotland.     

Some thoughts on art-historical dendrochronology

Imported timbers pose potential problems for the dendrochronologist. The problem is general and any particular dendrochronologist may run into difficulty when he attempts to correlate an exotic ring pattern against an indigenous chronology. Sufficient evidence exists to suspect that high quality oak boards and planks were extensively imported into England in medieval times. However, chronologies constructed from just such boards, namely the art-historical chronologies, have been treated as indigenous without being proven to be so. Almost identical comments can be made with respect to art-historical chronologies constructed by German workers using supposedly indigenous Flemish oak panels. This article explores how failure to allow for importation may well call into question the dating of these art-historical chronologies and in addition demonstrates how an art-historical dating system has been created wherein erroneous placement of the chronologies could escape detection (this latter aspect may well make the argument of general interest to scientists).     

Dendrochronological dating of a wooden causeway in Finland

A mean ring‐width chronology for Scots pine in eastern Finland has been compiled based on living trees and dendrochronologically dated historical timber constructions. As an application of this master chronology, a young archaeological site near the town of Hämeenlinna, southern Finland, was dated. A previous assumption of the age of this site was that it could even be medieval. The construction was not older than 160 years, the road having been built after 1828, the year of growth of the outermost tree rings of the samples. A new pine chronology for southern Finland extending to the year AD 1539 is presented and it is now applicable for precise dating purposes in this area.     

OPTICAL DATING OF GRANITIC STONE SURFACES*

A novel luminescence methodology for dating surfaces of granitoid rocks is presented, with encouraging results for archaeological stone structures. It is based on the zeroing of the latent signal of optically stimulated luminescence (OSL) in feldspar and quartz grains of the stone surface during exposure to daylight. When after bleaching the surface is shielded from light, the OSL signal builds up again, such that its intensity provides an age for the event of the last exposure to light. This event could be the construction or the destruction of stone structures or, for example, sedimentary deposition of granitic boulders, such as in fan deposits. The experimental approach utilizes a high spatial resolution detection technique (HR‐OSL) for OSL of minerals that are left in their original petrological context; that is, without any mineral separation. With this approach, steep gradients in microdosimetry at the surface and at grain boundaries become important and are discussed in detail. The new dating technique is successfully applied to a stone wall of the medieval castle of Lindenfels in southwestern Germany and the pre‐Columbian Nasca lines (geoglyphs) around Palpa in southern Peru.     

The Marausa Wreck,Sicily: interim report on a boat built in the Western Imperial Roman tradition

In 1991, the wreck of a late 3rd–early 4th century AD Roman merchant vessel was discovered on the west coast of Sicily that had carried North African amphora, tubuli, and other ceramics. The hull was dismantled and raised in 2011, including a keel hook‐scarfed to stem and sternposts, 39 pegged mortise‐and‐tenon joined planks, 43 frames with an irregular pattern of floor‐timbers, half‐timbers, and futtocks fastened to the planking with treenails and copper nails, sister‐keelsons and evidence of two stringers, 36 ceiling strakes, and the base of a bilge pump. Many repairs are indicated. The fairly flat bottom and round bilges, mortise‐and‐tenons, sister‐keelsons and lack of a coherent framing pattern, place the boat in the Western Imperial tradition.     

THE EVOLUTION OF CUBIC DICE

Cubic dice were brought by the Romans to the Low Countries, and are found in small numbers at many archaeological sites dating to the last 2000 years. We report on a systematic analysis of 110 well‐dated dice from the Netherlands, showing that shape, pip configuration, and pip style changed significantly for bone and antler dice from the Roman to the recent historical period. Dice predating 650 CE are highly variable in all attributes, those dating between 1100 and 1450 are highly standardized, and those post‐dating 1450 CE are standardized for some attributes, such as symmetry and configuration, but variable for others, such as material type. There is also a major shift from “sevens” to “primes” and back to “sevens” pip configuration across these temporal windows, and pip style was simplified over time from a dot‐ring‐ring pattern to simple dots. We compare these trends to a smaller set of well‐dated dice from the United Kingdom and speculate on possible reasons for these changes. The information can be used in future studies in the Netherlands to help date sites and/or isolated finds, and more broadly, can be augmented with similar analyses of dice elsewhere in Eurasia to study ancient interaction networks and the cultural transmission of games involving dice play.     

Examining Possible Driftwood Use in Viking Age Icelandic Boats

While boat and ship graves are known from across northern Europe, and are particularly associated with the Viking Age, only seven examples of such monuments have been excavated in Iceland. Furthermore, no shipwrecks are known dating from this period in Iceland, and examples of boat timbers preserved by waterlogging are very rare. As such, the mineralized wood remains from these burials comprise the vast majority of direct archaeological evidence currently available for the boats used in daily life in early Iceland. This paper uses taxonomic identification of mineralized wood remains from the Icelandic boat graves, along with comparative data from Europe and Scandinavia, to discuss boat construction and repair in early Iceland, including the possibilities of driftwood utilization and the importation of boats from Norway. The economic and social significance of the practice of boat burial in Iceland is also explored, with regard to the importance of boats as transport and the limited availability of wood suitable for boat construction and repair.     

Natural preservation mechanisms at play in a Bronze Age wooden shovel found in the copper mines of Alderley Edge

A wooden shovel, dating from the Early Bronze Age, has survived in a remarkable state of preservation in the copper mines of Alderley Edge, Cheshire UK. Other historic timbers recovered from the mines, whilst still intact, have fared less well. An X-ray investigation into the distribution of minerals through the shovel using portable X-ray Fluorescence (PXRF) along with the use of synchrotron-based X-ray Absorption Spectroscopy (XAS) measurements of the copper and arsenic chemical speciations has provided clues to the methods by which metals from the mining environment have entered the wood of the shovel and ensured its survival. The distribution and nature of the minerals so determined suggest that the copper and arsenic, along with a significant lead content, entered the shovel during its original use in working mineral-rich deposits, rather than through the burial environment. The insights gained are expected to be applicable to other wooden artefacts recovered from ancient copper mines in other places.     

A Spanish Man‐o‐War in New Zealand? The 1864 wreck of Grafton and its lessons for pre‐Cook shipwreck claims

This paper considers the 1864 wreck of Grafton in the Auckland Islands, and its implications for wreck analysis and pre‐Cook exploration claims. The captain of Grafton, Thomas Musgrave, stated that the schooner was built from the wreck of a Spanish man‐o‐war, and archaeological analysis of the wreck found that the timbers are a tropical South American species, and had possibly been reused. The implications of this are clear; it is possible that timbers that originated in pre‐Cook (1769) ships lie in New Zealand, but without a full understanding of the historical and archaeological context of any such timbers, including their reuse in later ships, it is not possible to claim proof of pre‐Cook European exploration of New Zealand.     

18th- and 19th-century shipyards at the south-east entrance to the West India Docks, London

Archaeological fieldwork in 1997 on the Isle of Dogs, at the south-east entrance to the West India Docks, recovered evidence of 17th- to 19th-century shipyards, associated activities and foreign trade. Reused timbers may be the remains of the 17th-century Rolt's yard. Reclamation along the natural inlet was accompanied by the construction of a timber dry dock probably in the late 18th century. This soon fell out of use and was filled in with the construction of new dry docks to the south in 1806 by Thomas Pitcher. Much of the debris dating to the first half of the 19th century from ship repairing and building and from a range of ancillary crafts, together with ceramics from Iberia and the Far East, probably came from Pitcher's yard.     

Resource Exploitation and Wood Mobility in Northern European Oak: dendroprovenancing of individual timbers from the Mary Rose (1510/11–1545)

Dendrochronology has proved useful in suggesting the provenance of timbers in northern Europe, particularly for ship‐timbers, which may have originated from a distant source. Historical chronologies are usually derived from timbers of uncertain origin. In trying to provenance a new chronology, therefore, trends in the geographical distribution of statistical matches should be viewed, rather than individual strong matches. While it is usual to test a site‐chronology created from several individual timbers, in a situation such as the Mary Rose, where individual timbers may have been sourced from several regions, the matches of individual timbers may shed light on their origins. © 2010 The Author