Sapwood estimates in the interpretation of tree-ring dates

Many timber finds lack some or all of the outer, sapwood rings formed in the years just before felling. In order to estimate felling date once the outermost remaining ring has been dated, it is necessary to estimate the number of sapwood rings originally present. Methods doing this for oak are reviewed in the light of an intensive study of living trees at one site and an extensive study of 175 samples from living trees in North Wales and northwest England. Some methods reported in the literature are found to be invalid. A method reported by Hollstein (1965) is most reliable, with modifications for known variations in sapwood number with position in the tree. At present the best available estimate is that a value of 30 sapwood rings be used (95% confidence limits: 19–50).     

Holocene climatic change and past Irish societal response

The extent to which North Atlantic Holocene climatic perturbations influenced past human societies is an area of considerable uncertainty and fierce debate. Ireland is ideally placed to help resolve this issue, being occupied for over 9000 yr and located on the eastern Atlantic seaboard, a region dominated by westerly airflow. Irish bog and lake tree populations provide unambiguous evidence of major shifts in surface moisture through the Holocene similar to cycles recorded in the marine realm of the North Atlantic, indicating significant changes in the latitude and intensity of zonal atmospheric circulation across the region. To test for human response to these cycles we summed the probabilities of 465 radiocarbon ages obtained from Irish archaeological contexts and observe enhanced archaeological visibility during periods of sustained wet conditions. These results suggest either increasing density of human populations in key, often defensive locations, and/or the development of subsistence strategies to overcome changing conditions, the latter recently proposed as a significant factor in avoiding societal collapse. Regardless, we demonstrate environmental change is a significantly more important factor in influencing human activity in the landscape than has hitherto been acknowledged.     

A dendrochronological investigation of stringed instruments from the collection of the Cherubini Conservatory in Florence,Italy

A total of forty-nine stringed instruments of the Conservatory Cherubini collection, at the Musical Instruments Department of the Accademia Gallery in Florence, were submitted to a dendrochronological investigation in order to date them, check the validity of their attribution and to find out more about their construction characteristics. Thirty-seven instruments were successfully dated, thereby determining the terminus post quem date of manufacture. The correlation values of the statistical cross-dating tests were generally very high. The dendrochronological analyses determined which instruments had been made from wood of the same provenance and, in some cases, from the same tree trunk. The mean chronology built from the musical instrument series, named “Accademia Master Chronology”, is 558 years long and dates from 1396 to 1953AD. The interval between the youngest ring dated dendrochronologically and the given date of manufacture increased constantly in the course of the centuries, from a mean value of just over eleven years for instruments built in the eighteenth century, to nearly 74 years in the twentieth century, when the use of old wood from other artefacts became more frequent. Furthermore, in the Cherubini Collection, the average tree rings on violins are smaller than those of other stringed instruments; in fact, they increase in proportion to instrument size and are widest in cello and double bass.     

Dendroarchaeology of the mid-first millennium AD in Constantinople

The 1st millennium AD was a time of great transition in Europe and the Mediterranean. At the heart of the Byzantine Empire, Constantinople (modern day Istanbul) was a pivotal trade hub for the Aegean region. Establishing a precise and accurate dating framework for the development of this remarkable city and a chronological reference for this critical time period for the Mediterranean region is of great importance to a wide range of scholars. Here we present a new 213 year tree-ring record from 89 oak samples placed in time by dendrochronology and supported by radiocarbon analysis and historical documentation. It represents the middle of the first millennium AD in Constantinople. The tree-ring series are derived from pilings recovered from the extraordinary excavations of the so-called “Theodosian harbor” at Yenikap?, Istanbul, along with timbers from other sites and buildings around the city, including one of the most famous sites on the Istanbul sky-line—Hagia Sophia. They provide potential for new insight into a time period in which earthquakes, the Justinianic plague, and even a possible tsunami struck the city, and during which dramatic changes in climate have been recorded in other paleoenvironmental proxies. The chronology is the first published tree-ring series from the Aegean region to cover the ‘event’ years of AD 536–7 and 542 which are characterized by anomalous growth in other tree-ring series from around the world, but interestingly these event years are not evident in this tree-ring sequence.     

The fort in the doctor’s house: using tree-ring growth patterns to discover historic Fort Wayne,Indiana, USA

Local Fort Wayne, Indiana (USA) lore says that the Dr. Merchant Huxford House contains timbers from Fort Wayne, the US military outpost constructed in 1794 by General Anthony Wayne. The wilderness fort played roles in Native American and British conflicts and was the genesis for a city with a current population of more than 250,000. The doctor’s residence was built on the outskirts of the young city, but within 0.4 km of the fort site. Accounts contemporary to the house’s construction describe timbers being recycled from the fort for use in new building projects. This article describes the use of dendrochronological methods to establish a construction date for the Huxford House and attempts to confirm or dispel accounts that the house contains recycled timbers from the historic fort.     

Tree-rings and archaeology: some problems explained

Some uncertainty amongst archaeologists about dendrochronology has prompted an explanation of some of the points which cause most concern. These include the probability of obtaining a date for a wood sample and the reliability and accuracy of that date. Uses of tree-ring analysis, other than for dating, are also mentioned.     

Locating the origins of wood resources: a review of dendroprovenancing

Dendroprovenancing studies have been shown to have historically been initiated on the use of oak in art-historical contexts, but are now employed on a much wider range of species and artefact types, particularly in relation to ship remains. The commonest methodology is to compare individual site chronologies with a network of other chronologies, and to recognise trends in the geographical distribution of strong matches, suggesting the likely source area of the material. Other studies may look at the matching of individual timbers to draw similar conclusions. It is shown that ecological and genetic factors may strongly influence individual matching results and that ring-widths may therefore be considered a somewhat crude means of provenancing. Additional chemical and genetic markers are discussed, although these are unlikely to become routinely used in the near future.     

Dating of 4th millennium BC pile-dwellings on Ljubljansko barje,Slovenia

We present absolute dates of seven late Neolithic pile-dwellings on Ljubljansko barje, Slovenia. They were settled from ca. 3600 to 3332 (±10) and from 3160 to 3071 (±14) cal BC, as shown by investigations of wood using dendrochronology and radiocarbon wiggle-matching. We defined eleven periods of intensive tree felling (and building activities) and one major settlement gap (when no trees were felled) from 3332 to 3160 cal BC. A major settlement gap presumably also followed after 3071 cal BC (i.e., after the end date of the investigated sites). Our investigations included over 2500 pieces of wood, mainly from the piles on which the dwellings were built. Among important wooden artefacts were a wheel with axle (one of the oldest preserved wheels in the world) and two dugout canoes, all from the settlement phase from 3160 to 3100 cal BC. As shown by parallel studies, the economy in the sites was characterized by copper metallurgy, skilful wood processing and use, cultivation of domestic plants, gathering of wild plants, animal husbandry, hunting and fishing. The settlements were contemporaneous with a number of sites in the north of the Alps, the younger ones coincided with the lifetime of the Neolithic Iceman (Ötzi). Since Ljubljansko barje has a strategic position at the crossroads between western central and (south) eastern Europe the presented absolute dates provide a basis for their comparison with other dated contemporaneous sites (in the west), to revise the chronology of similar sites in the (south) east (which are not yet exactly dated), and to evaluate their interconnection and roles in cultural development in prehistory.     

Dendrochronology reveals the construction history of an early 19th century farm settlement,southwestern Virginia,USA

The McDonald Farm (also called the Anderson-Doosing Farm) in Catawba Valley, Virginia dates to 1789 and is registered with the National Register of Historic Places maintained by the National Park Service. According to written accounts, oral histories, and architectural analyses, the construction of four structures (a collapsed cabin, a standing cabin, a barn, and a smokehouse) at the farm likely occurred in the early to mid-19th century. To verify and refine the construction dates of the four structures, we absolutely dated the tree rings in logs used in their construction by comparing their ring patterns with a composite reference tree-ring chronology created from four regional locations. We used established graphical and statistical techniques used in dendrochronology to ensure that all tree rings were dated absolutely with 99.99% certainty. We found cutting dates for the collapsed cabin ranged from 1809 to 1810, making the likely builder Samuel Myers and not Joseph Anderson, who is currently given credit for its construction. The logs in the barn had cutting dates ranging from 1830 to 1831, confirming the 1830 construction date estimated by the historical documents and confirming the builder was Joseph Anderson. The logs from the standing cabin and smokehouse had cutting dates ranging from 1838 to 1840, refining the “mid-19th century construction” listed in the register nomination. Furthermore, the nomination gave credit of the construction of these latter two structures also to Joseph Anderson, but the builder was actually John Gish who owned the farm from 1837 to 1845. Our study demonstrates the benefit and reliability of using dendrochronology to verify and refine construction dates and ownership histories of historic structures in the Southeastern U.S.     

Oaks,tree-rings and wooden cultural heritage: a review of the main characteristics and applications of oak dendrochronology in Europe

We overview the recent development of oak dendrochronology in Europe related to archaeology and art-history. Tree-ring series of European oaks (Quercus robur and Q. petraea) have provided a reliable framework for chronometric dating and reconstruction of past climate and environment. To date, long oak chronologies cover almost the entire Holocene, up to 8480 BC and the network over the entire area in which the two oaks grow is being improved. We present the main characteristics of oak ring series and discuss the latest methodological advances in defining the calendar year in which the tree-rings were formed and in interpreting such dating in terms of the age of a wooden object. Dendrochronology has established itself as a standard dating tool and has been applied in a wide variety of (pre-)historical studies. Archaeological wood, historical buildings, works of art (such as panel paintings and sculptures) have been successfully investigated. Recent advances in dendro-provenancing have helped to obtain more information on the timber trade in the past. Information on past forest structures, silviculture and timber use have become available through scrutinizing historical and contemporary ring-width patterns.