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PDF versions are e-mailed manually and therefore may take a few days. Tree-Ring Services Providing tree-ring analysis of live trees and archaeological timbers. Dendrochronology tree-ring dating professionally applied to provide precise calendar year dates for live trees, wooden artefacts and historic building timbers.
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Tree-Ring Services is one of Britain's leading independent dendrochronology laboratories, combining affordable analysis with cutting-edge research. Our professional services include: We undertake both private and commercial commissions in dendrochronology throughout the UK: Waxham Barn — Norfolk Client: English Heritage Lime trees — London Client: Headland Archaeology Most previous reports are available for purchase and these are listed on the Building page.
Some of our more recent reports are listed below: Lime trees — London Client: Parham House — W Sussex Client: Subfossil Neolithic pine — Scotland Client: Calibration of radiocarbon results is needed to account for changes in the atmospheric concentration of carbon over time.
The most popular and often used method for calibration is by dendrochronology. The science of dendrochronology is based on the phenomenon that trees usually grow by the addition of rings, hence the name tree-ring dating. Dendrochronologists date events and variations in environments in the past by analyzing and comparing growth ring patterns of trees and aged wood.
They can determine the exact calendar year each tree ring was formed.
Dendrochronological findings played an important role in the early days of radiocarbon dating. Tree rings provided truly known-age material needed to check the accuracy of the carbon dating method.
During the late s, several scientists notably the Dutchman Hessel de Vries were able to confirm the discrepancy between radiocarbon ages and calendar ages through results gathered from carbon dating rings of trees. The tree rings were dated through dendrochronology. At present, tree rings are still used to calibrate radiocarbon determinations.
Libraries of tree rings of different calendar ages are now available to provide records extending back over the last 11, years.
Radiocarbon Tree-Ring Calibration
The trees often used as references are the bristlecone pine Pinus aristata found in the USA and waterlogged Oak Quercus sp. Radiocarbon dating laboratories have been known to use data from other species of trees. In principle, the age of a certain carbonaceous sample can be easily determined by comparing its radiocarbon content to that of a tree ring with a known calendar age. If a sample has the same proportion of radiocarbon as that of the tree ring, it is safe to conclude that they are of the same age.
In practice, tree-ring calibration is not as straightforward due to many factors, the most significant of which is that individual measurements made on the tree rings and the sample have limited precision so a range of possible calendar years is obtained.
And indeed, results of calibration are often given as an age range rather than an absolute value. Age ranges are calculated either by the intercept method or the probability method, both of which need a calibration curve.
Tree-Ring Services - dendrochronology applied to date Archaeology and Historic Building timbers
The first calibration curve for radiocarbon dating was based on a continuous tree-ring sequence stretching back to 8, years. This tree-ring sequence, established by Wesley Ferguson in the s, aided Hans Suess to publish the first useful calibration curve. In later years, the use of accelerator mass spectrometers and the introduction of high-precision carbon dating have also generated calibration curves. A high-precision radiocarbon calibration curve published by a laboratory in Belfast, Northern Ireland, used dendrochronology data based on the Irish oak.
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Nowadays, the internationally agreed upon calendar calibration curves reach as far back as about BC Reimer et. For the period after , a great deal of data on atmospheric radiocarbon concentration is available.