Dendrochronology (from the Greek δένδρον = tree, χρόνος = time, and λογία = study) or tree-ring dating is the method of scientific dating based on the analysis of tree-ring growth patterns. Greek (el ελληνική γλώσσα or simply el ελληνικά — "Hellenic" is an Indo-European language, spoken today by 15-22 million people mainly This technique was developed during the first half of the 20th century originally by the astronomer A. E. Douglass, the founder of the Laboratory of Tree-Ring Research at the University of Arizona. A E (Andrew Ellicott Douglass ( July 5, 1867, Windsor Vermont – March 20, 1962, Tucson Arizona) was an American The Laboratory of Tree-Ring Research (LTRR was established in 1937 by A The University of Arizona (also referred to as UA, U of A, or Arizona) is a Land-grant and space-grant public institution Douglass sought to better understand cycles of sunspot activity and reasoned (correctly) that changes in solar activity would affect climate patterns on earth which would subsequently be recorded by tree-ring growth patterns (i. e. , sunspots → climate → tree rings). The technique of dendrochronology can date the tree rings in many types of wood to the exact calendar year each ring was formed.
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Growth rings
Growth rings, also referred to as tree rings or annual rings, can be seen in a horizontal cross section cut through the trunk of a tree. In Geometry, a cross section is the intersection of a body in 2-dimensional space with a line or of a body in 3-dimensional space with a plane etc In Botany, trunk (or bole) refers to the main structural member of a Tree that supports the Branches and is supported by and directly attached A tree is a perennial Woody plant. It is most often defined as a woody plant that has many secondary branches supported clear of the ground on a single main stem or Growth rings are the result of new growth in the vascular cambium, a lateral meristem, and are synonymous with secondary growth. The vascular cambium is a Lateral meristem in the Vascular tissue of plants A meristem is a tissue in all Plants consisting of undifferentiated cells ( meristematic cells) and found in zones of the plant where growth can take place In many Vascular plants, secondary growth is the result of the activity of the Vascular cambium. Visible rings result from the change in growth speed through the seasons of the year, thus one ring usually marks the passage of one year in the life of the tree. A season is one of the major divisions of the Year, generally based on yearly periodic changes in Weather. The rings are more visible in temperate zones, where the seasons differ more markedly.
The inner portion of a growth ring is formed early in the growing season, when growth is comparatively rapid (hence the wood is less dense) and is known as "early wood" or "spring wood" or "late-spring wood". The outer portion is the "late wood" (and has sometimes been termed "summer wood", often being produced in the summer, though sometimes in the autumn) and is more dense. "Early wood" is used in preference to "spring wood", as the latter term may not correspond to that time of year in climates where early wood is formed in the early summer (e. g. Canada) or in autumn, as in some Mediterranean species. Country to "Dominion of Canada" or "Canadian Federation" or anything else please read the Talk Page The Mediterranean Basin refers to the lands around and surrounded by the Mediterranean Sea.
In trees like white pines there is not much contrast in the different parts of the ring, and as a result the wood is very uniform in texture and can be said to have a mild grain (visually).
Many trees in temperate zones make one growth ring each year, with the newest adjacent to the bark. Cheraw (officially tʃʌrɔː chuh-raw often also /ʃʌrɔː/ shuh-raw) is a town in Chesterfield County, South Carolina, United States A tree is a perennial Woody plant. It is most often defined as a woody plant that has many secondary branches supported clear of the ground on a single main stem or For the entire period of a tree's life, a year-by-year record or ring pattern is formed that reflects the climatic conditions in which the tree grew. Adequate moisture and a long growing season result in a wide ring. A drought year may result in a very narrow one. Alternating poor and favorable conditions, such as mid summer droughts, can result in several rings forming in a given year. Trees from the same region will tend to develop the same patterns of ring widths for a given period. These patterns can be compared and matched ring for ring with trees growing in the same geographical zone and under similar climatic conditions. Following these tree-ring patterns from living trees back through time, chronologies can be built up, both for entire regions, and for sub-regions of the world. Thus wood from ancient structures can be matched to known chronologies (a technique called cross-dating) and the age of the wood determined precisely. Cross-dating was originally done by visual inspection. Nowadays, computers do the statistical matching.
To eliminate individual variations in tree ring growth, dendrochronologists take the smoothed average of the tree ring widths of multiple tree samples to build up a ring history. This process is termed replication. A tree ring history whose beginning and end dates are not known is called a floating chronology. It can be anchored by cross-matching either the beginning or the end section against the end sections of another chronology (tree ring history) whose dates are known. Fully anchored chronologies which extend back more than 10,000 years exist for river oak trees from South Germany (from the Main and Rhine rivers). The Main (maɪn is a River in Germany, 524 km (329 miles long (including White Main 574 km (357 mi and it is one of the more significant tributaries The Rhine (Rhein Rijn Rhin Reno Rain Rhenus is one of the longest and most important Rivers in Europe at 1320 kilometres (820 mi with an average discharge [1][2] Another fully anchored chronology which extends back 8500 years exists for the bristlecone pine in the Southwest US (White Mountains of California). The Southwestern area of the United States could be defined as the states west of the Mississippi River, with the qualification of a certain northern limit such as the 37 The White Mountains of California are a triangular fault block Mountain range facing the Sierra Nevada across the upper Owens Valley [3] Furthermore, the mutual consistency of these two independent dendrochronological sequences has been confirmed by comparing their radiocarbon and dendrochronological ages. [4] In 2004 a new calibration curve INTCAL04 was internationally ratified for calibrated dates back to 26,000 Before Present (BP) based on an agreed worldwide data set of trees and marine sediments. Before Present (BP years are a time scale used in Archaeology, Geology, and other scientific disciplines to specify when events in the past occurred [5]
Sampling and dating
Timber core samples measure the width of annual growth rings. By taking samples from different sites and different strata within a particular region, researchers can build a comprehensive historical sequence that becomes a part of the scientific record; for example, ancient timbers found in buildings can be dated to give an indication of when the source tree was alive and growing, setting an upper limit on the age of the wood. In Geology and related fields a stratum (plural strata) is a layer of rock or Soil with internally consistent characteristics that distinguishes Some genera of trees are more suitable than others for this type of analysis. Likewise, in areas where trees grew in marginal conditions such as aridity or semi-aridity, the techniques of dendrochronology are more consistent than in humid areas. These tools have been important in archaeological dating of timbers of the cliff dwellings of Native Americans in the arid Southwest. Native Americans in the United States are the indigenous peoples from the regions of North America now encompassed by the continental United States
A benefit of dendrochronology is that it makes available specimens of once-living material accurately dated to a specific year to be used as a calibration and check of radiocarbon dating, through the estimation of a date range formed through the interception of radiocarbon (BP, or 'B'efore 'P'resent, where present equals 1950-01-01) and calendar years. Calibration is the process of establishing the relationship between a measuring device and the units of measure Radiocarbon dating is a Radiometric dating method that uses the naturally occurring Radioisotope Carbon-14 (14C to determine the age of Before Present (BP years are a time scale used in Archaeology, Geology, and other scientific disciplines to specify when events in the past occurred Year 1950 ( MCML) was a Common year starting on Sunday (link will display the full calendar of the Gregorian calendar. New Year See also New Year The Ancient Romans began their consular year on January 1st since 153 BC [6] The bristlecone pine, being exceptionally long-lived and slow growing, has been used for this purpose, with still-living and dead specimens providing tree ring patterns going back thousands of years. The bristlecone pines are a small group of Pine trees (Family Pinaceae, genus Pinus, subsection Balfourianae) that are thought to In some regions dating sequences of more than 10,000 years are available. [7]
The dendrochronologist faces many obstacles, however, including some species of ant which inhabit trees and extend their galleries into the wood, thus destroying ring structure. In Biology, a species is one of the basic units of Biological classification and a Taxonomic rank. Ants are social Insects of the family Formicidae and along with the related families of Wasps and Bees belong to the order A tree is a perennial Woody plant. It is most often defined as a woody plant that has many secondary branches supported clear of the ground on a single main stem or
Similar seasonal patterns also occur in ice cores and in varves (layers of sediment deposition in a lake, river, or sea bed). An ice core is a Core sample from the accumulation of snow and ice over many years that have re-crystallized and have trapped air bubbles from previous time periods A varve is an annual layer of Sediment or Sedimentary rock. The word 'varve' is derived from the Swedish word varv whose Sediment is any particulate matter that can be transported by fluid flow and which eventually is deposited as a layer of solid particles on the bed or bottom of a body of The deposition pattern in the core will vary for a frozen-over lake versus an ice-free lake,and with the fineness of the sediment. These are used for dating in a manner similar to dendrochronology, and such techniques are used in combination with dendrochronology, to plug gaps and to extend the range of the seasonal data available to archaeologists.
While archaeologists can use the technique to date the piece of wood and when it was felled, it may be difficult to definitively determine the age of a building or structure that the wood is in. The wood could have been reused from an older structure, may have been felled and left for many years before use, or could have been used to replace a damaged piece of wood.
Applications
European chronologies derived from wooden structures found it difficult to bridge the gap in the 14th century when there was a building hiatus which coincided with the Black Death. The Black Death, or the Black Plague, was one of the deadliest Pandemics in human history widely thought to have been caused by a bacterium named Yersinia [8] Other plagues which were less well recorded also appear in the record.
In areas where the climate is reasonably predictable, trees develop annual rings of different properties depending on weather, rain, temperature, etc. Climate encompasses the temperatures humidity rainfall atmospheric particle count and numerous other meteorogical factors in a given region over long periods of The weather is a set of all the phenomena occurring in a given Atmosphere at a given Time. Rain is Liquid precipitation. On Earth it is the condensation of atmospheric Water vapor into drops heavy enough to fall often making it to Temperature is a physical property of a system that underlies the common notions of hot and cold something that is hotter generally has the greater temperature in different years. These variations may be used to infer past climate variations.
Given a sample of wood, the variation of the tree ring growths provides not only a match by year, it can also match location because the climate across Europe is not consistent. This makes it possible to determine the source of ships as well as smaller artifacts made from wood but which were transported long distances.
See also
References
- ^ Friedrich M, Remmele S, Kromer B, Hofmann J, Spurk M, Kaiser KF, Orcel C, Küppers M (2004). Dendroclimatology is the science of determining past Climates from Trees (primarily Tree rings) Dendroarchaeology is the study of old buildings or Artifacts using the techniques of Dendrochronology ( Tree -ring dating Paleoclimatology (also Palaeoclimatology) is the study of Climate change taken on the scale of the entire History of Earth. In Archaeology once the Archaeological record of given site has been excavated or collected from surface surveys it is necessary to gain as much data as possible and organize A varve is an annual layer of Sediment or Sedimentary rock. The word 'varve' is derived from the Swedish word varv whose "The 12,460-year Hohenheim oak and pine tree-ring chronology from central Europe - A unique annual record for radiocarbon calibration and paleoenvironment reconstructions". Radiocarbon 46: 1111–1122.
- ^ Pilcher JR, et al (1984). "A 7,272-year tree-ring chronology for western Europe". Nature 312: 150–152. doi:. A digital object identifier ( DOI) is a permanent identifier given to an Electronic document.
- ^ Ferguson CW, Graybill DA (1983). "Dendrochronology of Bristlecone Pine: A Progress Report". Radiocarbon 25: 287–288.
- ^ Stuiver Minze, Kromer Bernd, Becker Bernd, Ferguson CW (1986). "Radiocarbon Age Calibration back to 13,300 Years BP and the 14C Age Matching of the German Oak and US Bristlecone Pine Chronologies". Radiocarbon 28 (2): 969–979. ISSN 0033-8222. An International Standard Serial Number ( ISSN) is a unique eight-digit number used to identify a print or electronic Periodical publication.
- ^ Reimer Paula J, Baillie Mike GL, Bard Edouard, Bayliss Alex, Beck J Warren, Bertrand Chanda JH, Blackwell Paul G, Buck Caitlin E, Burr George S, Cutler Kirsten B, Damon Paul E, Edwards R Lawrence, Fairbanks Richard G, Friedrich Michael, Guilderson Thomas P, Hogg Alan G, Hughen Konrad, Kromer Bernd, McCormac Gerry, Manning Sturt, Ramsey Christopher Bronk, Reimer Ron W, Remmele Sabine, Southon John R, Stuiver Minze, Talamo Sahra, Taylor FW, van der Plicht Johannes, Weyhenmeyer Constanze E (2004). "INTCAL04 Terestrial Radiocarbon age calibration, 0–26 cal kyr BP" (PDF). Radiocarbon 46 (3): 1029–1058.
- ^ Renfre Colin, Bahn Paul (2004). Archaeology: Theories, Methods and Practice, Fourth Edition, 144-145. ISBN 0-500-28441-5.
- ^ Bibliography of Dendrochronology. ETH Forest Snow and Landscape Research. Retrieved on 2007-05-15. Year 2007 ( MMVII) was a Common year starting on Monday of the Gregorian calendar in the 21st century. Events 1252 - Pope Innocent IV issues the Papal bull Ad exstirpanda, which authorizes but also limits the
- ^ Baillie Mike (1997). A Slice Through Time, 124. ISBN 978-0713476545.
External links
- Henri D. Grissino-Mayer's Ultimate Tree Ring Web Pages
- The Laboratory of Tree-Ring Research
- Wiener Laboratory for Aegean and Near Eastern Dendrochronology at Cornell University
- University of Tennessee Dendrochronology
- Oxford Dendrochronology Laboratory
- University of Victoria Tree Ring Laboratory
- WST Online Glossary of Dendrochronology at ETH Zurich
- Mount Allison University Dendrochronology Laboratory
- Linda Brubaker, UW professor of dendrochronology, shows how dendrochronological research helps us reconstruct prior climate conditions and advance our knowledge of the effects of global climate change
- Nottingham Tree-Ring Dating Laboratory
- Laboratorio de Dendrocronología Universidad Austral de Chile, Valdivia
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