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Dendrochronology (or tree-ring dating) is the
scientific method The scientific method is an Empirical evidence, empirical method for acquiring knowledge that has been referred to while doing science since at least the 17th century. Historically, it was developed through the centuries from the ancient and ...
of
dating Dating is a stage of Romance (love), romantic relationships in which individuals engage in activity together, often with the intention of evaluating each other's suitability as a partner in a future intimate relationship. It falls into the cate ...
tree rings (also called growth rings) to the exact year they were formed in a tree. As well as dating them, this can give data for
dendroclimatology Dendroclimatology is the science of determining past climates from trees (primarily properties of the annual tree rings). Tree rings are wider when conditions favor growth, narrower when times are difficult. Other properties of the annual rings, ...
, the study of climate and atmospheric conditions during different periods in history from the wood of old trees. Dendrochronology derives from the Ancient Greek (), meaning "tree", (), meaning "time", and (), "the study of". Dendrochronology is useful for determining the precise age of samples, especially those that are too recent for
radiocarbon dating Radiocarbon dating (also referred to as carbon dating or carbon-14 dating) is a method for Chronological dating, determining the age of an object containing organic material by using the properties of carbon-14, radiocarbon, a radioactive Isotop ...
, which always produces a range rather than an exact date. However, for a precise date of the death of the tree a full sample to the edge is needed, which most trimmed timber will not provide. It also gives data on the timing of events and rates of change in the environment (most prominently climate) and also in wood found in
archaeology Archaeology or archeology is the study of human activity through the recovery and analysis of material culture. The archaeological record consists of Artifact (archaeology), artifacts, architecture, biofact (archaeology), biofacts or ecofacts, ...
or works of art and architecture, such as old
panel painting A panel painting is a painting made on a flat panel of wood, either a single piece or a number of pieces joined together. Until canvas became the more popular support medium in the 16th century, panel painting was the normal method, when not pain ...
s. It is also used as a check in radiocarbon dating to calibrate radiocarbon ages. New growth in
tree In botany, a tree is a perennial plant with an elongated stem, or trunk, usually supporting branches and leaves. In some usages, the definition of a tree may be narrower, e.g., including only woody plants with secondary growth, only ...
s occurs in a layer of cells near the bark. A tree's growth rate changes in a predictable pattern throughout the year in response to seasonal climate changes, resulting in visible growth rings. Each ring marks a complete cycle of
season A season is a division of the year based on changes in weather, ecology, and the number of daylight hours in a given region. On Earth, seasons are the result of the axial parallelism of Earth's axial tilt, tilted orbit around the Sun. In temperat ...
s, or one year, in the tree's life. As of 2023, securely dated tree-ring data for Germany, Bohemia and Ireland are available going back 13,910 years. A new method is based on measuring variations in oxygen isotopes in each ring, and this 'isotope dendrochronology' can yield results on samples which are not suitable for traditional dendrochronology due to too few or too similar rings. Some regions have "floating sequences", with gaps which mean that earlier periods can only be approximately dated. As of 2024, only three areas have continuous sequences going back to prehistoric times, the foothills of the Northern Alps, the southwestern United States and the British Isles.
Miyake event A Miyake event is an observed sharp enhancement of the production of Cosmogenic nuclide, cosmogenic isotopes by cosmic rays. It can be marked by a spike in the concentration of radioactive carbon isotope Carbon-14, in tree rings, as well as Beryl ...
s, which are major spikes in
cosmic rays Cosmic rays or astroparticles are high-energy particles or clusters of particles (primarily represented by protons or atomic nuclei) that move through space at nearly the speed of light. They originate from the Sun, from outside of the Solar ...
at known dates, are visible in trees rings and can fix the dating of a floating sequence.


History

The Greek botanist
Theophrastus Theophrastus (; ; c. 371 – c. 287 BC) was an ancient Greek Philosophy, philosopher and Natural history, naturalist. A native of Eresos in Lesbos, he was Aristotle's close colleague and successor as head of the Lyceum (classical), Lyceum, the ...
(c. 371 – c. 287 BC) first mentioned that the wood of trees has rings. In his 1651 ''
Trattato della Pittura ''A Treatise on Painting'' (''Trattato della pittura'') is a collection of Leonardo da Vinci's writings entered in his notebooks under the general heading "On Painting". The manuscripts were begun in Milan while Leonardo was under the service of ...
'' (Treatise on Painting),
Leonardo da Vinci Leonardo di ser Piero da Vinci (15 April 1452 - 2 May 1519) was an Italian polymath of the High Renaissance who was active as a painter, draughtsman, engineer, scientist, theorist, sculptor, and architect. While his fame initially rested o ...
(1452–1519) was the first person to mention that trees form rings annually and that their thickness is determined by the conditions under which they grew. In 1737, French investigators
Henri-Louis Duhamel du Monceau Henri-Louis Duhamel du Monceau (; 20 July 170013 August 1782) was a French physician, naval engineer and botanist. Biography Henri-Louis Duhamel du Monceau was born in Paris in 1700, the son of Alexandre Duhamel, lord of Denainvilliers. I ...
and
Georges-Louis Leclerc de Buffon Georges-Louis Leclerc, Comte de Buffon (; 7 September 1707 – 16 April 1788) was a French Natural history, naturalist, mathematician, and cosmology, cosmologist. He held the position of ''intendant'' (director) at the ''Jardin du Roi'', now ca ...
examined the effect of growing conditions on the shape of tree rings. They found that in 1709, a severe winter produced a distinctly dark tree ring, which served as a reference for subsequent European naturalists. In the U.S.,
Alexander Catlin Twining Alexander Catlin Twining (July 5, 1801 – November 22, 1884) was an American scientist and inventor. Twining, the son of Stephen Twining and Almira (Catlin) Twining, was born in New Haven, Connecticut, July 5, 1801. He graduated from Yale Col ...
(1801–1884) suggested in 1833 that patterns among tree rings could be used to synchronize the dendrochronology of various trees and thereby to reconstruct past climates across entire regions. The English polymath
Charles Babbage Charles Babbage (; 26 December 1791 – 18 October 1871) was an English polymath. A mathematician, philosopher, inventor and mechanical engineer, Babbage originated the concept of a digital programmable computer. Babbage is considered ...
proposed using dendrochronology to date the remains of trees in peat bogs or even in geological strata (1835, 1838). During the latter half of the nineteenth century, the scientific study of tree rings and the application of dendrochronology began. In 1859, the German-American Jacob Kuechler (1823–1893) used crossdating to examine
oak An oak is a hardwood tree or shrub in the genus ''Quercus'' of the beech family. They have spirally arranged leaves, often with lobed edges, and a nut called an acorn, borne within a cup. The genus is widely distributed in the Northern Hemisp ...
s (''
Quercus stellata ''Quercus stellata'', the post oak or iron oak, is a North American species of oak in the white oak section. It is a slow-growing oak that lives in dry areas on the edges of fields, tops of ridges, and also grows in poor soils, and is resistan ...
'') in order to study the record of climate in western Texas. In 1866, the German botanist, entomologist, and forester
Julius Theodor Christian Ratzeburg Julius Theodor Christian Ratzeburg (16 February 1801– 24 October 1871) was a German zoology, zoologist, botany, botanist, entomology, entomologist, and forestry, forester. Biography Ratzeburg was born in Berlin, the son of a professor at th ...
(1801–1871) observed the effects on tree rings of defoliation caused by insect infestations. By 1882, this observation was already appearing in
forestry Forestry is the science and craft of creating, managing, planting, using, conserving and repairing forests and woodlands for associated resources for human and Natural environment, environmental benefits. Forestry is practiced in plantations and ...
textbooks. In the 1870s, the Dutch astronomer
Jacobus Kapteyn Jacobus Cornelius Kapteyn (19 January 1851 – 18 June 1922) was a Dutch astronomy, astronomer. He carried out extensive studies of the Milky Way. He found that the apparent movement of stars was not randomly distributed but had two preferentia ...
(1851–1922) was using crossdating to reconstruct the climates of the Netherlands and Germany. In 1881, the Swiss-Austrian forester Arthur von Seckendorff-Gudent (1845–1886) was using crossdating. From 1869 to 1901, Robert Hartig (1839–1901), a German professor of forest pathology, wrote a series of papers on the anatomy and ecology of tree rings. In 1892, the Russian physicist (1841–1905) wrote that he had used patterns found in tree rings to predict droughts in 1882 and 1891. During the first half of the twentieth century, the astronomer A. E. Douglass founded the Laboratory of Tree-Ring Research at the
University of Arizona The University of Arizona (Arizona, U of A, UArizona, or UA) is a Public university, public Land-grant university, land-grant research university in Tucson, Arizona, United States. Founded in 1885 by the 13th Arizona Territorial Legislature, it ...
. Douglass sought to better understand cycles of sunspot activity and reasoned that changes in
solar activity Solar phenomena are natural phenomena which occur within the Stellar atmosphere, atmosphere of the Sun. They take many forms, including solar wind, Solar radio emission, radio wave flux, solar flares, coronal mass ejections, Stellar corona#Coron ...
would affect climate patterns on earth, which would subsequently be recorded by tree-ring growth patterns (''i.e.'', sunspots → climate → tree rings).


Methods


Growth rings

Horizontal cross sections cut through the trunk of a
tree In botany, a tree is a perennial plant with an elongated stem, or trunk, usually supporting branches and leaves. In some usages, the definition of a tree may be narrower, e.g., including only woody plants with secondary growth, only ...
can reveal growth rings, also referred to as tree rings or annual rings. Growth rings result from new growth in the
vascular cambium The vascular cambium is the main growth tissue in the stems and roots of many plants exhibiting secondary growth, specifically in dicots such as buttercups and oak trees, gymnosperms such as pine trees, as well as in certain other vascular ...
, a layer of cells near the
bark Bark may refer to: Common meanings * Bark (botany), an outer layer of a woody plant such as a tree or stick * Bark (sound), a vocalization of some animals (which is commonly the dog) Arts and entertainment * ''Bark'' (Jefferson Airplane album), ...
that botanists classify as a lateral meristem; this growth in diameter is known as
secondary growth In botany, secondary growth is the growth that results from cell division in the cambia or lateral meristems and that causes the stems and roots to thicken, while primary growth is growth that occurs as a result of cell division at the tips ...
. Visible rings result from the change in growth speed through the
season A season is a division of the year based on changes in weather, ecology, and the number of daylight hours in a given region. On Earth, seasons are the result of the axial parallelism of Earth's axial tilt, tilted orbit around the Sun. In temperat ...
s of the year; thus, critical for the title method, one ring generally marks the passage of one year in the life of the tree. Removal of the bark of the tree in a particular area may cause deformation of the rings as the plant overgrows the scar. The rings are more visible in trees which have grown in
temperate zone In geography, the temperate climates of Earth occur in the middle latitudes (approximately 23.5° to 66.5° N/S of the Equator), which span between the tropics and the polar regions of Earth. These zones generally have wider temperature ra ...
s, where the seasons differ more markedly. The inner portion of a growth ring forms 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" (sometimes termed "summer wood", often being produced in the summer, though sometimes in the autumn) and is denser. Many trees in temperate zones produce one growth-ring each year, with the newest adjacent to the bark. Hence, for the entire period of a tree's life, a year-by-year record or ring pattern builds up that reflects the age of the tree and the climatic conditions in which the tree grew. Adequate moisture and a long growing season result in a wide ring, while a drought year may result in a very narrow one. Direct reading of tree ring chronologies is a complex science, for several reasons. First, contrary to the single-ring-per-year paradigm, alternating poor and favorable conditions, such as mid-summer droughts, can result in several rings forming in a given year. In addition, particular tree species may present "missing rings", and this influences the selection of trees for study of long time-spans. For instance, missing rings are rare in
oak An oak is a hardwood tree or shrub in the genus ''Quercus'' of the beech family. They have spirally arranged leaves, often with lobed edges, and a nut called an acorn, borne within a cup. The genus is widely distributed in the Northern Hemisp ...
and elm trees. Critical to the science, trees from the same region tend to develop the same patterns of ring widths for a given period of chronological study. Researchers can compare and match these patterns ring-for-ring with patterns from trees which have grown at the same time in the same geographical zone (and therefore under similar climatic conditions). When one can match these tree-ring patterns across successive trees in the same locale, in overlapping fashion, chronologies can be built up—both for entire geographical regions and for sub-regions. Moreover, wood from ancient structures with known chronologies can be matched to the tree-ring data (a technique called 'cross-dating'), and the age of the wood can thereby be determined precisely. Dendrochronologists originally carried out cross-dating by visual inspection; more recently, they have harnessed computers to do the task, applying statistical techniques to assess the 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', a process 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 a section against another chronology (tree-ring history) whose dates are known. A fully anchored and cross-matched chronology for oak and pine in central Europe extends back 12,460 years, and an oak chronology goes back 7,506 years in Bohemia, 7,429 years in Ireland and 6,939 years in
England England is a Countries of the United Kingdom, country that is part of the United Kingdom. It is located on the island of Great Britain, of which it covers about 62%, and List of islands of England, more than 100 smaller adjacent islands. It ...
. Comparison of radiocarbon and dendrochronological ages supports the consistency of these two independent dendrochronological sequences. Another fully anchored chronology that extends back 8,500 years exists for the bristlecone pine in the Southwest US ( White Mountains of California).


Dendrochronological equation

The dendrochronological equation defines the law of growth of tree rings. The equation was proposed by Russian biophysicist Alexandr N. Tetearing in his work "Theory of populations" in the form: \Delta L(t) = \frac \, \frac, where Δ''L'' is width of annual ring, ''t'' is time (in years), ''ρ'' is density of wood, ''kv'' is some coefficient, ''M''(''t'') is function of mass growth of the tree. Ignoring the natural sinusoidal oscillations in tree mass, the formula for the changes in the annual ring width is: \Delta L(t) = -\frac where ''c''1, ''c''2, and ''c''4 are some coefficients, ''a''1 and ''a''2 are positive constants. The formula is useful for correct approximation of samples data before data normalization procedure. The typical forms of the function Δ''L''(''t'') of annual growth of wood ring are shown in the figures.


Sampling and dating

Dendrochronology allows specimens of once-living material to be accurately dated to a specific year. Dates are often represented as estimated calendar years B.P., for before present, where "present" refers to 1 January 1950. Timber core samples are sampled and used to measure the width of annual growth rings; by taking samples from different sites within a particular region, researchers can build a comprehensive historical sequence. The techniques of dendrochronology are more consistent in areas where trees grew in marginal conditions such as aridity or semi-aridity where the ring growth is more sensitive to the environment, rather than in humid areas where tree-ring growth is more uniform (complacent). In addition, some genera of trees are more suitable than others for this type of analysis. For instance, the
bristlecone pine The term bristlecone pine covers three species of pine tree (family Pinaceae, genus ''Pinus'', subsection ''Balfourianae''). All three species are long-lived and highly resilient to harsh weather and bad soils. One of the three species, ''Pinus ...
is exceptionally long-lived and slow growing, and has been used extensively for chronologies; still-living and dead specimens of this species provide tree-ring patterns going back thousands of years, in some regions more than 10,000 years. Currently, the maximum span for fully anchored chronology is a little over 11,000 years B.P. IntCal20 is the 2020 "Radiocarbon Age Calibration Curve", which provides a calibrated carbon 14 dated sequence going back 55,000 years. The most recent part, going back 13,900 years, is based on tree rings.


Reference sequences

European chronologies derived from wooden structures initially found it difficult to bridge the gap in the fourteenth century when there was a building hiatus, which coincided with the
Black Death The Black Death was a bubonic plague pandemic that occurred in Europe from 1346 to 1353. It was one of the list of epidemics, most fatal pandemics in human history; as many as people perished, perhaps 50% of Europe's 14th century population. ...
. However, there do exist unbroken chronologies dating back to prehistoric times, for example the Danish chronology dating back to 352 BC. Given a sample of wood, the variation of the tree-ring growths not only provides a match by year, but can also match location because climate varies from place to place. This makes it possible to determine the source of ships as well as smaller artifacts made from wood, but which were transported long distances, such as panels for paintings and ship timbers.


Miyake events

Miyake event A Miyake event is an observed sharp enhancement of the production of Cosmogenic nuclide, cosmogenic isotopes by cosmic rays. It can be marked by a spike in the concentration of radioactive carbon isotope Carbon-14, in tree rings, as well as Beryl ...
s, such as the ones in 774–775 and 993–994, can provide fixed reference points in an unknown time sequence as they are due to cosmic radiation.Andrej Maczkowski et al, "Absolute dating of the European Neolithic using the 5259 BC rapid 14C excursion", Nature Communications, 2024 As they appear as spikes in carbon 14 in tree rings for that year all round the world, they can be used to date historical events to the year. For example, wooden houses in the
Viking Vikings were seafaring people originally from Scandinavia (present-day Denmark, Norway, and Sweden), who from the late 8th to the late 11th centuries raided, pirated, traded, and settled throughout parts of Europe.Roesdahl, pp. 9� ...
site at
L'Anse aux Meadows L'Anse aux Meadows () is an archaeological site, first excavated in the 1960s, of a Norse colonization of North America, Norse settlement dating to approximately 1,000 years ago. The site is located on the northernmost tip of the island of Newf ...
in Newfoundland were dated by finding the layer with the 993 spike, which showed that the wood is from a tree felled in 1021. Researchers at the University of Bern have provided exact dating of a floating sequence in a
Neolithic The Neolithic or New Stone Age (from Ancient Greek, Greek 'new' and 'stone') is an archaeological period, the final division of the Stone Age in Mesopotamia, Asia, Europe and Africa (c. 10,000 BCE to c. 2,000 BCE). It saw the Neolithic Revo ...
settlement in northern Greece by tying it to a spike in cosmogenic radiocarbon in 5259 BC.


Frost rings

Frost ring is a term used to designate a layer of deformed, collapsed
tracheid A tracheid is a long and tapered Lignin, lignified cell in the xylem of Tracheophyta, vascular plants. It is a type of conductive cell called a tracheary element. Angiosperms also use another type of conductive cell, called vessel elements, to t ...
s and traumatic
parenchyma upright=1.6, Lung parenchyma showing damage due to large subpleural bullae. Parenchyma () is the bulk of functional substance in an animal organ such as the brain or lungs, or a structure such as a tumour. In zoology, it is the tissue that ...
cells in tree ring analysis. They are formed when air temperature falls below freezing during a period of cambial activity. They can be used in dendrochronology to indicate years that are colder than usual.


Applications


Radiocarbon dating calibration

Dates from dendrochronology can be used as a calibration and check of
radiocarbon dating Radiocarbon dating (also referred to as carbon dating or carbon-14 dating) is a method for Chronological dating, determining the age of an object containing organic material by using the properties of carbon-14, radiocarbon, a radioactive Isotop ...
. This can be done by checking radiocarbon dates against long master sequences, with Californian bristle-cone pines in Arizona being used to develop this method of calibration as the longevity of the trees (up to c.4900 years) in addition to the use of dead samples meant a long, unbroken tree ring sequence could be developed (dating back to ). Additional studies of European oak trees, such as the master sequence in Germany that dates back to , can also be used to back up and further calibrate radiocarbon dates.


Climatology

Dendroclimatology Dendroclimatology is the science of determining past climates from trees (primarily properties of the annual tree rings). Tree rings are wider when conditions favor growth, narrower when times are difficult. Other properties of the annual rings, ...
is the science of determining past
climate Climate is the long-term weather pattern in a region, typically averaged over 30 years. More rigorously, it is the mean and variability of meteorological variables over a time spanning from months to millions of years. Some of the meteoro ...
s from
tree In botany, a tree is a perennial plant with an elongated stem, or trunk, usually supporting branches and leaves. In some usages, the definition of a tree may be narrower, e.g., including only woody plants with secondary growth, only ...
s primarily from the properties of the annual tree rings. Other properties of the annual rings, such as maximum latewood density (MXD) have been shown to be better proxies than simple ring width. Using tree rings, scientists have estimated many local climates for hundreds to thousands of years previous.


Art history

Dendrochronology has become important to art historians in the dating of
panel painting A panel painting is a painting made on a flat panel of wood, either a single piece or a number of pieces joined together. Until canvas became the more popular support medium in the 16th century, panel painting was the normal method, when not pain ...
s. However, unlike analysis of samples from buildings, which are typically sent to a laboratory, wooden supports for paintings usually have to be measured in a museum conservation department, which places limitations on the techniques that can be used. In addition to dating, dendrochronology can also provide information as to the source of the panel. Many
Early Netherlandish painting Early Netherlandish painting is the body of work by artists active in the Burgundian Netherlands, Burgundian and Habsburg Netherlands during the 15th- and 16th-century Northern Renaissance period, once known as the Flemish Primitives. It flour ...
s have turned out to be painted on panels of "Baltic oak" shipped from the
Vistula The Vistula (; ) is the longest river in Poland and the ninth-longest in Europe, at in length. Its drainage basin, extending into three other countries apart from Poland, covers , of which is in Poland. The Vistula rises at Barania Góra i ...
region via ports of the
Hanseatic League The Hanseatic League was a Middle Ages, medieval commercial and defensive network of merchant guilds and market towns in Central Europe, Central and Northern Europe, Northern Europe. Growing from a few Northern Germany, North German towns in the ...
. Oak panels were used in a number of northern countries such as
England England is a Countries of the United Kingdom, country that is part of the United Kingdom. It is located on the island of Great Britain, of which it covers about 62%, and List of islands of England, more than 100 smaller adjacent islands. It ...
,
France France, officially the French Republic, is a country located primarily in Western Europe. Overseas France, Its overseas regions and territories include French Guiana in South America, Saint Pierre and Miquelon in the Atlantic Ocean#North Atlan ...
and
Germany Germany, officially the Federal Republic of Germany, is a country in Central Europe. It lies between the Baltic Sea and the North Sea to the north and the Alps to the south. Its sixteen States of Germany, constituent states have a total popu ...
. Wooden supports other than oak were rarely used by Netherlandish painters. Since panels of seasoned wood were used, an uncertain number of years has to be allowed for seasoning when estimating dates. Panels were trimmed of the outer rings, and often each panel only uses a small part of the
radius In classical geometry, a radius (: radii or radiuses) of a circle or sphere is any of the line segments from its Centre (geometry), center to its perimeter, and in more modern usage, it is also their length. The radius of a regular polygon is th ...
of the trunk. Consequently, dating studies usually result in a '' terminus post quem'' (earliest possible) date, and a tentative date for the arrival of a seasoned raw panel using assumptions as to these factors. As a result of establishing numerous sequences, it was possible to date 85–90% of the 250 paintings from the fourteenth to seventeenth century analysed between 1971 and 1982; by now a much greater number have been analysed. A portrait of
Mary, Queen of Scots Mary, Queen of Scots (8 December 1542 – 8 February 1587), also known as Mary Stuart or Mary I of Scotland, was List of Scottish monarchs, Queen of Scotland from 14 December 1542 until her forced abdication in 1567. The only surviving legit ...
in the
National Portrait Gallery, London The National Portrait Gallery (NPG) is an art gallery in London that houses a collection of portraits of historically important and famous British people. When it opened in 1856, it was arguably the first national public gallery in the world th ...
was believed to be an eighteenth-century copy. However, dendrochronology revealed that the wood dated from the second half of the sixteenth century. It is now regarded as an original sixteenth-century painting by an unknown artist. On the other hand, dendrochronology was applied to four paintings depicting the same subject, that of Christ expelling the money-lenders from the Temple. The results showed that the age of the wood was too late for any of them to have been painted by
Hieronymus Bosch Hieronymus Bosch (; ; born Jheronimus van Aken ;  – 9 August 1516) was a Dutch people, Dutch painter from Duchy of Brabant, Brabant. He is one of the most notable representatives of the Early Netherlandish painting school. His work, gene ...
. While dendrochronology has become an important tool for dating oak panels, it is not effective in dating the poplar panels often used by Italian painters because of the erratic growth rings in poplar. The sixteenth century saw a gradual replacement of wooden panels by canvas as the support for paintings, which means the technique is less often applicable to later paintings. In addition, many panel paintings were transferred onto canvas or other supports during the nineteenth and twentieth centuries.


Archaeology

The dating of buildings with wooden structures and components is also done by dendrochronology; dendroarchaeology is the term for the application of dendrochronology in archaeology. While archaeologists can date wood and when it was felled, it may be difficult to definitively determine the age of a building or structure in which the wood was used; 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. The dating of building via dendrochronology thus requires knowledge of the history of building technology. Many prehistoric forms of buildings used "posts" that were whole young tree trunks; where the bottom of the post has survived in the ground these can be especially useful for dating. Examples: * The
Post Track The Post Track is an ancient causeway in the valley of the River Brue on the Somerset Levels, England. It dates from around 3838 BCE, making it some 30 years older than the Sweet Track in the same area. Various sections have been scheduled ...
and
Sweet Track The Sweet Track is an ancient trackway, or causeway, in the Somerset Levels, England, named after its finder, Ray Sweet. It was built in 3807 BC (determined using dendrochronology – tree-ring dating) and is the second-oldest timber track ...
, ancient timber trackways in the
Somerset levels The Somerset Levels are a coastal plain and wetland area of Somerset, England, running south from the Mendips to the Blackdown Hills. The Somerset Levels have an area of about and are bisected by the Polden Hills; the areas to the south ...
,
England England is a Countries of the United Kingdom, country that is part of the United Kingdom. It is located on the island of Great Britain, of which it covers about 62%, and List of islands of England, more than 100 smaller adjacent islands. It ...
, have been dated to 3838 BC and 3807 BC. * Navan Fort where in
Prehistoric Ireland The prehistory of Ireland has been pieced together from Archaeology, archaeological evidence, which has grown at an increasing rate over recent decades. It begins with the first evidence of permanent human residence in Ireland around 10,500 BC ...
a large structure was built with more than two hundred posts. The central oak post was felled in 95 BC. * The Fairbanks House in Dedham, Massachusetts. While the house had long been claimed to have been built (and being the oldest wood-framed house in North America), core samples of wood taken from a summer beam confirmed the wood was from an oak tree felled in 1637–8, as wood was not seasoned before use in building at that time in
New England New England is a region consisting of six states in the Northeastern United States: Connecticut, Maine, Massachusetts, New Hampshire, Rhode Island, and Vermont. It is bordered by the state of New York (state), New York to the west and by the ...
. An additional sample from another beam yielded a date of 1641, thus confirming the house had been constructed starting in 1638 and finished sometime after 1641 . * The burial chamber of
Gorm the Old Gorm the Old (; ; ), also called Gorm the Languid (), was List of Danish monarchs, ruler of Denmark, reigning from to his death or a few years later.Lund, N. (2020), p. 147
, who died c. 958, was constructed from wood of timbers felled in 958. *
Veliky Novgorod Veliky Novgorod ( ; , ; ), also known simply as Novgorod (), is the largest city and administrative centre of Novgorod Oblast, Russia. It is one of the oldest cities in Russia, being first mentioned in the 9th century. The city lies along the ...
, where, between the tenth and the fifteenth century, numerous consecutive layers of wooden log pavement have been placed over the accumulating dirt. * The
Neolithic The Neolithic or New Stone Age (from Ancient Greek, Greek 'new' and 'stone') is an archaeological period, the final division of the Stone Age in Mesopotamia, Asia, Europe and Africa (c. 10,000 BCE to c. 2,000 BCE). It saw the Neolithic Revo ...
well with linings made of oak wood, found near Ostrov,
Czech Republic The Czech Republic, also known as Czechia, and historically known as Bohemia, is a landlocked country in Central Europe. The country is bordered by Austria to the south, Germany to the west, Poland to the northeast, and Slovakia to the south ...
, have been dated to 5,482-5,243 BC.


Measurement platforms, software, and data formats

There are many different file formats used to store tree ring width data. Effort for standardisation was made with the development of TRiDaS. Further development led to the database software Tellervo, which is based on the new standard format whilst being able to import lots of different data formats. The desktop application can be attached to measurement devices and works with the database server that is installed separately.


Continuous sequence

Bard et al write in 2023: "The oldest tree-ring series are known as floating since, while their constituent rings can be counted to create a relative internal chronology, they cannot be dendro-matched with the main Holocene absolute chronology. However, 14C analyses performed at high resolution on overlapped absolute and floating tree-rings series enable one to link them almost absolutely and hence to extend the calibration on annual tree rings until ≈13 900 cal yr BP."


Related chronologies

Herbchronology is the analysis of annual
growth rings Dendrochronology (or tree-ring dating) is the scientific method of chronological dating, dating tree rings (also called growth rings) to the exact year they were formed in a tree. As well as dating them, this can give data for dendroclimatology, ...
(or simply annual rings) in the secondary root
xylem Xylem is one of the two types of transport tissue (biology), tissue in vascular plants, the other being phloem; both of these are part of the vascular bundle. The basic function of the xylem is to transport water upward from the roots to parts o ...
of
perennial In horticulture, the term perennial ('' per-'' + '' -ennial'', "through the year") is used to differentiate a plant from shorter-lived annuals and biennials. It has thus been defined as a plant that lives more than 2 years. The term is also ...
herbaceous plants Herbaceous plants are vascular plants that have no persistent wood, woody stems above ground. This broad category of plants includes many perennial plant, perennials, and nearly all Annual plant, annuals and Biennial plant, biennials. Definition ...
. Similar seasonal patterns also occur in
ice core An ice core is a core sample that is typically removed from an ice sheet or a high mountain glacier A glacier (; or ) is a persistent body of dense ice, a form of rock, that is constantly moving downhill under its own weight. A glacier ...
s and in varves (layers of
sediment Sediment is a solid material that is transported to a new location where it is deposited. It occurs naturally and, through the processes of weathering and erosion, is broken down and subsequently sediment transport, transported by the action of ...
deposition in a lake, river, or sea bed). 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.
Sclerochronology Sclerochronology is the study of periodic physical and chemical features in the hard tissues of animals that grow by accretion, including invertebrates and coralline red algae, and the temporal context in which they formed. It is particularly usefu ...
is the study of
algae Algae ( , ; : alga ) is an informal term for any organisms of a large and diverse group of photosynthesis, photosynthetic organisms that are not plants, and includes species from multiple distinct clades. Such organisms range from unicellular ...
deposits. Some columnar
cacti A cactus (: cacti, cactuses, or less commonly, cactus) is a member of the plant family Cactaceae (), a family of the order Caryophyllales comprising about 127 genera with some 1,750 known species. The word ''cactus'' derives, through Latin, ...
also exhibit similar seasonal patterns in the isotopes of carbon and oxygen in their spines (
acanthochronology Acanthochronology is the study of cactus Thorns, spines, and prickles, spines or ''Euphorbia'' Thorns, spines, and prickles, thorns grown in time ordered sequence (i.e. in series). Physical, morphological or chemical characteristics and information ...
). 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 and paleoclimatologists. A similar technique is used to estimate the age of fish stocks through the analysis of growth rings in the
otolith An otolith (, ' ear + , ', a stone), also called otoconium, statolith, or statoconium, is a calcium carbonate structure in the saccule or utricle (ear), utricle of the inner ear, specifically in the vestibular system of vertebrates. The saccule ...
bones.


See also

* Dendrology * International Tree-Ring Data Bank *
Post excavation Post-excavation analysis constitutes processes that are used to study archaeological materials after an excavation is completed. Since the advent of "New Archaeology" in the 1960s, the use of scientific techniques in archaeology has grown in impo ...
* Timeline of dendrochronology timestamp events


References


External links


Nottingham Tree-Ring Dating Laboratory

Oxford Tree-Ring Laboratory

''Dendrochronology and Art History of Painted Ceilings'' (Historic Environment Scotland, 2017).

Video & commentary on medullary rays, heart wood, and tree rings.

Video & commentary on Tree Rings – Formation and Purpose

Bibliography of Dendrochronology

Multilingual Glossary of Dendrochronology

Digital Collaboratory for Cultural Dendrochronology (DCCD)



Laboratory of Tree-Ring Research University of Arizona


the academic site of Prof. Henri D. Grissino-Mayer, Department of Geography, The University of Tennessee, and the Laboratory of Tree-Ring Science * {{Authority control American inventions Art history Conservation and restoration of cultural heritage Dating methods Dendrology Incremental dating Paleoecology