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Where ancient buildings incorporated wooden beams, like Chaco Canyon’s Great Houses, dendrochronology—the science of tree ring dating—can help us accurately place these structures in history.Dendrochronology (from dendron, meaning “tree limb,” and khronos, meaning “time”) can be used to date wooden objects based upon an analysis of tree rings.Charlotte Pearson, a dendroarchaeologist and associate director of the University of Arizona’s Center for Mediterranean Archaeology and the Environment, prepares a sample of charcoal from Turkey for carbon dating at the UA’s Laboratory of Tree-Ring Research.A photo of a shipwreck, buried in silt for centuries and containing cargo in unbroken ceramic vessels, drew the only gasps at a recent seminar on the archaeology of the Mediterranean at the University of Arizona.One of the pressing questions archaeologists face is how to place an ancient structure on a historical timeline.

Scientists have explored Chaco Canyon for more than 100 years, making it one of the best-known archaeological sites in the world. Lekson, “Its ruins represent a decisive time and place in the history of ‘Anasazi,’ or Ancestral Pueblo peoples.”* Who these ancestral peoples were and what they accomplished has been the subject of much study, including research sponsored by Western National Parks Association.But only recently have scientists accumulated enough wood samples and other evidence from bogs, ice layers, medieval ruins, ancient campfires and many other sources to extend dendrochronology to objects almost as old as the last Ice Age. Baillie of Queen's University, Belfast, and his colleagues expect to determine the exact date of a neolithic roadway in Somerset, England. 541 - almost perfectly match the years for which eruptions were also detected in the rings of North American bristlecone pines and in thin layers of acidic ice within the Greenland ice cap. On an ice cap, it is embedded in an ice layer that is gradually covered by successive layers of non-acidic ice.New understanding of the significance of tree rings has also allowed scientists to calibrate other less precise techniques for determining the ages of objects, thereby making the entire field of age determination more reliable and accurate. Kuniholm of Cornell University extracted tree-ring samples from the cedar planking of a boat built in Egypt in the 16th century B. The boat, owned by the Carnegie Museum in Pittsburgh, is believed to have been built while Egypt was ruled by the Hyksos ''shepherd'' kings, a time when few written records were kept, Dr. The tree-ring dating techniques he plans to apply to the samples may help archeologists sort out the detailed chronology of the Hyksos period. The wooden trackway, known as Sweet Track, was laid across a marsh around 3800 B. By drilling through the layers and measuring their acidity, scientists can estimate how long ago any given eruption may have spread acid rain over the earth.For the entire period of a tree’s life, a year-by-year record or ring pattern is formed that in some way reflects the climatic and environmental condition in which the tree grew.Thus, dendrochronology measures, compares and matches tree-ring growth, offering invaluable information on the age of the wood used by builders and artists and can help to date buildings, wooden objects and works of art such as icons.

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