This is calculated by first deriving the probability of achieving an observed correlation coefficient from a single matching experiment, and then allowing for the fact that, when two series are compared at many overlap positions, a multitude of tests is performed.The best match (lowest value) can be compared to other matches as an additional means of assessing cross-dating strength.By counting the dark ring segments, scientists can tell a tree’s age if the cross section of the trunk is complete. Based at the University of Arizona in Tucson, Douglass wanted to know how sun spot activity affected climate, and his research soon led him to pioneering tree-ring analysis.The danger in attempting to date samples with relatively few rings, regardless of how the data are treated, is emphasized by these results.
Since cross-dating depends on matching the high-frequency elements of a sample against a master chronology, various methods are explored for removing the low-frequency variance in ring-width series before they are compared.The results show that a range of such “pre-whitening” methods can usefully be employed, and no single method is universally superior.Archaeologists sometimes study the ring patterns in beams or other pieces of wood from archaeological sites to help date the sites; they may also study the ring patterns to infer the local climatic history.Tree-ring analysis requires observation and pattern recognition.
This results in the cambium cells becoming smaller and thicker-walled.
By winter, when the sap finally stops flowing, a smooth dark ring marks the end of the tree’s annual growth.