A major landmark in dendrochronology was reported last month in the British journal Nature by Dr. The Belfast scientist reported that traces of at least five major eruptions in prehistoric or ancient times are clearly visible in the rings of Irish oaks that grew over the last 7,272 years. Moreover, scientists in the United States and Ireland have discovered how to use tree-ring chronologies to greatly enhance the precision of carbon dating in determining the ages of organic objects by their radioactivity. Gordon Pearson of Queen's College, Belfast, and Dr.Minsi Stuiver of the University of Washington, Seattle, have independently discovered an important relationship between the true age of a wooden object and its apparent age as determined by carbon dating.BP stands for “Before Present” or “Before Physics” as some would refer to it.It should be noted that a BP notation is also used in other dating techniques but is defined differently, as in the case of thermoluminescence dating wherein BP is defined as AD 1980.Archeologists are quickly putting the new knowledge to practical use. In Europe and the Middle East archeologists have started scores of new tree-ring dating projects. C., but with the help of tree rings, the scientists expect to determine the exact years in which its trees were felled. Erupting volcanoes also create dust veils that circle the planet, reducing sunlight and chilling the climate.Tree rings have also provided geologists and climatologists with a new tool for answering some old questions. In North America, this has caused brief periods of frost damage to pine trees, and such damage can be seen in a tree ring representing a single cold year.Calibration is not only done before an analysis but also on analytical results as in the case of radiocarbon dating—an analytical method that identifies the age of a material that once formed part of the biosphere by determining its carbon-14 content and tracing its age by its radioactive decay.
During the latter half of the nineteenth century, the scientific study of tree rings and the application of dendrochronology began.Results of carbon-14 dating are reported in radiocarbon years, and calibration is needed to convert radiocarbon years into calendar years.Uncalibrated radiocarbon measurements are usually reported in years BP where 0 (zero) BP is defined as AD 1950.It has a radio half-life (T 1/2) of 5,730 years and is a low energy beta emitter with a radioactive range in air of ten inches.It is produced currently at a fairly constant rate in the upper atmosphere through the action of cosmic radiation on Nitrogen-14.