What is tree ring cross dating
I’m coming to learn at the Tree Ring Laboratory of Lamont-Doherty Earth Observatory that there are a few problems with that statement. I learned while doing fieldwork that coring a tree does not damage it at all.
More importantly however, you can’t always find the exact age of a tree by simply counting the rings backwards.
Tree-ring series can be classified as either complacent (uniform ring widths where moisture and heat are sufficient throughout the growing season) or sensitive (pronounced year to year variation in ring width, where conditions are frequently near the limits of the trees tolerance, e.g. The search for proxy climatic data was the original application of tree rings. In 1901, he noticed ring-width variations on a cut log and reasoned that these were controlled by the tree's environment (Fritts, 1976).
Douglass (1920) illustrated the relationship between climate and ring width by plotting both against time, and introduced the technique of cross dating by correlating ring-width signatures (sequences of wide and narrow rings) among trees distributed over large areas.
Tree-ring dating provides scientists with three types of information: temporal, environmental, and behavioral.
The temporal aspect of tree-ring dating has the longest history and is the most commonly known—tree rings can be used to date archaeological sites, such as the Cliff Dwellings found at Mesa Verde National Park (MVNP) or historic cabins.
The dating process consists of comparing the sequence of tree ring widths in the sample to a dated master sequence.As soil water declines through the summer, the cells become thicker-walled and more dense.Thus each annual ring consists of early (light) and late (dark) wood. Douglass, the 'father' of dendrochronology was interested in the affect of sunspots on the earths climate.Sometimes a ring is there, but it’s tiny; so small you need a microscope to see it: a micro ring. I sit down to cross date my first batch of samples, black oaks from 2003, with rings I can see without using a microscope.I use the microscope regardless, of course, because sometimes what looks like a ring from far away can actually be a false ring: an “extra” late wood growth caused by an early freeze, early warming, or some disruption to ‘normal’ seasonal weather.