1. Intro to Tree-Ring Dating Jan 12, 2009

2. Crossdating

3. Crossdating

4. Crossdating • Crossdating is the procedure of matching and synchronizing ring-width patterns among trees that have grown in nearby areas, allowing the identification of the exact year in which the ring was formed. • Dated and measured rings from a number of trees in a region are combined to form a tree-ring chronology.

5. Crossdating • A tree-ring chronology must have at least 50 trees or wood samples from the same genus. • This will decrease the influence of noise. • The chronology can be used as a tool for dating events that caused tree death or a marked change in the appearance of a ring or set of rings.

6. Anomalies in Ring Growth • Missing ring – a ring that is entirely absent from a tree • Locally absent ring – a ring that is not present throughout the entire circumference of the tree

7. Anomalies in Ring Growth • False ring – when it appears that more than one ring has been created in 1 growing season

8. Skeleton Plots • Skeleton plot is a graphical representation of ring width patterns, used in crossdating. • http://tree.ltrr.arizona.edu/skeletonplot/SkeletonPlot19.htm