Example Application of Crossdating

After crossdating:

The true year of formation can be assigned for every ring of each sample
Past environmental and/or human events can be analyzed
Overlap in time can be found, as shown at right:

Photo provided by J.H. Speer	Living tree sample: Chronology from living trees: Photo: Ponderosa pine in Oregon Known bark date (e.g., the present year) is starting point After crossdating samples from living trees, dendrochronology extends back in time, e.g., AD 1500.
Photo provided by H.D. Grissino-Mayer	Dead wood sample: Chronology from dead trees: Standing snags or fallen logs, like this ponderosa pine remnant in New Mexico Lived for a long time and died long ago If dead trees lived concurrently with the living tree chronology: Outer growth of dead trees crossdates with inner portions of living trees Dendrochronology extended further back in time, e.g., AD 1200.
Photo provided by H.D. Grissino-Mayer	Dendroarcheological sample: Chronology from archeological samples: Wooden beams and uprights of ruins like the Tonto Ruin, Arizona If archeological samples lived concurrently with the dead wood chronology: Outer growth of structural samples crossdates with inner portions of dead trees Dendrochronology extended further back in time, e.g., AD 800 Past human behavior reconstructed and analyzed

Good Idea: When you try skeleton plotting, think of how to apply the dates of ring formation

Paul R. Sheppard
Laboratory of Tree-Ring Research, The University of Arizona
Tucson, Arizona 85721 USA
office: (520) 621-6474, fax: (520) 621-8229
Comments to: sheppard@ltrr.arizona.edu