Example Application of Crossdating

After crossdating, dendrochronologists can: Assign the true year of formation for every ring of each sample Analyze past environmental and/or human events. For example, see image to right:

© J.D. 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.
© 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.
© H.D. Grissino-Mayer	Dendroarcheological sample: Chronology from archeological samples: Wooden beams, uprights, and other structural parts 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