Cross dating for dendrochronology
The long and varied relationship of LTRR with 14C initiatives has continued with LTRR contributions to high-resolution studies through the 1990s and systematic efforts now underway that may eventually extend the bristlecone pine chronology back beyond its beginning 8836 yr ago as of 2009.
Dendrochronology or tree-ring dating, is the scientific method of dating based on the analysis of patterns of tree rings, also known as growth rings.
So in the absence of geochronology, two cultural groups can only be proved contemporary by the discovery of links between them.
If in culture A an object produced by culture B is found, A must be contemporary with, or later than, B.
However, its use is still helpful where recognizable products of dateable manufacture are found in undated contexts with no possibility of using a technique.
Dendrochronology can date the time at which tree rings were formed, in many types of wood, to the exact calendar year.