The activity below allows you to build a tree-ring chronology.
Each horizontal bar represents the tree-ring pattern for one tree. By looking
for matches in the patterns, you should be able to build an overlapping
sequence that stretches back in time. You can move the chronology to the right
and left using the arrows. Afterwards, go on to the next feature (see below).
The technique used here to create a chronology of tree-ring patterns is similar
to the one that dendrochronologists use. Called crossdating, the process
has established tree-ring chronologies for many areas around the world.
Some of these chronologies extend back thousands of years. In the American
Southwest, using both living and dead samples from the long-lived bristlecone pine (the oldest one
has been growing for a remarkable 4,600 years), scientists have constructed a
continuous history of tree rings that stretches back almost 9,000 years, to
about the year 6700 B.C.
Note: This activity is meant simply to illustrate the principles involved in
creating a tree-ring chronology. In creating actual chronologies,
dendrochronologists make use of skeleton plots, which are graphical
representations of tree-ring patterns.