AGE OF RED OAK TREES

[WINDLINE]

Find either a dead red oak or a live one which can be cut, nearby, the
larger the better.  Count the rings (drying and staining makes it easyer)
along any radius, and divide the radius in inches by the ring count.  Now 
divide your 54 in. tree by two to get the radius:27 inches. Divide 27 by
the average ring size obtained from the smaller dead or sacrificed tree.
The ring size will vary by species and local yearly weather variation, but
as long as the sample tree size is at least 10 or 15 years old, the
averages will also hold for the older tree. the accuracy is probably 95 %
and can be incrteased by averaging more trees for the average ring
thickness.

Robert Barbour