Dating oaks
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There are a bunch of rather large oak trees in a park nearby to my
apartment, and I quite like to sit under them in the evenings on nice
days, to read or listen to the radio or just relax.  Ever since
reading "Wilding" by the aptly-named Isabella Tree last year,
which talks about "veteran oaks", I have wondered how old these
trees might be.

The other week I decided to stop simply wondering.  Knowing that you
can get a rough guess at age from the circumference of the trunk,
I brought a spool of yarn with me on an evening walk and wrapped
one around one of the trees, cutting it to length with my pocket
knife and bringing it home to measure.  It's surprisingly difficult
to keep the string perfectly parallel to the ground for the entire
way around, so any estimate obtained this way will probably be a
slight overestimate, but I did my best.  Back home I used a nice
old wooden metre ruler we found on the street to measure the string.
It was 4.64m.

Online I found a "Ready Reckoner" from the UK Woodland Trust to
estimate the age of an oak tree.  I'm not in the UK, and I don't
know how much variation there is growth rates between different
regions, but I figure this can't be too far off.  It takes the form
of a table with estimated ages for curiously spaced example girths,
with the spacing in the later part of the tree increasing by 2 feet
and one inch each line.  My oak falls 4.33m, roughly 232 years old,
and 4.98m, roughly 291 years old.  Linearly interpolating between
these two points yields an estimate of 260 years.  Of course this
method is only approximate, as was my measurement, but "older than
200 years" seems like a pretty safe thing to claim, and 250 years
doesn't feel outlandish.

This is not exactly old by the standards of oaks, which can
live to be over 500 years and in some cases even up to 1,000,
but it was older than I dared to hope when I decided to do this.
It's the easiest thing in the world not to give the age of trees
a second thought, but it's almost disorienting when you do.
This tree is about as old as the United States of America, it has
been growing since around the time of Cook's arrival to Australia,
it predates the industrialisation of most of the world.  It is
certainly substantially older than the technology of radio that I
often enjoy sitting under it.