Just when I thought...

Just when I thought I knew everything about... dendrochronology!

Reading more of Jared Diamond's book Collapse today as I walked to the market (to recycle some cans and bottles, of course), I was expecting my most interesting find of the day to be something about the stages between the North American south-west inhabitants' 11,000 year-old hunting-gathering lifestyle, and their pre-collapse, agriculture-based lifestyle in 1100 A.D.

Instead, I was left in awe, shaking my head in disbelief at just how simply ingenious dendrochronologists (Greek roots: dendron = tree + chronos = time) are with the methodologies they have developed for using tree rings to build very exact historical data.

Of course every school kid knows that counting the rings on trees tells you how old the tree is. School kids that even pay the slightest attention also know that thin rings mean years of drought, wider rings mean more growth, and scars from fire or what not can help indicate some climate related data from years past.

When I was a school kid though, I apparently was too busy wondering if I would get to sit next to Jessica the next time the desks were rearranged, to hear our teacher tell about how dendrochronologists can also use a combination of live trees, dead trees, and wooden beams used in construction of old buildings and what not to create tree ring records dating back for thousands of years.

Read on and be amazed at how simply ingenious it is. (for those who already know this - I feel sorry for your childhood which was obviously devoid of the perils of unrequited love).

So, lets say you have a big tree in your yard. It is estimated to be about three hundred years old. According to family lore, your great great great great great great grandmother once buried her beloved (dead, of course) parakeet at its foot. Now, the city has decided that they need to widen the road in front of your house in order to accommodate the expected increase in single-occupant SUV traffic headed to the new Big-Box store down the street. The tree will have to come down.

The future Big-Box site is an area which has, until now, been "just a forest" - inhabited only by animals n' stuff (what a complete waste of space!). It doesn't take long, however, before construction crews unearth the remains of an ancient structure, complete with stone tools, dishes, and human and animal bones. Following orders, the crew secretly relocate the remains to an illegal dumping site in the dark of night, lest those wussy "activists" find out and pressure the city into halting progress and economic growth in favor of a bunch of dead people whose culture was not even fit enough to survive into the year 2006.

A year after the big-box is built, all that remains of the tree that once marked your great great great great great great grandmother's pet parakeet's final resting place is your living room coffee table - a two-inch thick slice from the base of the trunk - now beautifully lacquered with lots of persistent toxic chemicals which bring out the "original luster". The parakeet's grave is now home to your TV/VCR/TIVO/DVD/Home Entertainment Center remote control, three empty beer cans, and a pizza-stained place mat.

Two years later a member of the original construction crew, now lying on his death bed with cancer caused by a lifetime of exposure to "show me the absolute proof that it is dangerous" asbestos, suddenly feels guilty about the way they hid what might have been an important archaeological find. He tells his son, who later tells one of his many dendrochronologist drinking buddies.

So what can the denrochrologists learn? (assuming they are not too drunk).

Well... this just made my day.

What they have:

• Well preserved wood from an ancient ceremonial hall of unknown age - but presumed to be the oldest evidence of civilization in the area discovered to date.
• Knowledge that there are probably other structures buried in the area. - After a long battle, well publicized bribing of government officials by Big-Box and, most importantly, revelations that a friend of the daughter of the Big-Box general-manager's cousin is... *gulp* GAY!, public sentiment finally tilts (just enough) against Big-Box allowing archaeologists to dig under the parking lot. (Until now, the public was vehemently against excavating the parking lot because it would mean they have to walk further to get from their car to the store.)
• A 2 inch slab of a newly cut tree believed to be several hundred years old.
• Pieces (in the museum) from houses built by the earliest European settlers - unfortunately, those settlers were an illiterate bunch, and there are no records of exactly when they arrived.

How can they tell how old the buried structures are? Based on my limited understanding):

1. Check out the rings on the coffee table, carefully ignoring any rings that could have been prevented with a coaster. Let's say there are 400 rings, indicating of course, that the tree is actually 400 years old. This means that the tree felled in 2000 (to make the math easy) was "born" in 1600.
2. Look for patterns in the rings that indicate drought years and wet years. It may be something like "7 thin, 3 thick, 5 thin, 1 fire-scared, 1 thin, 3 thick", a pattern which occurred when the tree was, say, 50 years old (1650).
3. Look in the rings in the beams of the old City Hall. They look for the same "7-3-5-1-1-3" pattern in the wood. Let's say that pattern occurs 50 years (1650) before the tree was cut. This tree also happens to be exactly 400 years old.
5. Count back from that 1650 pattern. Once they find the pattern, which occurred 350 years after that particular tree was "born", they now have ring records dating back 750 years.
6. Look for patterns in wood from the Big-Box excavation site that match 700 year old rings in the Town Hall beams. And the process continues for even older and older beams found under the parking lot.

image taken without permission from The Ancient Bristlecone Pine

Eventually, those god-like dendrochronologists not only have tree ring records dating back thousands of years, providing insights into past civilizations and climate patterns in the region, but they will also have sobered up now that they finally have something to keep them busy and out of the bars.

As for you and your coffee table, the city is "persuaded" to claim the rest of your yard, your house, everything in it, and your children under "eminent domain" - in order to build a new "Ancient American Fun Land" amusement park (your children are required to play the role of "naked native kids").

Now, I'm sure that even this simple attempt of mine to share what I only learned about today is full of errors. If so, please don't contact me or tell me. I like to revel in my own false genius.

Jeez I have too much time on my hands!