Dendrochronology

Some unidentified tree ringsDendrochronology is, of course, the method of using tree rings to date things. Our records go back as far as 11,000 years in some cases, which is incredibly useful for archaeological purposes and as a side effect also demonstrates that such dates existed to boot – you can see how that might worry young Earth creationists. For his October Acts & Facts article John D. Morris wants to talk about Tree Ring Dating and its problems.

Several species of trees live almost indefinitely. The giant sequoia trees of California are known to live over 3,000 years, discerned through tree ring dating. Under normal circumstances, woody trees add one ring per year. A ring typically consists of a light-colored growth portion and a dark-colored portion produced in a stabilization season. However, some trees do not produce annual rings at all, especially those in temperate or tropical regions.

Actually, it is those that are in temperate regions that produce the best rings, as the seasonal changes in growth are the clearest. Morris needs to show us that dating via this method is unreliable. You’ll note the lack of specifics on his part.

But how valid is the assumption of one ring per year in a climate where tree-growing conditions are variable? That very assumption is regularly put to the test by research foresters. They investigate how a tree grows, how and when it adds a new ring, effect of nutrients, rainfall, etc., over a range of related conditions.

He cites this to a DVD from Creation Ministries International, called Tree Rings, Dating and Changing Climates. He provides no other references to help us check his claims, and he may well have got all of his information from that video.

It has been found that all trees, even slow-growing ones, respond dynamically to tiny environmental changes, even hourly changes in growing conditions. Scientists have observed that numerous “normal” conditions can produce an extra ring or no ring at all. Weather was fingered as the most “guilty” culprit. Unusual storms with abundant rainfall interspersed with dry periods can produce multiple rings, essentially one per major storm. Thus, the basic assumption of tree ring dating is demonstrably in error. Can we trust the overlapping calibration curves?

Temperature anomalies in the "year without a summer"The question that needs to be answered (and is not) before we can make any judgement here is which type of tree is being examined. Some trees are more useful than others – oak, for example, is supposed to have missed a ring only in the Year Without a Summer (1816). ‘False’ rings exist in some cases, but these can be found so that they can be ignored in counting. And if the ring production was as fickle as Morris claims then why is there such consistency, both internally and with carbon dating and cases where dates are known from historical sources?

As it pertains to Flood model considerations, remember that the centuries immediately following the Flood witnessed the coming of the Ice Age. All trees growing on the continents were recently sprouted, actively growing trees. The still-warm oceans rapidly evaporated seawater, thus providing the raw material for major monsoonal-type storms. Earth was ravaged by frequent and wide-ranging atmospheric disturbances, dumping excessive snowfall in northern regions and rainfall to the south. If ever there was a time when multiple rings could develop in trees, this was it. Those centuries probably produced tree ring growth that was anything but annual.Thus, far from disproving biblical history, tree ring studies provide supportive and instructive information about true history.

Increasingly I’m finding that a post-flood ice age is simply assumed by creationists. There are problems with this idea, and I should probably take some time at a later date to go over it. If this period is supposed to be responsible for a disruption to the normal production of tree rings, can it be simply assumed that it would result in a net increase, and of several thousand? Something that would be interesting to check would be how many rings each ancient tree has – do they suddenly have thousands each after some point, as they grow a lot more than one a year? I doubt it. If what Morris is saying is true he should really be able to give clear evidence beyond that the rate of ring production can vary. There should be some positive evidence, but all he has is a reference to a random DVD by another creationist organisation. Hardly the most trustworthy source, in my opinion.

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One thought on “Dendrochronology

  1. You can always tell when it’s a science-denying YEC who is discussing science. They start putting words in quote marks for no obvious reason eg ‘chronologies’ or ‘dates’ or they keep using words like ‘supposedly’ or ‘alleged’ or ‘claimed’. A bit of a give-way.

    Though when they are spouting their evidence-free YEC scenarios – as in the final paragraph here – all scientific caution miraculously vanishes! Of course they are deciding that something unverifiable – but in ‘accordance’ with Bible timescales – definitely happened. And then fitting the evidence from tree rings – including any cases where more than two were produced in a calendar year – into that unverifiable (and extra-blblical) scenario. After all, the Bible talks of 40 days of rainfall – and NOT unusually warm oceans or “frequent and wide-ranging atmospheric disturbances dumping excessive snowfall in northern regions and rainfall to the south” after the flood of Noah. THAT is a YEC invention – designed to fit observable science eg large icecaps and u-shaped valleys gouged out by ice with scripture.

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