|Evolution in the News - June 2004|
|by Do-While Jones|
The “Time Lords” are revising the dates of the geologic column again.
Almost all of the dates on my 1994 Pan Terra geologic chart are wrong by a few million years. That’s because
… like fashions in hair or hem-length, the geological divisions of our planet’s timeline are prone to change. … The end of the Jurassic period, for instance, has wobbled by more than 30 million years since it was dated in the 1930s. 1
The International Union of Geological Sciences (IUGS) has now endorsed a new geologic column. Why?
To pin down the age of older rocks, geologists rely on radiometric dating, which tracks the radioactive decay of elements within a sample. But in the past decade, it has become clear that the results from different techniques and different labs don't agree.
The changing age of the Jurassic is a case in point. In 1987, the period was estimated to have ended 131 million years ago, based on the amount of potassium that had been converted into argon in a mineral called glauconite. But it was later discovered that argon seeps out of glauconite, making the mineral seem younger than it actually is. The new timescale used potassium-argon dating of basalt to put the end of the Jurassic at 145.5 million years ago.
"Most people will tell you that a measurement more than five years old is obsolete," says Gradstein. [Felix Gradstein of the University of Oslo, Norway, is the International Commission on Stratigraphy (ICS) chairman.] The inconsistencies highlighted by the timescale's construction prompted researchers to propose an international network of laboratories, all using a standard procedure, to which anyone could send a rock sample for dating. 2
What? Different techniques and different labs don’t agree? We are shocked! (Well, not really.) Not only is there an “excess argon” problem that we discussed in last month’s newsletter, there is also an “insufficient argon” problem. (We are ashamed to admit that we hadn’t heard of that problem before.)
Whenever we write about problems with radiometric dating, we get hate mail telling us that we are just looking a exceptional cases, and that radiometric dating generally agrees. The truth is that they don’t generally agree, and that it is very hard to get consistent results. That’s why this new timescale is so important to evolutionists. If they agree what the “right” answer is (based on the rock layer), they know which radiometric results to accept, and which to ignore.
Now geologists have an accurate, honest-to-goodness, rock-solid, geologic table. At least until 2008.
"We should have a second edition then,” he [Gradstein] says. 3
Until then, here is the official IUGS timescale.
International Union of Geological Sciences
|Beginning Date (millions of years ago)||Period||Era||Eon|
[Question marks in the original]
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Nature, Vol. 429, 13 May 2004, “Time Lords”, page 124
2 ibid. page 125
4 ibid. pages 124-125