Sunday, May 08, 2005


Rocks of Ages

As the Kansas science hearings progressed last week in Topeka, Science Coalition attorney Pedro Irigonegaray had an increasingly difficult time getting intelligent design witnesses to express an opinion about the age of the earth.

The way they hemmed and hawed, you'd have thought he was asking if Prof. Plum had done it in the library with a lead pipe -- or perhaps even worse, for them, if Prof. Plum had done it with Miss Scarlett in the study...

Is there really a scientific controversy about the age of the earth?

During a break in the hearings last week, Red State Rabble spoke with Kirsten Nicolaysen a Kansas State geologist whose area of expertise is the chemistry of volcanic rocks, including the methods for dating those rocks.

Nicolaysen explained that rocks are dated using multiple techniques.

The oldest rocks on earth -- some 3.96 billion years old, according to Nicolaysen -- come from along the Acasta River in Canada's Northwest Territory. In Australia, scientists have found a zircon crystal, a mineral, that is 4.3 billion years old.

How do they do it?

All rocks and minerals contain minute amounts of radioactive material. These radioactive elements are unstable, over time they spontaneously decay into more stable atoms. This decay occurs at a constant rate specific to each isotope -- isotopes are different forms of a single element that have the same number of protons but different numbers of neutrons in their nuclei. The rate of decay is usually described in terms of a half-life

Uranium 238, for example, has a half life of 4.5 billion years. It decays into a stable daughter product, lead 206. Uranium 235, with a half life of 708 million years, decays into lead 207. By looking at the ratio of parent to daughter isotope, geologist can determine the age of the rock. By looking at the ratio between both Uranium 238 and Uranium 235 and their respective daughter isotopes, geologists get a check on the date of the rock they are testing.

For intelligent design "theorists," it's not just evolution -- which they derisively call an historical science -- that challenges those among them who believe in a young earth. It's physics and chemistry.

Will we see a challenge to this part of the science curriculum next?


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