Potassium 40 dating problems dating japan for chinese

Part 2 explains how scientists run into problems when they make assumptions about what happened .

An hourglass is a helpful analogy to explain how geologists calculate the ages of rocks.

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Based on these observations and the known rate of radioactive decay, they estimate the time it has taken for the daughter isotope to accumulate in the rock.

However, unlike the hourglass whose accuracy can be tested by turning it upside down and comparing it to trustworthy clocks, the reliability of the radioactive “clock” is subject to three unprovable assumptions.

So geologists have assumed these radioactive decay rates have been constant for billions of years.

However, this is an enormous extrapolation of seven orders of magnitude back through immense spans of unobserved time without any concrete proof that such an extrapolation is credible.

Yet this view is based on a misunderstanding of how radiometric dating works.

Part 1 (in the previous issue) explained how scientists observe unstable atoms changing into stable atoms in the present.

This is the same age that we get for the basalt layers deep below the walls of the eastern Grand Canyon.4 How could both lavas—one at the top and one at the bottom of the Canyon—be the same age based on these parent and daughter isotopes?

One solution is that both the recent and early lava flows inherited the same rubidium-strontium chemistry—not age—from the same source, deep in the earth’s upper mantle.

These basalts yield ages of up to 1 million years based on the amounts of potassium and argon isotopes in the rocks.

But when we date the rocks using the rubidium and strontium isotopes, we get an age of 1.143 billion years.

Yet lava flows that have occurred in the present have been tested soon after they erupted, and they invariably contained much more argon-40 than expected.1 For example, when a sample of the lava in the Mt. Helens crater (that had been observed to form and cool in 1986) ( age yield incorrect old potassium-argon ages due to the extra argon-40 that they inherited from the erupting volcanoes, then ancient lava flows of unknown ages could likewise have inherited extra argon-40 and yield excessively old ages.

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