Radiocarbon dating worked example

We find places on the North Rim where volcanoes erupted after the Canyon was formed, sending lavas cascading over the walls and down into the Canyon.

Obviously, these eruptions took place very recently, after the Canyon’s layers were deposited ().

No geologist was present when the rocks were formed to see their contents, and no geologist was present to measure how fast the radioactive “clock” has been running through the millions of years that supposedly passed after the rock was formed.

No geologists were present when most rocks formed, so they cannot test whether the original rocks already contained daughter isotopes alongside their parent radioisotopes.

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.

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Part 1 (in the previous issue) explained how scientists observe unstable atoms changing into stable atoms in the present.The rate of uranium decay must have been at least 250,000 times faster than today’s measured rate! As this article has illustrated, rocks may have inherited parent and daughter isotopes from their sources, or they may have been contaminated when they moved through other rocks to their current locations.Or inflowing water may have mixed isotopes into the rocks.This source already had both rubidium and strontium.To make matters even worse for the claimed reliability of these radiometric dating methods, these same basalts that flowed from the top of the Canyon yield a samarium-neodymium age of about 916 million years,5 and a uranium-lead age of about 2.6 billion years!

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