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.
To date a radioactive rock, geologists first measure the “sand grains” in the top glass bowl (the parent radioisotope, such as uranium-238 or potassium-40).
They also measure the sand grains in the bottom bowl (the daughter isotope, such as lead-206 or argon-40, respectively).
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?
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.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 ().PART 1: Back to Basics PART 2: Problems with the Assumptions PART 3: Making Sense of the Patterns This three-part series will help you properly understand radiometric dating, the assumptions that lead to inaccurate dates, and the clues about what really happened in the past.Most people think that radioactive dating has proven the earth is billions of years old.
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.