Radioactive dating method
Once we understand what we actually need to do we can apply the same principles to radioactive dating, and see if the methods do what they are claimed to do.
Picture a swimmer competing in a 1,500 metre race and an observer with an accurate wristwatch.
Radioactive elements were incorporated into the Earth when the Solar System formed.
All rocks and minerals contain tiny amounts of these radioactive elements.
As a result, rocks that record its earliest history have not been found and probably no longer exist.
A commonly used radiometric dating technique relies on the breakdown of potassium (Ar in an igneous rock can tell us the amount of time that has passed since the rock crystallized.
If an igneous or other rock is metamorphosed, its radiometric clock is reset, and potassium-argon measurements can be used to tell the number of years that has passed since metamorphism.
Radioactive elements are unstable; they breakdown spontaneously into more stable atoms over time, a process known as radioactive decay.
Radioactive decay occurs at a constant rate, specific to each radioactive isotope.