Radioactive decay and dating rocks
But for humans whose life span rarely reaches more than 100 years, how can we be so sure of that ancient date? Even the Greeks and Romans realized that layers of sediment in rock signified old age.
We note that at the instant the swimmer touches the end of the pool our wristwatch reads and 53 seconds.
How long has the competitor taken to swim the race?
When I have asked an audience this question they have looked at me incredulously and said, “Starting time?
Geologist Ralph Harvey and historian Mott Greene explain the principles of radiometric dating and its application in determining the age of Earth.
As the uranium in rocks decays, it emits subatomic particles and turns into lead at a constant rate.