Radioactive dating organic materials
Potassium/Argon decay is used to measure ages of the “oldest” rocks.
The precise methods of decay vary, but the principle for determining age is generally the same.
Half-life is assumed to be constant and generally unaffected by heat, pressure, magnetic or electric fields, local chemistry or other environmental factors.
By measuring the amount of remaining helium in samples at specific depth intervals, and knowing temperature at each interval, known leak rate with temperature establishes the activity level and time.
Radiocarbon dating is one such type of radiometric dating.
A process for determining the age of an object by measuring the amount of a given radioactive material it contains.
The rate of decay is assumed to be relatively constant over time.
Once the decay rate is known, the time required to get from original ratio to present ratio is easy to calculate.