What is the limitation of potassiumargon dating
Relative dating methods can not establish exactly how old things are, but only how old things are relative to other things.
Relative dating is based on the law of superposition which states that material found at the bottom of a sedimentary sequence is older than the material above it.
When volcanic rocks and minerals are formed, they do not contain fission tracks.
The number of tracks increases over time at a rate that depends on the uranium content.
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Instead, other methods are used to work out a fossil’s age.
Argon is gas that gradually builds up within rocks from the decay of radioactive potassium.Argon then starts to re-accumulate at a constant rate in the newly formed rock that is created after the eruption.This relatively new technique was developed in order to achieve more accurate dates than those obtained from the potassium-argon method.It is possible to calculate the age of a sample by measuring the uranium content and the density of the fission tracks.
The age of volcanic rocks and ash can be determined by measuring the proportions of argon (in the form of argon-40) and radioactive potassium within them.
It is initially formed in the molten rock that lies beneath the Earth’s crust.