Methods of dating rock layers
This relatively new technique was developed in order to achieve more accurate dates than those obtained from the potassium-argon method.The older method required two samples for dating and could produce imprecise dates if the argon was not fully extracted.
Measuring the proportions of argon-39 and argon-40 within a sample allows the age of the sample to be determined.
Knowing when a dinosaur or other animal lived is important because it helps us place them on the evolutionary family tree.
Accurate dates also allow us to create sequences of evolutionary change and work out when species appeared or became extinct. These are: Where possible, several different methods are used and each method is repeated to confirm the results obtained and improve accuracy.
Instead, other methods are used to work out a fossil’s age.
These include radiometric dating of volcanic layers above or below the fossils or by comparisons to similar rocks and fossils of known ages.The heat from a volcanic eruption releases all the argon from the molten rock and disperses it into the atmosphere.