Relative dating of fossils and rocks
This follows due to the fact that sedimentary rock is produced from the gradual accumulation of sediment on the surface.
Therefore newer sediment is continually deposited on top of previously deposited or older sediment.
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.
These include radiometric dating of volcanic layers above or below the fossils or by comparisons to similar rocks and fossils of known ages.
Knowing when a dinosaur or other animal lived is important because it helps us place them on the evolutionary family tree.
The Principle of Fossil Succession states that groups of fossils (called fossil assemblages) proceed one another in a regular and determinable manner.
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.
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.
Different methods have their own limitations, especially with regard to the age range they can measure and the substances they can date.
A common problem with any dating method is that a sample may be contaminated with older or younger material and give a false age.
This problem is now reduced by the careful collection of samples, rigorous crosschecking and the use of newer techniques that can date minute samples.
Search for relative dating of fossils and rocks:
Relative dating utilizes six fundamental principles to determine the relative age of a formation or event.