Absolute dating technique volcanic rock

10 Apr

To determine the relative age of different rocks, geologists start with the assumption that unless something has happened, in a sequence of sedimentary rock layers, the newer rock layers will be on top of older ones. This rule is common sense, but it serves as a powerful reference point.Geologists draw on it and other basic principles ( to determine the relative ages of rocks or features such as faults.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.Absolute dating is used to determine a precise age of a fossil by using radiometric dating to measure the decay of isotopes, either within the fossil or more often the rocks associated with it.The majority of the time fossils are dated using relative dating techniques.This problem is now reduced by the careful collection of samples, rigorous crosschecking and the use of newer techniques that can date minute samples.

Say for example that a volcanic dike, or a fault, cuts across several sedimentary layers, or maybe through another volcanic rock type.

If a geologist claims to be 45 years old, that is an absolute age.

Superposition: The most basic concept used in relative dating is the law of superposition.

Absolute dating places events or rocks at a specific time.

If a geologist claims to be younger than his or her co-worker, that is a relative age.