Fossil radioactive dating

The results showed that Ötzi died over 5000 years ago, sometime between 33 BC. Uranium has a very long half-life and so by measuring how much uranium is left in a rock its approximate age can be worked out.

Despite seeming like a relatively stable place, the Earth's surface has changed dramatically over the past 4.6 billion years.

This problem is now reduced by the careful collection of samples, rigorous crosschecking and the use of newer techniques that can date minute samples.

fossil radioactive dating-90

As these changes have occurred, organisms have evolved, and remnants of some have been preserved as fossils.

A fossil can be studied to determine what kind of organism it represents, how the organism lived, and how it was preserved.

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.

Sedimentary rocks are rarely useful for dating because they are made up of bits of older rocks.

Uranium is present in many different rocks and minerals, usually in the form of uranium-238.The second method is called absolute dating and is done by analysing the amount of radioactive decay in the minerals of the rocks.Scientists find out the age of a dinosaur fossil by dating not only the rocks in which it lies, but those below and above it.The carbon-14 it contained at the time of death decays over a long period of time.By measuring the amount of carbon-14 left in dead organic material the approximate time since it died can be worked out.Sometimes, scientists already know the age of the fossil because fossils of the same species have been found elsewhere and it has been possible to establish accurately from those when the dinosaur lived.

Tags: , ,