Scientists date igneous rock using elements that are slow to decay, such as uranium and potassium.
By dating these surrounding layers, they can figure out the youngest and oldest that the fossil might be; this is known as "bracketing" the age of the sedimentary layer in which the fossils occur.
He holds a Bachelor of Science, postgraduate diplomas in journalism and website design and is studying for an MBA.
Radiometric dating or radioactive dating is a technique used to date materials such as rocks or carbon, in which trace radioactive impurities were selectively incorporated when they were formed.
Geologists often need to know the age of material that they find.