In this case, the use of fossils will be absolutely the best method available.Second, it is much faster than any more technical method.
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.
This problem is now reduced by the careful collection of samples, rigorous crosschecking and the use of newer techniques that can date minute samples.
Volcanic rocks – such as tuff and basalt – can be used in dating because they are formed at a particular moment in time, during an eruption.
For really old dates we need to use radioactive isotopes.
RADIOACTIVE ISOTOPES ARE UNSTABLE VERSIONS OF NORMAL ELEMENTS.
Rather than employ the services of such a laboratory, it is so much cheaper for the geologist to recognize a well-known species of ammonite, trilobite, foraminiferan, or whatever, the age of which is already known.
The first method of finding the absolute age of an object is by examining tree rings.If our stratigraphic methods show that fossil A was always deposited below fossil B whenever we are in a position to compare their dates of deposition, then we can conclude that species A is older than species B.We can apply the same sort of reasoning to the stratigraphic relationships of fossils and datable rocks.If there wasa very long winter then there will be a thinner tree ring.Another method of determining absolute age is by looking at varves.Later in the year, by wintertime, the clay has had enough time to settle to the bottom and it forms a thin layer of dark colored rock.