Absolute dating geology
Absolute dating is expensive and takes time while relative dating is less-expensive and efficient.
Absolute dating is the technique that determines the exact age of a historical remaining while relative dating gives the order of age of several samples.
Here is an example of how valuable index fossil are when trying to relatively date some rock strata.
If you come across a Paradoxides pisus when looking at rocks, you can be assured that the layer in which you found this fossil is from the Cambrian Period or about 500 million years old, because the Paradoxides pisus lived 500 million years ago and it has never been found in any other rock strata that is either younger or older.
They can show how some species lived and what specie replaced them.The main difference between absolute and relative dating is that the absolute dating is a technique to determine the numerical age of a rock or a fossil whereas the relative dating is a technique that determines the relative age.Furthermore, absolute dating can be done with the use of radiometric dating while relative age is determined with respect to other layers.It is a less advanced technique when compared to absolute dating.Some methods used in relative dating are stratigraphy, biostratigraphy, and cross dating.
Cross-cutting relationships states that any feature that cuts across a body of rock is younger than the rock that it cuts across.