Scientists can use certain types of fossils referred to as index fossils to assist in relative dating via correlation.Index fossils are fossils that are known to only occur within a very specific age range.
But, how can we determine how old a rock formation is, if it hasn’t previously been dated?Carbon-14, the radioactive isotope of carbon used in carbon dating has a half-life of 5730 years, so it decays too fast.It can only be used to date fossils younger than about 75,000 years.Unlike absolute dating, relative dating does not assign specific years to individual events.Instead, it seeks to establish which actions occurred where in a sequence of geologic events.The same rock formation also contains a type of trilobite that was known to live 415 to 425 million years ago.
Since the rock formation contains both types of fossils the ago of the rock formation must be in the overlapping date range of 415 to 420 million years.
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.
By studying relative dating, you prepare yourself to make your own insights about different kinds of ancient environments and biomes on the APES exam.
Relative dating is the process of establishing a sequence of historical events and relative ages of rocks by looking at sedimentary rock formations and their features.
Relative dating is an important topic in AP Environmental Science.