Geology Reference
In-Depth Information
The long half-lives of many of these methods allow geologists to date some of the most
ancient rocks on earth (and the moon!). How does a geologist know which method to
choose if he doesn't know the age of the rocks? First he must use relative dating and
stratigraphy to estimate how old the rocks are, and then he can choose the best radio-
active isotope system that is present in the minerals of his rock. Even so, using more
than one isotope pair measurement can provide the best result.
Exposing cosmic radiation
The age of rock and mineral formations is only one of the questions earth scientists have about past
geologic events. Many researchers want to know not only when the rock was formed but also when
