Dating fossils through strata and radiometric samples
Sedimentary rocks are rarely useful for dating because they are made up of bits of older rocks.
In fact, the very concept of strata representing long ages does not come from the rock strata themselves.
This is different to relative dating, which only puts geological events in time Most absolute dates for rocks are obtained with radiometric methods.
These use radioactive minerals in rocks as geological clocks.
The resulting rock strata may harbor fossils from a particular habitat area or ecosystem, but do not represent a particular age or era.
Why else do we find marine fossils on the tops of all the major mountain ranges?