Geologic dating techniques Old men fun chat
Scientists know that the layers they see in sedimentary rock were built up in a certain order, from bottom to top.
When they find a section of rock that has a lot of different strata, they can assume that the bottom-most layer is the oldest and the top-most layer is the youngest.
That means they don't really know how old their rocks actually are.
The key in relative dating is to find an ordered sequence.
Sort of an offshoot of stratigraphic succession is fossil succession, or a method in which scientists compare fossils in different rock strata to determine the relative ages of each.
In 1896, a French physicist named Henri Becquerel discovered radioactivity in an element called uranium.
He saw that it underwent radioactive decay, or emission of energetic particles to produce new elements.
Recently, he appeared on the evening news to talk about a new dinosaur he just discovered. Paul says he can tell from the fossils that superus awesomus lived on Earth about 175 million years ago.
Paul is super awesome, so I'm going to take him at his word.