When geologic incidents disturb the strata or upturn them to a vertical position, the principle of paleontologic identity, in which two layers containing the same fossils are from the same period, is used.Absolute dating (or radiometry), based on the principle of disintegration of certain radioactive elements, establishes the age of fossils.Below, an ammonite dies and drops to the bottom of the body of water (1).
The largest of these units, eons, are divided into eras, then into periods (or systems) and epochs.
Thus, for example, it can be calculated that an organism has been dead 22,920 years when only 1/16 of C14 remains in relation to the C12.
This technique is currently used to date vestiges less than 50,000 years old.
The trade-off is that the second method gives us a more precise answer to the question of “how old is this rock? Can you place these cars is relative order from oldest to youngest?
When you think you know the answer, click on the image to see if you are right.