Third, magnetism in rocks can be used to estimate the age of a fossil site.This method uses the orientation of the Earth's magnetic field, which has changed through time, to determine ages for fossils and rocks.A fossil can be studied to determine what kind of organism it represents, how the organism lived, and how it was preserved.
Layers of rock are deposited horizontally at the bottom of a lake (principle of original horizontality).
Younger layers are deposited on top of older layers (principle of superposition).
The age of the fossil must be determined so it can be compared to other fossil species from the same time period.
Understanding the ages of related fossil species helps scientists piece together the evolutionary history of a group of organisms.
Most sediment is either laid down horizontally in bodies of water like the oceans, or on land on the margins of streams and rivers.