Geologic Time

 Fossil is any trace, imprint or remains of living things preserved in Earth's crust.

Fossil is formed when living things where covered , or buried by mud or sand soon after they died.

Eras is a long streches in Earth's history. We live in the Cenozoic Era in the Quaternary period.

 

Superposition is the idea of rocks layers that the one that is in the bottom is the oldest and the one that is in the top is the youngest. Using this idea, scientist try to determine the relative age. Also it exist the geologic column a list of Earth´s rocks.