Prehistoric time line, geologic time scale, photos, facts, maps, and more from National Geographic. Humans have walked the Earth for 190,000 years, a mere blip in Earth's 4.5-billion-year history.

An Index fossil is any animal or plant preserved in the rock record of the Earth that is characteristic of a particular span of geologic time or environment. We will look at a few index fossils and ...

Smith’s map and ideas paved the way for a better understanding of geological time and laid the founding principles for geological surveys worldwide. His concept of using fossils to identify rocks is ...

A moderately strong, 5.2-magnitude earthquake struck in Southern California on Monday, according to the United States ...