Geologic Time is a crucial concept to understanding the history of the earth—including the evolution of life. Many different representations of the timeline have been created, and many approaches ...

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.

A Brief History of Life. By Lexi Krock; Posted 02.01.02; NOVA; It's hard to wrap your mind around the concept of 4.5 billion years. For many of us, the Pyramids–built 4,500 years ago, a ...