This photo was submitted to Your Shot, our photo community on Instagram. Follow us on Instagram at @natgeoyourshot or visit us at natgeo.com/yourshot for the latest ...

His photos appear frequently in National Geographic magazine ... It's a new world when you get up there. Textbook geology (dry as dust in the classroom) leaps to fascinating life.

National Geographic is running a challenge for users to submit photos that "celebrate the beauty of the planet" for Earth Day ...

His photos appear frequently in National Geographic magazine ... setting my own clock to the time frame of geology, blocking off the rest of the world, and entering into a sort of communion ...

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.