Just three years ago, a group of Idaho men traveled to an unnamed Western state and in an unnamed range of rugged mountains, hiked up a steep trail. At the top, they unraveled climbing ropes, stepped ...

Deep below the Earth's surface, rock and mineral formations lay hidden with a secret brilliance. Under a black light, the chemicals fossilized within shine in brilliant hues of pink, blue and green.

Through the intricate study of lava tubes -- caves formed following volcanic eruptions when lava cools down -- an international team of researchers has uncovered clues about Earth's ancient ...

Through the intricate study of lava tubes—caves formed following volcanic eruptions when lava cools down—an international ...

Mammoth Cave, the world's longest known cave system, stretches 426 miles under Kentucky. The cave's limestone began forming 330 million years ago when the region was submerged under an ocean. Visitors ...

For years, scientists were mystified by the origins of Hells Canyon, the deepest river gorge in North America. This massive natural wonder is a staggering ten miles wide and plunging more than 2,400 ...

Beneath the surface of an otherwise unassuming National Park, a labyrinth showcases hundreds of millions of years of geologic history. Each shade of tan layered on the walls represents a different era ...