Prehistoric park filled with the fossils of dozens of extinct species including Australian megafauna.

Aqueducts have dramatically changed this old lake, now home to tufa towers and its very own species of tiny brine shrimp.

The cinder cone volcano with a less than complimentary name.

Most-visited and most-photographed slot canyon in the American Southwest.

Dramatic river bend surrounds a natural red-rocked pedestal.

Rippling sand dunes frozen in the Arizona rock.

Eons ago, a rushing lava river formed this pristine passage through solid rock.

The second-largest cave chamber in the world was discovered in 1898 by a 16-year-old and a friend known as "Pothead."

Trails through lava-carved tube-caves display sparkling bacteria and a rich history.

Explore the largest pure gypsum deposit in the world, and go dune sledding while you're at it.

This "dead marsh" sits among the largest sand dunes in the world, a forest frozen in time.

When ecosystems collide in the arid Southwest.

See massive fossils that are over 200 million years old in northeastern Arizona.

A seemingly endless landscape of pure salt stretches far across Bolivia.

A desert that rolls right up to the ocean, where it's so dry animals live off the fog.

Oregon's unexpected high desert, displaying layers of time in a colorful show.

Over the dunes of the Empty Quarter, the mysterious music of the desert.

Landscape of bizarrely shaped desert mountains and innumerable rock carvings.

The tallest stationary dunes on Earth also happen to sing.

Even King Tut was intrigued by the glass of the Great Sand Sea.