No. 3 Among the Dunes: White Sands National Monument
White Sands National Monument pays homage to some particularly mysterious work of Mother Nature – 275 square miles of white sand dunes that wax and wane at the whim of a passing breeze. The pure gypsum that forms these unusual dunes originates in the western portion of the monument from an ephemeral lake or playa with a very high mineral content. As the water evaporates (theoretically as much as 80″ per year!), the minerals are left behind to form gypsum deposits that eventually are wind-transported to form the dunes. Insider tip: bring a sled. You’ll thank us later.