White Sands, an area located in New Mexico’s Chihuahuan Desert, is famous for its rolling white dunes. Last year, this natural wonder became the 62nd national park in the U.S.

The dunes at White Sands National Park are made of the mineral gypsum. Tens of thousands of years ago, a lake covered the area. Its waters contained dissolved gypsum washed down from nearby mountains. Over time, the lake dried up. Wind eroded the thick layer of gypsum left behind into sand-size grains, which piled into dunes.

The dunes span an area nearly as big as New York City. The sight of them is otherworldly, says park ranger Kelly Carroll.