[Transcript]
Journey into the Dunes
Off we go, into the dunes! There's about four and a half billion tons of sand out here, and the dunes can reach 60 feet high, or about as tall as a five-story building. Now, from here on out, the road is going to be made of packed sand. While a little bumpy at first, I think you'll find that it's surprisingly smooth.
Origins of White Sand
Okay, do you remember all that geology I told you about back on the highway? So, let's continue the story and learn how all this white sand ended up here. But first, a little recap. So, around three million years ago, the Rio Grande flowed along the Tularosa Basin and blocked the outlet to the sea with sediment, creating the ancient Lake Otero.
All the water flowing from the surrounding mountains into the basin was trapped down here. Do you remember what mineral appears in those mountains? That's right, gypsum! This was from way back when this area was under the sea. So, the water from the mountains carried dissolved gypsum into the lake, and that gypsum settled on the lake bed.
Now, the lake hung around for a couple of million years, but around 11,000 years ago, the climate got warmer and Lake Otero evaporated. The gypsum, though, was still here. Without water, the gypsum formed into crystals.
Years and years of freezing and thawing broke the crystals into pieces of all shapes and sizes, and winds racing across the basin whipped the delicate crystals into tiny particles of sand. It also pushed the sand around, forming this giant field of sand dunes. And that, my friends, is what surrounds us right now.
Evolution of a Landscape
The process continues today. Occasional heavy rainfall creates a small, temporary lake in the place of Lake Otero. And when the lake dries up, the crystals form, and the action starts all over again.
But why is the sand white? Well, the grains of gypsum sand get all scratched up as they bang into each other. The scratches then reflect the sun, making them appear white. These dunes are less than 11,000 years old, well within the time humans have lived here, and they continue to grow and move as the winds of time leave their mark, shifting as much as 30 feet a year.
It makes you wonder, what will this place look like in another 11,000 years?
