I’m a national park nut. I’m especially fond of the large-landscape parks in the Western United States. I love to visit them to ogle the panoramas, see wildlife, learn about their histories and ecosystems, and explore their backcountries. Last October, my husband, Jack, and I planned a trip to South Fork, Colorado, to cast for trout in the Upper Rio Grande River. When I spotted Great Sand Dunes National Park and Preserve nearby on the map, I put it on our “must-see” list for the trip. Then life got busy. No time to plan beyond the list, but I figured I could at least hike up a sand dune for some exercise prior to a long day in the car on our way back to Denver airport. Preparing for a sandblasting never occurred to me.

Beach Without Water

As we traveled across the flat plain toward the visitor center at the park, I peered at the dunefield to our left from the shelter of our rental car. The base of the dunes resembled a luscious beach without water. In fact, some people walked along the strand without shoes on, digging their toes into the pliable, pale grains.

Beyond, the dunes rose layer after barren layer in mesmerizing patterns. They grew like thousand-foot waves rolling toward Mount Herard, a prominent 13,000-footer in the Sangre de Cristo range at the far end of the goliath dunefield, which blocked their northeastward flow.

Prevailing winds continually pushed sediments from San Juan Mountains, 65 miles away to the southeast, toward the Sangre de Cristo Mountains, that framed the dunefield. Around 400,000 years ago, a lake covered the valley between the two ranges. As the lake evaporated, the prevailing southwesterly winds picked up and bounced sediments and pebbles against the Sangre de Cristo’s. Then storms blew them back toward the plain, piling them on themselves and creating the tallest dunes in North America.