By RICH GRANT

SAN LUIS VALLEY, Colorado – The young Spanish priest felt his wound where the arrow had gone in, and realized he was dying. His comrades fired a few more shots at the fleeing Indians, then laid the priest down on a patch of sand facing the mountains to the east. The peaks were blood red with the reflection of the setting sun.

“Sangre de Cristo!” the priest whispered, then died. “Blood of Christ!”

And so, in the early 1600s, legend tells us, the Sangre de Cristo Mountain Range of southern Colorado was named.

It is a beautiful range. From a distance, the evergreen-covered slopes appear to be blue. Rocky crags, 13,000 and 14,000 feet high, hold snow year-round and turn colors with the setting sun. But it is at the base of this range that the most spectacular and unusual sight can be found. The soft, curving and dramatic wind-sculptured sand dunes of the San Luis Valley.

They are the highest inland sand dunes in North America, rising to more than 750 feet. Pink, cream, brown, tan or gold – depending on the angle of the sun – they are shifting mountains of sand. Each day, the winds go to work on them. A strong wind can set the whole dune surface moving, creating ripples, building the sand into elegantly shaped crescents or adding onto the loose masses called climbing dunes. But sooner or later, reverse winds blow down from the mountains and the dunes are returned to near their original shape. Photos taken in 1927 show that the main dunes have undergone very little change in the past 80 years. Except that in 1932, they became a National monument and in 2004, roughly 50 square miles of this ocean of sand and another 70 square miles of surrounding mountain land became the Great Sand Dunes National Park and Preserve.

There are many activities in the park, but everyone’s first choice is hiking in the dunes. There are no trails in here – they wouldn’t last an afternoon – so visitors can go anywhere they want. But first, to get to the dunes, you have to cross shallow Medano Creek, which flows between the dunes and the Visitor Center. It’s best to just take off your shoes and wade across the soft, water-cooled sand creek, but be sure to wear shoes into the dunes. In mid-summer, the sand can reach 140-degrees F.

On the other side of the creek, the dunes are incredibly massive, and due to shadows, deceptively steep. The pure physics of the sand says that it can’t be piled at an angle steeper than 34 degrees. Seventy percent of the grains of sand are .2 to .3 millimeters in diameter – the width of a human hair. Stacked any steeper than 34 degrees, and they simply give way to gravity and cascade down. But because of shadows, you’ll swear differently – especially as every step you take up, you slide back down halfway. Not to mention, the dunes are at 7,500 feet above sea level, making breathing hard in the best of conditions.

But the effort of climbing the dunes is worth it. It is like riding the frozen waves of a storm-blown sea. You climb to the top of a ridge, taking in a view of the gold and tan waves stretching for miles to the towering blue mountains, then descend the trough until you are in a valley completely surrounded by immense hills of the sand. The highest dune in North America, Star Dune, is located opposite the Visitors Center and takes about six hours to hike to and return. Or maybe more. On a recent hike, we climbed the wrong ridge, only to discover too late that we had to descend more height than we had gained just to get to the base of the highest dune. It was like starting over after two hours of hiking. Most people can easily make it to the top of the first ridge and back in a few hours, and the sight from this spot gives you more than enough view.

It’s hard not to wonder up there, where did all this sand come from? What are the some of the world’s highest sand dunes doing in the middle of Colorado, 7,500 feet above sea level?

The easy answer is, they were blown here. The great San Luis Valley is the highest alpine valley in the world – an area the size of Massachusetts with the San Juan Mountain Range to the west and the Sangre de Cristo range to the east. It’s a dry place, with only 11 inches of precipitation a year and little vegetation. It’s also one of America’s most deserted places. Only 40,000 people live here. This isolation makes it one of the quietest and darkest places on the planet at night. Small wonder that there have been more UFO sightings in the San Luis Valley than even in nearby Roswell, New Mexico.

For hundreds of centuries, an almost incessant wind has come down from the San Juan Mountains to the west and blown over the valley, picking up small grains of sand from dry river beds, ancient dried up lakes and the valley floor, and carrying them toward the towering wall of the Sangre de Cristos. Only three passes of low elevation break this chain of peaks, and the wind sweeps through these natural funnels. At the base of these passes, there is a trap – a pocket that because of turbulence and friction allows wind and dust to pass, but not the heavy grains of sand carried by the wind. Caught in this natural trap, the sand has slowly accumulated. Scientists think the sand dunes are less than 440,000 years old, but they really don’t know. Changes in climate, vegetation and rainfall could impact the dunes, at any time.

Since the three passes behind the dunes were the easiest way of getting over the mountains, most of the West’s early explorers passed this way. Zebulon Pike, after whom Pikes Peak is named, and Kit Carson came this way, as did tribes of Utes, Apaches, Comanches and Cheyennes.

And who knows? The dunes – or at least the darkness, lack of light pollution and the quiet they bring to the area – may have attracted UFOs. Local resident Judy Messoline thought so. She built the world’s only UFO Watchtower near the park’s entrance. It’s really just a wood deck, but it’s as good a place to look for UFOs as any, and a small museum details the history of the strange number of astral sightings and cattle mutilations that have taken place in the area, some dating back to the 1700s. Judy claims that 88 UFOs have been sighted from the tower since it went up in 2000. Of course, her autobiography is titled, “The Crazy Lady Down the Road.”

Also just down the road is Crestone, a small town of 150 people at the base of the mountains that is very much like walking into an episode of the “X-Files.” Crestone has more ashrams, stupas, Catholic retreats and spiritual centers per capita than any place in the world. There are 30 of them here, scattered in the mountains. Many locals believe that Crestone holds an energy vortex and is perhaps a portal to other dimensions. You can learn about this, and the artists who live in the area, at the Crestone Historical Museum and Welcome Center. It’s well worth driving 9 miles off the main highway to see this little artist community and its colorful ashrams.

IF YOU GO

People have been trying for decades to slide down the dunes on snow skies, on homemade cardboard sleds and aboard flying saucers made for snow. Unfortunately, they don’t work. But there are specially designed sandboards and sand sleds that do work and are available outside the park at the Oasis store. You can’t really “fall off” an edge in the dunes (no matter how steep it looks, you’ll just slide down). However, the dunes can be dangerous. Blowing sand can be fatal to cameras, and can sting exposed skin and eyes. And, of course, it’s a terrible place to be in a lightning storm, so hikers should always observe caution and avoid being on the dunes in storms.

The park has camping, ranger programs and miles of hikes into the Sangre de Cristo Mountains including a spectacular hike to Zapata Falls. The nearest town is Alamosa, Colorado, which has a variety of local and chain motels, a great brewpub and some very good Mexican restaurants.