A desert that depends on water
MOSCA – This may be the only desert in the world that depends on water.At Great Sand Dunes National Park and Preserve, sand caught in the prevailing southwestern winds of the San Luis Valley sweeps into a corner of the 14,000-foot Sangre de Cristo Mountains and gathers like dust bunnies under a couch.Then, streams rushing down from the mountains wash the leading edge of the sand back down into the valley to be whipped up by the winds again.The results are stunning.The sand piles in dunes, wave upon wave, 750 feet above the sagebrush deck, suddenly dives into Sand Creek and Medano Creek and ends.One side of the creek looks like a desert beach, the other is scrub oak, juniper and ponderosa pine forest.”My goodness. You could easily get lost out here just beyond the first dune,” said Robert Greenwood, a visitor from Lexington, Ky.”Yah,” said his wife, Johanna, who is German, as they walked out into the dunes.”I would find one of those flowing sheik hats very practical here,” he said.
“Yah,” she said.”It’s amazing. It’s as if someone has transplanted a piece of the Sahara,” he said.”Oh, yah,” she said.Although the sand looks like it’s transplanted, it’s actually closely tied to the surrounding landscape not just the creeks, but the shape of the mountain range, the trees on its sides, even the water that’s miles away and deep underground.Most visitors don’t stay long enough to see this. The average stay is less than four hours, and it took the Park Service more than 50 years to make the connection.”The sand is just a small part of a larger cycle. If anything changed, the dunes would change,” said Carol Sperling, the park’s chief of interpretation and visitor services. “We really didn’t realize that until the early 1990s.”It took another decade for the dunes’ advocates to push for an expansion of the park to protect the vital pieces of the equation.In 2004, the federal government finalized purchase of the 97,000-acre Baca Ranch, tripling the size of the Sand Dunes monument, making it a national park, and including all the parts of the system that create the highest dunes in North America.”It was the first time park boundaries were drawn up on natural boundaries, not political ones,” said Sperling.
Sand Dunes National Monument was created in 1932 to protect the dunes from prospectors who wanted to mine them for gold. At the time, the boundaries basically made a tight lasso around the 30-square-mile dune field.That seemed like enough. After all, the dunes don’t seem to change. An 1874 picture of the dunes by William Henry Jackson hanging in the visitor center looks just like the view from the center’s window today. Wind blows the sand slightly east in the morning and shifts it back in the evening.The Utes called this place Sowapohe-uvehe “the land that moves back and forth.”In the 1980s, plans to pump ground water out of the surrounding aquifer to ship to cities on the Front Range got people thinking about how a dropping water table would affect the dunes.”We started to realize how vital water is,” Sperling said. “The creeks move tons and tons of sand everyday.”If the water table drops because aquifers miles away are being sucked down, then the creek sinks into the sand before it can recycle the dunes.The creeks act like sheep dogs, keeping the dunes in a tight flock. Without them, the sand could spread out in a massive sheet that would eventually be covered by grass and trees.On the east side of Medano (Spanish for sand) Creek, “escape dunes” that jumped the creek during a dry cycle a few decades ago are moving toward the mountains 35 feet per year.”We realized if we didn’t protect our water, we might lose this amazing resource,” said Sperling. “We really had to protect the whole watershed to ensure the dunes would continue their cycle.”
The realization has been a boon to visitors, who now have miles more hiking opportunities in the park.A trip to the top of the dunes (something visitors have been doing at least since Zebulon Pike walked through) is a must. It’s a hike unlike any other in the region and rewards with a breathtaking view that sweeps from the salty playa ponds in the valley bottom to the stone spires of neighboring Fourteeners.But people who think they’ve already “done the dunes” should check out the Sand Ramp Trail. The 22-mile trail skirts the backside of the dunes. It offers great views of the sand sea and unexpected delights: hidden creeks disappearing into the dunes, elk tracks, and a phenomenal old-growth ponderosa forest where 300-year-old pines stand anchored in the sand.Most striking, hikers can see the connection among sand and wind and mountains up close.Individual grains of grit fly through the air. Fingers of dunes sneak up into canyons shaded by Douglas fir. Streams of melted snow sweep them back down again in an annual spring cleaning.Hikers with a careful eye who scan the grassy dunes between forest and sand might even glimpse the clumsy flight of the Great Sand Dunes tiger beetle, a specially adapted predator that lives nowhere else on Earth.It half-hops, half-flies, preying on mountain and prairie bugs that stray into the sand. Here is the whole dunes ecosystem in an animal the size of a sunflower seed.The beetle needs the forest next to the dunes to bring in prey. It needs the water from the creek to create a supply of sand for the dunes, and the winds from the mountain to keep them clear of brush.Just as with the dunes themselves, the beetle stakes its survival on the stark contrasts of prairie and sand and mountains, and the deep connection among them all.
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