The American West embraces more than its share of spectacular landscapes. But there’s nothing else quite like the vast swath of canyons, mesas, sandstone spires and arches that stretches some 80 miles from north to south in the southeast corner of Utah, ranging in altitude from sagebrush flats to pinyon-and-juniper forests and old growth stands of ponderosa pine and Douglas fir.

This is the wilderness of 1.35 million acres that President Barack Obama set aside in 2016 as the Bears Ears National Monument. One year later, cozying up to the oil-and-gas lobby and the right-wing crusade to turn federal lands over to “the people,” President Donald Trump eviscerated the monument, cutting it in size by 85 percent. During the past three years, the Bears Ears has hovered in judicial limbo, after Native American groups and environmental activists filed lawsuits claiming that Mr. Trump’s reduction exceeded his authority.

That wilderness is my favorite place on earth. I’ve written four books about the Bears Ears region, and until last year, when the pandemic stranded me in my Massachusetts home, I had made pilgrimages there every year for 28 years.

The Bears Ears wilderness set aside by Mr. Obama is virtually uninhabited today, although a handful of small towns cling to its eastern and southern edges. This includes the thoroughly Mormon towns of Blanding and Monticello and the thoroughly counterculture Bluff.

Almost none of those sites has been excavated or restored by modern professional archaeologists or cordoned off for tourists to admire. I’ve spent some of the most enraptured days of my life hiking far from the nearest road to come unexpectedly upon dwellings tucked into hidden alcoves or petroglyphs etched into the dark patina of vertical walls, which few moderns have ever seen. Like my fellow devotees, I’ve taken home from those sites not even the tiniest potsherd as a souvenir, touched none of the fragile room walls so perfectly preserved you can still see the fingerprints of the builders grooved in the mortar. As a mountaineer, I’m dazzled by the climbing prowess of the ancients, and I’ve scared myself silly scrambling into high granaries and simply stared in awe at others I have no idea how to reach.

For decades, the Bears Ears was protected only by the light hand of Bureau of Land Management and Forest Service rangers. Fears of new oil and gas leases granted by federal officials after the downsizing did not come to pass. But the state of Utah did issue oil and gas leases on nearly 2,500 acres of state-owned land surrounded by the pre-Trump monument. And the century-old “hobby” of pothunters digging for black-market loot continued apace.

Into that vacuum, a horde of first-time campers, denied their usual vacations in Jamaica or the south of France, descended on the Bears Ears. They settled in with huge RVs and rode Jeeps, ATVs and trail bikes across the mesa tops, gouging new tracks and crushing the fragile cryptogamic soil. A Bureau of Land Management survey crew documented 25 miles of new “incursions” on Bears Ears land during the three-year hiatus — a significant portion of which was ruts blazed by tourist vehicles across land that had never before seen an impact heavier than the human footprint. This mob of recreationists left its ugly mark in human feces, new fire rings, and limbs hacked off living juniper and pinyon trees.

If the Bears Ears is my favorite place on earth, it has an even deeper significance for the members of what became the Inter-Tribal Coalition — Navajo, Ute Mountain Ute, Hopi, Uintah and Ouray Ute and Zuni — who started the push for the Bears Ears back in 2010, championing the first successful national monument spearheaded by Native Americans. Mark Maryboy, the 65-year-old Navajo activist who got the ball rolling, told me: “Most tribes feel that North America is still theirs, that it’s been stolen from them by the government, by white people. We still worship in those lands. The Bears Ears is our church, our cathedral.

Even as I plan my return to my favorite place on earth for the spring, I dread what I’ll find. But my personal loss is trivial compared with what anything short of complete restoration of the monument, and the oversight to keep it adequately protected from thoughtless desecration, will mean.

The original monument set aside by Mr. Obama comprises one of the most compelling landscapes in North America. But it’s more than that. With more pristine ancient dwellings, granaries and enigmatic galleries than any other wilderness in the United States, the Bears Ears constitutes an irreplaceable cultural treasure. We don’t have many of these places left to squander.

David Roberts is the author of “The Bears Ears: A Human History of America’s Most Endangered Wilderness,” published this week.