"Every large strip mine could support an artist in residence. Flattened mountain tops await the aesthetic touch ... Bottomless industrial pits yawn for creative filling -- or deepening."

Though Morris' concerns lined up with those of the mainstream environmental movement -- he even spoke about climate change in the aforementioned speech -- his approach did not. The generally accepted way to clean up a mine is to try to return it to its "natural" state in the hope that observers, if not the landscape itself, will forget that it was ever disturbed. Turning strip mines and waste dumps into art, on the other hand, monumentalizes, perhaps even consecrates, the harm they inflict upon nature.

Spiral Jetty is not reclamation art, but it is a direct engagement with the industrialized landscape of the Great Salt Lake. It's about a three-hour drive from Bingham Canyon, past Salt Lake City and clusters of housing developments, what Smithson referred to as "slurbs." Robert Adams -- another artist of the Anthropocene -- photographed Denver's slurbs in the 1970s in all their stark and soulless beauty.

Turning away from the slurbs toward the Lake, one encounters the great paradox of places like this: The further you get from "humanity" and into "emptiness," the more likely you are to encounter the types of human intervention that we'd rather not witness on a daily basis. Among farm fields, still muddy from winter, sits a giant Walmart distribution center, rows of tractor trailers getting loaded with goods. We pass bucolic bovines grazing golden grassy hills and see signs on a low fence warning of grievous danger. The Thiokol Promontory Complex, now owned by ATK, tests its rockets here, in reportedly spectacular events that scorch entire hillsides. Farther up the road, the rocket facility itself sits in the middle of "nowhere," with a surreal-looking "rocket garden" out front.

Beyond that is the Golden Spike National Historic Site, where the Union Pacific and Central Pacific branches of the Transcontinental Railroad were joined in May 1869. It's yet another reminder that this landscape has been prodded and poked and bulldozed and grazed and even blown up for decades, maybe millennia. In the theory of the Anthropocene, no one is really sure when the epoch begins. Was it when humans started fire to manage game, when they first cultivated crops or at the dawn of the industrial age? Whatever the starting point was, we are now deep into it.

"The lesson here," says Philip Ursprung, the leader of the Swiss expedition, as we stare at the rockets, "is that there are no neutral landscapes." Or natural landscapes, for that matter, the distinction between trammeled and untrammeled having been wiped away long ago.

As many as 40 people a day visit Spiral Jetty. Given the proliferation of academic papers, blog posts and even a sort of Eat, Pray, Love of land-art tourism known as Spiral Jetta -- it seems that more people are writing not just about the art, but about the journey they make to see it. Perhaps that's because the trip is part of the artwork; Smithson's own account of searching for and then discovering the site is more than context, it is an actual extension of the Jetty.

The travel accounts, often narrated by non-Western urbanites unaccustomed to this sort of emptiness, not to mention washboard roads, tend to become a bit effusive. Philosopher of art Stephanie Ross called the work of Smithson and Heizer "masculine gestures in the environment" because of their scale and because "traveling to see them requires braving wilderness, rattlesnakes and the desert's climatic extremes" -- the worst being automobile air-conditioning. One blogger spends several sentences earnestly describing cattle guards and warning readers not to trespass on ranches "if you are at all fond of your current good state of health and approximate proper count and localization of body parts."

Mysterious cattle guards and murderous ranchers aside, the final stretches of the gravel road to Spiral Jetty are smooth and easily traveled in mid-March. At road's end, we see the same reddish water that so inspired Smithson and experience the same "crushing light" he did. Like Smithson, we see detritus from earlier oil drilling, though the old truck and amphibious vehicle that fascinated the artist have since been hauled away. And, just like Smithson, we see the big empty place where Spiral Jetty is supposed to be. We don't, however, see Spiral Jetty.

Just a year after Smithson completed his colossal sculpture, it was inundated by the rising lake. It reappeared in 1993 and re-entered the art world's collective consciousness more forcefully than when it was first built. Then it disappeared, and then re-emerged. Today, it's completely submerged, invisible except for the white foam piled up where it connects to the land. A couple of the people I'm with, determined to experience it, wade out into the water, getting their shoes wet and foamy and salty.

The rest of us listen to Bob Phillips, the foreman of the crew who drove the dump trucks and earthmovers that actually constructed the Jetty more than four decades ago. Phillips remembers everything and relishes recounting his own journey from dumbfounded skeptic to full-on Smithson convert. "He (Smithson) wore very dark clothes, dark horn-rimmed glasses, black hair that kept getting in his eyes. He was completely different than me. I was blond, short crewcut. I was prepared to tell him, ‘I can't do that.' " Smithson showed Phillips pictures of his work, including his Asphalt Rundown in Rome and a box filled with rocks. He told him of his plans to turn the Bingham Pit and the empty spaces around various airport runways into art. While that didn't inspire Phillips, Smithson's intensity and intellect did.

"He kind of convinced me he was on the up and up," says Phillips, "though I couldn't possibly see how he could make a living doing that."

Phillips described the site as "a really crummy-looking place," what with the abandoned vehicles, scattered oil barrels and an actual oil seep oozing into the water. But after a lot of rocks and dirt had been moved, "It was just a beautiful piece of art."

SUN TUNNELS

“As in nature itself, everything connects with everything else.” -Lucy Lippard, activist and writer known for her work on contemporary art (and neighbor of Holt’s in Galisteo, N.M.), in an essay about Holt.

Nancy Holt once said that it was the "dialectic between human-made elements and raw nature that drove her creative process and introduced an exhilarating tension into the work." That tension is palpable in the first leg of the drive between Salt Lake City and Holt's most famous work, Sun Tunnels, which sits near the Utah-Nevada border. Here there is a wilderness of sorts, mostly void of humanity but irrevocably trammeled. You name it, it's happened: salt mining, hazardous waste incinerators, a chemical weapons dump, even bombing ranges on both sides of Interstate 80.

With a Swiss student and an artist as my passengers, I turn north at Wendover, where the Los Angeles-based Center for Land Use Interpretation -- which is devoted to the "exhilarating tension" Holt spoke of -- has its major field station. We venture onto an empty washboard road across the flats, driving way too quickly in hopes of smoothing out the bumps. (It doesn't work.) A series of straight lines, not unlike the Bingham Pit's benches, etch the slopes of the mountains that rise up from the plain. They mark the drop, over thousands of years, of the ancient Lake Bonneville, which once covered this whole expanse. We encounter a flock of sheep, but their big white canine minders chase us away. Finally, we find what we're looking for, a jumble of what looks like culverts out on the flats.

Holt began work on Sun Tunnels in 1975, on 40 acres that she bought the year before. It consists of four 22-ton concrete tunnels arranged in a big X, in what at first appears to be an utterly random location and configuration. It is both sculpture and observatory: Each tunnel has holes drilled into it that line up with the constellations, and each pair of tunnels respectively aligns with sunrise and sunset on the summer and winter solstices. The work is a descendant of the ancestral Puebloan solstice markers in Hovenweep and on Fajada Butte in Chaco Canyon (both of which mark the sunrise with spirals), as well as the more sophisticated observatory at southwestern Colorado's Chimney Rock, which pinpoints the moon's maximum declination every 18 years. There are plenty of other ancient precedents, from Stonehenge in England to the Southwest's Chacoan "roads."

Your first impulse at Spiral Jetty is to seek out a higher vantage point in the landscape in order to better see the work. At Sun Tunnels, you want to climb inside the sculpture and peer through its holes from the inside, in order to better see the surrounding landscape -- exactly as Holt intended.

"I wanted to bring the vast space of the desert back to human scale," wrote Holt in 1977. "The panoramic view of the landscape is too overwhelming to take in without visual reference points." It's like a super-sized version of Holt's earlier "locater" works, one of which she built near Missoula, Mont., in 1972 -- metal poles topped with tubes through which one could look and "locate" something on the landscape.

There are no somber museum guards here, snipping at us for standing too close to the art. A Cézanne or a Caravaggio can be comprehended from a reasonable distance, even from a good print or photo of the work. Land art demands that the viewer physically interact with it, even clambering on or through the sculpture. The old subject-object relationship that exists with more traditional art is demolished, and the boundary between the artwork and its surroundings is also lost. The empty space between Double Negative's two trenches is as much a part of the sculpture as the trenches themselves, as are the field, the sky and the lightning at Walter De Maria's Lightning Field. When oil companies considered drilling within view of Spiral Jetty and then Sun Tunnels, art lovers worldwide rose up in protest: Drilling nearby was essentially the same as drilling the artwork itself. After all, who can say where Spiral Jetty begins and ends?

In this way, successful land art serves as a bridge between human beings and the landscape. At its best, it repeats and shares the experience Holt had when she first ventured West, and realized that "inside and outside were the same. I was the land and sky and the land and sky was me."