Later that evening, we speak about the 40 years of travel and monastic penny-pinching that have made Kelsey's lifestyle possible: buying used clothes at thrift stores, subsisting mostly on rice and vegetables, driving 45 mph on desert highways in un-air conditioned vehicles to save gas, working out of the basement of his parents' home in Provo, and -- most of all -- carefully avoiding marriage. "I'm married to this," he says, sweeping a hand across a vertical panorama of sandstone walls.

He describes his childhood in the Uinta Basin. Kelsey's father lived well into his 90s and scratched out a living as an itinerant lumberjack and gilsonite miner. The family moved to Provo in the mid-'50s, and Kelsey has remained there ever since. He severed his ties with the Mormon Church at the age of 17 after a class discussion about the lack of divine intervention during the group's expulsion from Missouri, the prophesied Garden of Eden. "I walked over to the seminary the next day and turned in my card. They call that apostasy," he says. "I guess that makes me an apostate." Kelsey says he sees religion as a great destabilizing force worldwide and plans to write a book on what he sees as the United States' troubled relationship with Israel. (I tell him that if he thinks his critics are vocal now, he's seen nothing yet. "I'll write that when I can't walk anymore," he replies.)

He's got enough writing projects to keep him busy for now. He's got books "laying around," he says in a rare moment of ennui, older editions that need to be updated, including his first published guide, the Climber's and Hiker's Guide to the World's Mountains and Volcanos (a 1,200-plus page tome covering hundreds of peaks from the Tetons to the Hindu Kush) and his more local Hiking Guide to the San Rafael Swell. "The San Rafael guide needs to be revamped and re-photographed," he says with a hint of despair. "Maybe in the next year or two if I can get to it."

After a few final preparations, we set out for the trailhead. Kelsey moves nimbly down the steep, loose terrain. The trail offers a panorama of the aptly named White Canyon, cut into cream-colored sandstone. We pass another warning sign, a facsimile of the one posted at the trailhead -- also duly ignored -- and work our way to the bottom. Kelsey maintains a swift but sub-Olympian clip, and in a half-hour we catch up with another group as they traverse a stretch strewn with massive boulders. Though currently water-free, the area is littered with logs, root snags, tires and heaps of garbage.

"This has changed!" Kelsey declaims, his voice echoing from the canyon walls. At each new obstacle he pulls a small pad from a Ziploc bag tucked into his back pocket. Those three words become a sort of mantra during our two days of hiking. Geologic time, we think, occurs over a period too vast and imperceptibly slow for human perception. And yet, along the canyon floor, a sharp eye can spot the water-wrought changes from season to season. ("Seeing a flash flood catches God red-handed," Colorado author and flood-chaser Craig Childs once wrote.) Indeed, these beautiful and ephemeral places defy description in even the most thorough of guidebooks.

No place is the mantra more disconcerting, however, than the spot where White Canyon contracts into the cave-like fissure of the Black Hole itself. "This is where we go in, but, man, this has changed. Last time I was here, I jumped over to that other side," he says, pointing to a seven- or eight-foot gap. On the other side is a steep slab of sandstone. A jump looks like a risky proposition. Fortunately, a bit more scouting reveals a tight crack that drops us into a dark, water-filled pocket.

The next defile is even narrower and the scant light that penetrates diffuses off the undulating walls. A fraying length of rope hangs into the void with knots down its length. Kelsey drops into the pool first, levering awkwardly away from the rock face. I do the same, swinging out then penduluming back, steadying my body against the rock with my feet.

Then I let go.