Mark Klett at Etherton Feb. 19

A young mining engineer named Raphael Pumpelly ventured into the Arizona wilderness back in 1860.

"Above us the sky was clear, but over the mountains we had left all was dark and gloomy," he later wrote.

"As the thunder rolled in peal after peal, and lightning broke in great columns, its sudden light impressing on the eye the weird rock-forms and frowning cliffs of the Arizona mountains, it seemed ... as though that region were ... in reality the 'Gate of Hell.'"

Pumpelly had found himself in the dreaded El Camino del Diablo.

Danger has always lurked along the Devil's Highway. Originally an Indian footpath, the route snakes through the driest, hottest, remotest desert in Arizona, running from Ajo to Yuma close to the border. Spanish soldiers and missionaries faltered in its heat centuries ago, and would-be 49ers heading to California in search for gold died of thirst out there.

More than 130 years after Pumpelly undertook his journey, photographer Mark Klett came across his book. Klett, a celebrated photographer and a professor at ASU, has always had a historical bent; he's best known for his "Rephotographic Project," for which he made new photos of western sites that had been shot in the 19th century by the expedition photographers. He decided to follow Pumpelly into the outback.

A dozen of Klett's color "Camino del Diablo" photos from his most recent trips in 2013 and 2014 are on view at Etherton Gallery, in "Mark Klett: Then + Now."

"Faint trail, granitic mountains near Raven Butte," 2013, could be an illustration for Pompelly's dire warnings of the trail's dangers. A pale moon hangs over forbidding peaks, and the mountains' rocky slopes seem ready to block off the trail, offering no exit for the hapless traveler. In "Rattlesnake Attempting to Flee," the rattler almost disappears in the white-hot heat and light.

Murderers and bandits haunted the trail in Pumpelly's day; today it's traveled by smugglers hauling drugs and human cargo up from Mexico. Like the 49ers before them, migrants too often perish in the blazing heat; Luis Urrea's "The Devil's Highway" recounts the tragic deaths of 14 border crossers on a single day in 2001.

Klett records the activity of the Border Patrol agents who roam the territory. He photographed one of their helicopters in "Hovering over smugglers," the chopper framed by the black circle of Klett's binoculars. In another ominous shot, he captured the agents working by night in the darkness, using the lights from their SUVs to illuminate the footprints of border crossers. Aiming his camera toward Mexico, he photographed a swathe of border wall, and its hostile web covers the entire surface of the print.

The Border Patrol is not the only

military presence. Today's camino is part of the Barry M. Goldwater Bombing Range, and Klett made a close-up of an unexploded shell dropped from a military plane and lying on the parched ground. The shells littering the ground are so potentially dangerous that visitors are warned not to touch them.

One of the photos captures both the beauty and danger of the Devil's Highway, both the "wonderfully clear atmosphere, with a bright sun and an azure sky" admired by Pumpelly and the "history of violence and surveillance along the border" described by Klett.

At first the picture looks like a simple landscape: a blooming ocotillo blooms beneath a flawless blue sky, on a lit-up desert ground. But a closer inspection reveals a military installation almost invisible behind the green arms of the ocotillo. It's a fake mosque, made out of shipping containers, that's used to train Marines for combat in a different desert terrain.

But a few shots favor just the camino's ravishing beauties. "Sunrise near Raven Butte, Gila Mountains," 2014, records the bluest of skies above, and below an amber cliff tinted in the bright yellow of dawn.

The exhibition also includes work from two other Klett series, "Revealing Territory" and "Time Studies."