In Norco, La., the loveliest, fluffiest clouds float in the sky, just waiting for children to see bunnies in them. They come out only during the day. That's because they come out of the Shell Oil refinery.

The town is named after the old New Orleans Refining Company. Shell bought the refinery, but the name stayed, and the locals still call the clouds "Norco cumulus." Kids who think they're looking up at simple water vapor are really seeing volatile hydrocarbons.

Photographer Richard Misrach tells this story in the caption of his 1998 image of a Norco cumulus cloud. In the photo, the refinery glints in the distance like an evil Emerald City, with one flame flaring from a tower.

Norco is one stop along a winding 150-mile stretch of the Mississippi River between Baton Rouge and New Orleans. The segment is part of the state's touted River Road, but nowadays folks just call it Cancer Alley. There are more than 100 industrial plants here, reportedly producing a quarter of the country's petrochemicals.

In a new exhibit at Stanford's Cantor Arts Center, Misrach's photos depict the river corridor's bayous, cypress trees and old plantations, together with its burping smokestacks, cracked concrete, heaps of trash and ragged chain-link fences. He couldn't capture the smells or the industrial noise, but they can be imagined under the misty-polluted skies. As can the myriad health concerns reported by residents, from rashes to cancer.

The photos were originally commissioned in 1998 by the High Museum of Art in Atlanta, as part of a "Picturing the South" series. Some but not all were exhibited and published, and more than a decade later the museum offered to display the show again.

Misrach decided that this was the time for new eyes and edits. The Berkeley photographer made plans to return to the South to shoot some updated pictures. He also enlisted a collaborator, New York landscape architect and Columbia University assistant professor Kate Orff, who studies ways to interpret and regenerate contaminated land. They went to Cancer Alley in 2010 to travel, photograph, study and interview residents.

The two have published a weighty book that goes with the exhibit. "Petrochemical America" contains large color plates of Misrach's photos, as well as Orff's maps, illustrations and graphs. In several instances she has overlaid Misrach's photos with her words and drawings. "Requiem for a Bayou," one of the overlays on display, shows how human mismanagement has turned "lush cypress trees into ghostly poles," as Orff wrote.

In her book, Orff also acknowledges that all of us are dependent on the petrochemicals that come from these industrial areas. "In multiple trips to New Orleans, driving up and down the River Road corridor to interview people, slathering up with sunscreen and bug spray, using chemical inks, printing multiple review drafts, and staring long hours at computer screens, it was impossible not to touch and, yes, be thankful for petrochemicals. One can project a future where many measured actions at the individual and community level that reduce exposure to everyday toxins and reduce waste, combined with aggressive federal public health regulations, would begin to change the trajectory curve of petrochemical use."

Most of the photos in the exhibit and book are from 1998; others come from Misrach's 2010 return visit. The newer photos don't appear to depict any improvement on Cancer Alley. In "Pipeline and River Road, Donaldsonville, Louisiana, 2010," for example, the sky is heavy with haze and a culvert runs with sickly green water.

Overall, the Cantor exhibit features 21 large-scale photos and 14 contact sheets by Misrach, as well as two Orff overlays. Entering the exhibit, a visitor is first faced with the big "Shopping Cart, Tanger Factory Outlet Center, I-10, Gonzales, Louisiana, 2010." One lonely cart stands in a vacant parking lot under dark skies.

Another striking photo depicts a small family home decorated with potted plants, in the very center of the picture. Then the viewer's eye is drawn up, along the height of the massive grain elevator right behind the house.

"Throughout Cancer Alley, homes, schools and playgrounds are situated yards from behemoth industrial complexes," Misrach wrote. "Residents within a one-mile radius of factories are subjected to significant air and water pollution as well as noxious odors and industrial noise. ... The quality of life in Louisiana has been rated one of the lowest in the nation. In contrast, extremely favorable taxation policies have helped draw industry to the region."

Many of the photos draw the eye in the way "Home and Grain Elevator" does: with a familiar image in the center such as a family home, cloud or cow. Then we pull back and see the larger picture.

"He tends to seduce your senses before your analytical brain realizes that something's wrong here," exhibit curator Elizabeth Kathleen Mitchell said last week at the show's opening.

Mitchell stood in front of a perfect example, a Misrach photo that places the viewer on a stone balcony at the Louisiana State Capitol in Baton Rouge. A telescope invites visitors to take in the panoramic views from the capitol — which turn out to be the smokestacks and clouds of an Exxon refinery.

Several images make reference to the South's haunting past. Along the River Road are many restored antebellum plantations, creating what Misrach calls another "surreal juxtaposition" with the industrial complexes. Amongst hazy landscapes are photos of the plantations' elegant columns, porches and furnishings. The mansions have become major tourist attractions. (In another contrast, one photo shows slave cabins in the woods.)

One plantation, Ashland Belle-Helene, stands behind chain-link fences marked "Shell Chemical." The white Classical Revival building, which is on property now owned by Shell, was built in the early 1800s and has stood mostly silent since the 1920s. Parts of the 1989 Chevy Chase movie "Fletch Lives" were filmed here, but during filming "the crew had to be evacuated when a fire broke out at a nearby toxic-waste dump," the exhibit book reads. "This Shell property is now closed to the public."

Even more quiet are the graveyards that still stand next to industrial complexes, even if their churches have been relocated. In the photo "Holy Rosary Cemetery and Dow Chemical Corporation (Union Carbide Complex), Taft, Louisiana, 1998," the graveyard has a background of rust and steel and a foreground of broken sidewalks. A few flowers have been left, but mostly the grave urns are empty. The sky is heavy and dark.

"That's almost too much," a man in the museum said, gazing up at the photo.

What: "Revisiting the South: Richard Misrach's Cancer Alley" and "Lee Friedlander: The Cray Photographs"

Where: Cantor Arts Center, Stanford University

When: The shows are up through June 16; gallery hours are Wednesday through Sunday from 11 a.m. to 5 p.m. and Thursdays until 8 p.m.

Cost: Free

Info: Richard Misrach and Kate Orff will give a free talk at Stanford on May 13 at 6 p.m. in Annenberg Auditorium. In addition, environment-themed films will be shown in the Cantor auditorium from 1 to 5 p.m. April 21 for Earth Day. The free event includes discussions and refreshments. For more about events and exhibits, go to museum.stanford.edu or call 650-723-4177.