One of the most celebrated photographers in American history began his career by snapping the kind of family vacation pictures that betray no hint of visual genius. This should hearten any teenager whose early accomplishments with pen, camera, guitar or paintbrush seem inadequate to support dreams of artistic triumph.

Ansel Adams was 14 when he used a Kodak Brownie camera to take his first pictures of Yosemite National Park's luminous landscape. In the summer of 1916, when he and his family took that first trip from their San Francisco home to California's best-known national park, it required two days to drive across the Central Valley and penetrate the Nevada foothills.

It was a journey whose difficulty emphasized the separateness of that rugged place from the outside world. Once there, Adams fell in love, and the dramatic objects of his affection -- those soaring walls of granite, snow-draped crags, the interplay of light and shadow on water, rock and tree -- came to dominate his professional work.

In turn, his work would come to dominate America's imagination in a way that is difficult to appreciate today, when the images he produced have become so well-known, so imitated, so synonymous with the landscapes themselves, that we regard them almost as clichés.

We forget that there was a time when photographs of Yosemite and the other great Western parks were not ubiquitous, when there was still a large public waiting to be introduced to the labyrinthine depths of the Grand Canyon, the gravity-defying towers of Grand Teton, the implacable immensity of Denali in Alaska. And in forgetting this, we fail to appreciate the role such images have played over the past century in creating a broad public appreciation for landscapes as scenery, perhaps to the exclusion of their other values.

An opportunity to correct that amnesia and reflect on the mistakes in perception that flow from it may be found at the Los Angeles County Museum Of Art. Until May 11, the museum is hosting "Ansel Adams at 100," a traveling exhibition organized by the San Francisco Museum of Modern Art and now at its penultimate stop (it will move to New York this summer, having already visited San Francisco, Chicago, London and Berlin).

The exhibit encompasses the full range of Adams' professional work, from small, yellowing snapshots he took in the 1920s to document Sierra Club outings to the great, iconic images of his best years, the 1930s and 1940s. The accompanying catalog and audio commentary attempt, not altogether successfully, to trace Adams' evolution as an artist and infer meaning from his photographs of trees, mountains and lakes.

Many of Adams' most instantly recognizable photos are included: magnificent panoramas of Yosemite Valley from Tunnel View; a haunting moonrise over Hernandez, N.M.; a staggering shot of Mt. Williamson in the eastern Sierra Nevada from the boulder-strewn valley floor at Manzanar. There are gripping views of the Grand Canyon that can only conjure sad wistfulness, for the clarity and depth of field in those images from the 1940s has since been erased by a ubiquitous haze produced by smoke from a nearby power plant and smog blown in from as far away as Los Angeles.

The catalog discusses also Adams' role in the new conservation movement, which harnessed his photos of sublime beauty as justification for landscape preservation. It has been an effective tool, but also a perversely dangerous one, for it has helped foster the widespread sentiment that beauty is the meaningful criterion upon which to base a conservation strategy.

Interior Secretary Gale Norton demonstrated the ubiquity of that notion, and its unfortunate role as the guiding precept of Bush administration policies, when she tried to justify efforts to open the Arctic National Wildlife Refuge to oil drilling by deriding it in her recent Congressional testimony. She called the refuge flat, white nothingness.

Tremendous scenery deserves protection on aesthetic grounds alone, but there are qualities of the natural world worth valuing as well. Norton's department oversees hundreds of wildlife refuges -- which, like the wildlife refuge in Alaska -- exist to protect ecological relationships rather than pretty scenery -- and she ought to know this. But it’s a safe bet that she is not the only American to display this primitive level of regard for the landscape.

Ansel Adams helped a previous generation to appreciate the physical landscape of America. It is the task of the next generation to learn to value the things that Adams left out of his pictures.

John Krist is a contributor to Writers on the Range, a service of High Country News in Paonia, Colorado (hcn.org). He is a regular columnist for the Ventura Star in California..org). He writes in Kalispell, Montana.