One summer day in 1872, photographer Eadweard Muybridge arrived at a cove on the west side of Lake Tenaya, the blue jewel halfway between Yosemite Valley and Tuolumne Meadows. The photograph he took there, like many of the 51 he took in the region that season, reflected his taste for intricate texture and moody atmosphere.

Sixty-five years later, in 1937, the great modernist photographer Edward Weston paused at the same cove. Standing two feet from where his Victorian predecessor had, he focused his camera straight across the water to make a pure, stark image. Five years after Weston, Ansel Adams stood about 20 feet farther south and used an even more powerful lens to capture a majestic picture of clouds and glacial domes.

My collaborators, photographers Mark Klett and Byron Wolfe, figured this out via triangulation and other calculations when we arrived at the lakeshore in 2002 with the earlier photographs in hand. They used rephotography — the exacting art of taking a photograph in the same place at the same time of day and year — to establish all this and then fit the old and new images together into a magnificent panorama of four moments in time, four visions of a place, in one continuous sweep. The horizon line is unbroken throughout the images, but the visions are dissonant: Muybridge embraced a chaotic foreground, Adams and Weston looked for distant sublimity, and my collaborators brought color into the mix.

You can't step in the same river twice, but you can learn a lot by heading back to the river to study why it's no longer the same. Over the course of three summers, Klett, Wolfe, and I explored Yosemite National Park with old photographs as our guides. Returning to the sites of images taken up to 140 years earlier, we were able to measure their changes with the eerie precision rephotography provides. We found that the great vistas of the 19th century were often wildly overgrown or entirely gone, because meadows had, for lack of fire, become forests.

We discovered that the Merced River in western Yosemite Valley had moved dozens of feet from where its bed had been when Muybridge photographed it. But time did not pass at a predictable rate in all places and through all processes. If time was a river, it had rapids, eddies, and backwaters. Some places were drastically altered, some astonishingly stable. A scene of glacial polish and boulders Muybridge photographed in 1872 had even the small rocks in the same places 13 decades later. Some trees changed beyond recognition or vanished.

The famous Jeffrey pine atop Sentinel Dome — photographed by both Muybridge and Adams — died in the 1970s and stood on, a skeleton, until it collapsed a few weeks after we visited it. But 65 years after Weston photographed a gnarled, majestic juniper at Lake Tenaya, it appeared utterly unchanged.

John Muir (who camped at Lake Tenaya three years before Muybridge got there) called the Sierra Nevada "the range of light." We saw it as a theater of time, which this project investigated in its many versions. These included changes not only in photography, but also in the way the place is imagined and managed. The Park Service and tourism have mutated repeatedly in the past century and a half. Victorian visitors took particular pleasure in the ancientness of the sequoias and the glacial traces on view in the valley walls and the peaks.

Geology was the definitive science of that Darwin-haunted era, while ours muses over invasive species, extinctions, development, and changing climate, and thus looks at wildlife, skies, and open spaces with some of the intensity with which past visitors regarded traces of the Ice Age. We expected to find great changes over a century but were sometimes surprised by what we didn't find. For example, though there is plenty of development in Yosemite (too much, by some lights), none of the old photographs we worked with showed sites that are now marred by hotels or parking lots. In one case, a hotel in the high country in 1872 had vanished without a trace.

We experienced another kind of change at Lake Tenaya. For me, it was the place where, in 1851, the Mariposa Battalion captured some of the region's indigenous inhabitants, told them they would never live there again (about which they were wrong), and replaced the Native name for the lake — Pyweak, or Shining Rocks — with the name of the leader of the captured band, Tenaya. When we came to rephotograph the cove, we met a widower scattering his wife's ashes at the site of their honeymoon campout some 40 years earlier. Human history has, happily, left few visible traces in many parts of Yosemite, but it is there all the same. Rephotography allowed us to measure the distance between the visions of earlier visitors and our own.

Rebecca Solnit writes further on rephotography in Yosemite in Time: Ice Ages, Ghost Rivers, Tree Clocks, to be published by Trinity University Press this August.