Think of them as America's dinosaurs—trees so ancient, some date back to the birth of Christ; so immense, it can take ten people to encircle a trunk. Or as prototypical skyscrapers—the tallest living things on the planet. Or as nature's cathedral (wait until you see a shaft of light pierce the canopy and illuminate a single fern on the forest floor). They are also, tragically, teetering on the verge of extinction. And the chain saws are revving up again. Jim Robbins takes a walk through the woods

In the middle of a warm, sun-washed afternoon, I walked into a forest of giant redwood trees called Founders Grove in northern California, and into another world. The dense canopy all but blocked out the sun, and the velvety carpet of moss on the forest floor was bathed in a dark-emerald half-light. The air was delightfully moist and cool, probably ten degrees lower than in the sun. A fallen redwood lay on the ground like a beached whale. Even prone it was overwhelming—easily twice as tall as me—and played havoc with my sense of scale. I strained my neck in a vain attempt to see the treetops hundreds of feet above, and experienced a rush of timelessness—and of my own insignificance. I continued on through the cathedral-like silence and stopped at the base of a tree fifteen feet in diameter. A single shaft of butter-colored light pierced the canopy and fell in a pool beside the tree, illuminating a clump of sword-shaped ferns, like a sign from above; white moths flitted between the darkness and the light. "The clearest way to the universe," wrote the mystic and naturalist John Muir, "is through a forest wilderness."

Indeed, no experience on earth prepares us for a forest of giants. But a visit to America's forest primeval, while enchanting, is not what it once was. It is tinged with sadness, for the country's trees are but remnants of the great native forests, scraps left over after an orgy of cutting.

The loss is almost incalculable. When Europeans first made landfall here five hundred years ago, an unbroken blanket of forest stretched across much of North America, and a squirrel, it is said, could travel branch to branch from the Atlantic Ocean to the Mississippi, never once setting foot on the ground. But from the moment the first settlers walked off their ships, saws and axes in hand, the trees fell before them as they pushed west. Later the professionals—loggers and lumberjacks—took over to finish the job. The cutting has been relentless and, most of the time, thoughtless. More than ninety-five percent of the great pre-Columbian forests are gone, and the second- and third-generation forests that today cover most of America are shadows of what stood there before. Only isolated groves of old growth—mature, unlogged forests—remain, sometimes merely a single tree, mostly on public land; nearly all old growth on privately held acreage is gone.

Perhaps the most wondrous chunk of primordial forest left in the world is the coastal temperate rain forest along the Pacific, stretching from central California to southeast Alaska. It is by no means intact, but there is enough of it to inspire awe, and to suggest the forests that once existed.

Redwoods dominate at the southern, drier end of this corridor, which runs in a five- to twenty-five-mile-wide band from California's Big Sur up and across the Oregon border. They are the titans of old growth, taller even than the related (and more massive) sequoia, which occupy a much more limited range in eastern California. Some are more than two thousand years old. They grow like perpetual adolescents, adding two to six feet in height and an inch in girth each year. The tallest halt their upward arc below four hundred feet; beyond that, the trees' natural water pumping system can no longer defy gravity. The redwoods will continue to add to their diameter, however, growing to twenty feet across. As much as half of the moisture they need to survive comes from the drip of fog as it rolls in off the ocean and wraps them in its wet, life-giving embrace for days on end. Farther north, by virtue of heavier precipitation, the forest becomes a mix of Douglas fir and Sitka spruce, species that grow in less tightly packed clusters. These trees are big in their own right, but far smaller than the redwoods—just four or five feet around.