The granddaddy of them all

YELLOWSTONE NATIONAL PARK, Wyo.--One small body of water here goes by the name of Grand Prismatic Spring, and, in some ways, Grand Prismatic might serve to describe this park in its entirety.

At just 370 feet across, Grand Prismatic Spring is still the largest of Yellowstone's many hot springs and one of the most vividly beautiful sights in the park.

From deep-blue depths at the center, a rock-rainbow of underwater colors spreads, ranging from opalesque to greenish to orange and representing the hues of various algae that manage to grow within the cauldron. An overlay of steam -- reflecting the same colors -- blurs and softens the effect and renders this small segment of a huge park rather magical.

Grand Prismatic Spring is not the picture that usually comes to mind when the subject of Yellowstone National Park comes up. We tend to think of Old Faithful and its wedge-shaped plume of steam. Or we envision the mountains, the lakes that mirror them, the boiling sulphuric mud and steam vents, the variety of wildlife from bears to bison to wolves.

It is a grand prism of a park -- taking off in several directions like refracted light beams. The theme of it could well be Earth itself in all its diversity and turbulence.

Since the fires of 1988, some parts of Yellowstone also remind us that flames torched 790,000 acres, leaving dead lodgepole and whitebark pines -- gray, silver and black trunks clinging balefully to reviving hillsides.

Motorists on the main roads see little of that, and now hardly anyone would claim that the flames dealt Yellowstone a knockout punch.

Fires are part of the wilderness life cycle; they clear out the unhealthy detritus that chokes the forest floor. Vegetation comes back with renewed vigor. A couple of human generations may not see Yellowstone return to full pine-topped glory, but an abundance of glory remains.

Yellowstone probably became a national park so early in the nation's history because its unique properties were recognized early on. Several tribes hunted in the plateau that is the sunken cone, or caldera, of a huge volcano. Trappers spread the word (Frenchmen coming up with Riviere des Roche Jaune to describe the river lined with cliffs of yellow sandstone rocks).

After the big California gold strike in 1848, miners roamed the West looking for more. They turned up quite a bit in areas surrounding Yellowstone, and sent back word to the East about the fantastic lakes and geysers they found in northwest Wyoming, northeastern Idaho and southwest Montana.

Expeditions began exploring the "wonderland" in 1869 and 1870, coming back with credible reports of astounding scenery and a wilderness thick with wildlife. Dr. Ferdinand Hayden, director of the United States Geological and Geographical Survey, quickly launched four official expeditions with government funding.

Hayden's team of botanists, geologists and zoologists created several maps and reams of notes, but photographer William Jackson and artist Thomas Moran provided the visual proof that the "wonderland" did exist.

Heeding public clamor to preserve Yellowstone, in August, 1872, President Ulysses S. Grant signed a bill that made that section of the country a "public park and pleasuring ground for the benefit and enjoyment of the people."

Yellowstone thereby became the first national park in the world and one of the earliest indications that the U.S. public recognized how continuous hunting, trapping, mining and paving of the frontier eventually would destroy great natural assets. Those efforts are far from over, but Yellowstone's 125th birthday festivities begin in earnest next month.

(Pre-Yellowstone, the concept of setting aside wilderness as park land was not entirely new to Americans. In 1864, Congress gave to California the lands known as Yosemite with the understanding that the state would preserve them for public enjoyment. Eventually, California returned Yosemite, and in 1890, it was granted full status as a national park.)

On a map, the main highways of Yellowstone resemble a rough figure-eight with tentacles leading to the main points of the compass. The U.S. Army and pioneers of the tourism industry laid out the loops. Before the army took over the park in 1896, hunters and hide dealers slaughtered the wildlife, while heedless early tourists carved their initials into soft rock and algae beds, bathed in the hot springs, dug up vegetation and took home petrified wood.

Most early visitors (and many who arrive even today) failed to grasp the why of Yellowstone. It contains the largest concentration of geysers, mud pots, fumaroles and hot springs in the world, because hot, plastic blisters of magma here creep within a few miles of the Earth's surface.

Water seeps in through cracks in the surface, drops down, picks up tremendous heat and rises under great convective pressure through vents to the top.

Red-hot, liquid rock -- confined to the Earth's core in most of the world -- lurks beneath the highways and picnic tables of Yellowstone. It breathes through the steam vents and thermal pools, roils the mud pots and sends great showers of hot water out of the geysers.

A volcanic eruption 600,000 years ago created a caldera some 40 miles long and 30 miles wide in what is now central Yellowstone. The great explosion virtually emptied the closest magma layer, causing the surface to collapse thousands of feet into the magma pool below that. As recently as 60,000 years ago, lava flowed freely through cracks in the surface, leaving fluted cliffs pocked with frozen bubbles and petrified logs once encrusted with cooled lava until winds and rain eroded it.

"There are craters underneath us, where hot springs have flowed," Marsha Karle, a park interpreter, told me recently. She was sitting in a sunny office at park headquarters in Mammoth, near the north entrance. A few hundred yards away, visitors swarmed near hot springs that were shaping dramatic terraces out of scalded mud.

Karle said a work crew removing a gasoline storage tank recently came upon a huge cavity that no one had realized was there. Structures in the headquarters complex were built in the 19th Century with thick limestone walls. Unfortunately, builders didn't consider what might be happening below the foundations. "Who knows, we may just disappear into the earth one of these days," Karle said with complete aplomb.

And if human-built facilities don't start falling into craters, there is always the volcano to consider. I reminded Karle that Yellowstone has been billed as "dormant."

"Which means it could blow at any time," she said, laughing. "Some people come here not realizing it's a dormant volcano and that it's very big. If it decides to erupt, you'd have to go a long way to get away from it. They say it will erupt every 600,000 years, and it's been about that long since the last eruption, so it really could happen in the next 100,000 years or so."

University of Utah seismologists monitor earthquake activity in the park. Tremors occur constantly but people rarely feel any shaking. If they did, it might signal another eruption; more likely, it would simply serve as a reminder that this is one lively section of the western landscape.

One morning, signs at the Old Faithful visitor center announced that the next eruption of the famed geyser would occur on or around 11:25 with a 10-minute margin for error -- or, really, the imprecision of thermodynamics.

Beginning around 11:10, visitors strolled in from the parking lots, the general store, the visitor center and the Old Faithful Inn lobby. They wandered around the gurgling hole in the ground, or sat on benches. A few fiddled with camera tripods and light meters.

It was a large crowd -- several hundred -- but fairly quiet and respectful. In the old days, when the national park concept was new and untried, visitors did laundry at the geysers and heated their coffee atop various "thermal features." Now, everyone seemed willing to respect the modern National Park Service refrain, Take nothing but pictures, leave nothing but footprints.

After some preliminary gurgling and spurting that sent a stir of murmured anticipation through the assembly, Old Faithful erupted at 11:27. It looked just like the postcards, a flume of water shooting 180 feet into the air and then fanning out at the insistence of a mild southwesterly breeze.

One woman clapped and yelled, "Good show!" as the 3-minute event fizzled to a close.

For some in the audience, that would be the extent of their Yellowstone moment. More roadside attractions awaited -- maybe they could reach Mt. Rushmore before dark.

Others would follow the Yellowstone roads, take to the trails and see astounding things that would make them forget Old Faithful even existed. Up the highway, around noon, a small group gathered on a boardwalk beside Great Fountain Geyser, which authorities were predicting might blow between 12:30 and 1:45.

A man crouched on the walk, staring intently at the not-so-great thermal pool and jotting figures into a small notebook. He mumbled and scribbled like those obsessives you sometimes notice in the subway. He told us geysers were his hobby, although at the moment they seemed more like his life.

Great Fountain Geyser erupts every 7 to 15 hours, so throngs seldom descend upon it, checking their watches. When it does go off, the bursts seldom exceed 150 feet, but they might persist for an hour or more.

"A superburst from this one would go up more than 200 feet," the man said. "When there's a superburst, it's the highest geyser in the world."

He said no more, just waited. At 12:45, the pool came to life, and the first eruption had the group ooohhhing and aaahhhing, as a tall plume whipped toward the sky. Just as that burst subsided, another took its place. I left half an hour later with Great Fountain Geyser still going strong and the man still jotting notes. This would not be a superburst day, but it was a highlight of the day, nonetheless.

It was an event with few witnesses in the company of a person who truly cared about the phenomenon before us. In most of the well-traveled areas of Yellowstone -- further north in the geyser basins, around the colorful geysers near the West Thumb of Yellowstone Lake, around the rim of the Grand Canyon of the Yellowstone -- buses unload and people stroll four abreast on the protective boardwalks.

Where the landscape flattened, if cars parked beside the road, that usually meant grazing deer and clicking cameras. One afternoon, along the Firehole River, we saw about 30 bison grazing on the west side of the road. Vehicles stopped, people got out and took their photographs. Then a few bison decided to cross the road, blocking traffic. A buffalo cow paused at the centerline to nurse her calf.

"That's when you try to get a shot that doesn't show the pavement and all the cars around," a lodge worker once told me. "Looks more natural."

But this was bison-RV gridlock of the first order; nobody could find such an angle, not until all the bison finally had dawdled on over to their new meadow and the mother had shaken off her child.

Yellowstone is considered the largest wildlife sanctuary in the country with a diverse population of free-ranging mammals. Now those who stay behind the windshield see mostly mule deer and buffalo, an occasional marmot and soaring osprey.

Those willing to trek a bit into the Lamar Valley, toward the park's northeast entrance, might see wolves -- newly reintroduced into Yellowstone -- or elk, pronghorn sheep and coyotes. Moose hang out in Hayden Valley, near the Yellowstone River and the canyon.

Grizzly and black bears used to congregate near the roads and the garbage dumps, looking for handouts. Cute (remember those old classroom films?) but dangerous for bears and spectators alike (dependence on humans leads to death through indigestion; aggressive bear behavior results in execution). The Park Service improved sanitation methods and cracked down on the feeding of wildlife a couple of decades ago, so people rarely see bears unless they hike deep into the wild.

National parks always reward hikers, of course. Ribbons of asphalt, fences, vehicles and other people diminish the sense of being in a completely wild place -- in this instance a place in which most of the 2 million acres have not changed much visibly since the last flow of magma -- except, of course, for the parts that succumbed to the fires.

For almost everyone, the Grand Canyon of the Yellowstone must be enjoyed in the company of others. Again, the scenery goes off in a completely different, and perhaps unexpected, direction: a 1,000-foot gash in the earth, the colorful volcanic-rock walls, the roar of a madly rushing Yellowstone tumbling over cliffs of petrified lava.

Trails follow the rim. So does a scenic motor loop. One path drops down to the very top of the lower falls -- a cool, turbulent grotto overshadowed by canyon and filled with the roar of water digging deeper into its self-made trough.

At Yellowstone, the explosions continue in some form or other. Nature yells out with almost incomprehensible energy. And everywhere we look, some kind of brilliance catches the light.