Down the Great Unknown (35 page)

Redwall Cavern itself remains exactly the immense stone clamshell that Powell saw. In some ways, the Grand Canyon has changed considerably since Powell's day. Because the dams catch the Colorado's load of mud and silt, for example, the river often runs green rather than red. Other changes show the hand of man more directly. Navajo Bridge soars overhead at Mile 4, for instance. A rustic lodge called Phantom Ranch sits at Mile 88. Test holes drilled in the cliffs at Mile 40 mark the spot where the Bureau of Reclamation intended to site Marble Canyon Dam.

Against a backdrop as enormous as the Grand Canyon, though, such signs of human intrusion are rare. For nearly all its 277 miles, the Grand Canyon looks from river level just as it did a hundred years ago, or a thousand, or a hundred thousand. Photographers have traveled throughout the Grand Canyon rephotographing the earliest pictures of it, taken shortly after Powell's first expedition. In nearly every case, trying to tell which photo was taken when Ulysses S. Grant was president and which taken only the other day is nearly impossible, a harder variant of the children's puzzles that challenge the reader to “find six differences between these two drawings.” Is that the same cottonwood tree in both photographs? What happened to that piece of driftwood? In some cases, where the river flows happened to match, photographs of the same rapid taken one hundred years apart show the identical holes in the identical places.

If Powell and his men were captured by a time machine and sent to the Grand Canyon today (at a time when the river happened to be muddy), they would see nothing for miles and miles to indicate that it was not 1869. The illusion would last until a jet passed high overhead or a raft of tourists rounded a corner. Up above, at Grand Canyon Village, the canyon's South Rim is thick with tour buses and restaurants. Down on the river, there are no buildings, no signs, no maps or trash cans, no more than a handful of human alterations to the landscape. Nearly everywhere it is many hours or days to the nearest electrical outlet. There are no camps as such, simply beaches where the river has deposited some sand.

The camping spots are pristine, scrupulously maintained by hikers and boaters who would no sooner leave a gum wrapper in the Grand Canyon than they would a Big Mac in the Sistine Chapel. Twenty thousand visitors a year travel the river and leave scarcely a sign. Commercial boatmen, in their shorts and T-shirts, are more punctilious than the starchiest English butlers; let a single blob of jelly from a sandwich fall onto the sand and someone will scoop it up and carry it off before it stops trembling. The National Park Service's river rangers scour campsites inch by inch looking for “microtrash.” A cigarette stub or a bit of candy wrapper a quarter-inch square is a major find. A river ranger will cross a churning river to retrieve a beer can he has spotted bobbing in an eddy, an act roughly akin to a trooper's darting across a six-lane highway to pick up a plastic bag snagged on the guardrail.

If rangers find signs of a campfire (fires are forbidden), they clear away the evidence to avoid giving ideas to future arrivals. Half-burnt logs are flung into the river, blackened rocks scattered, even ashes lugged away in a bucket. As in Powell's day, anyone venturing into the canyon must bring his supplies with him. (Fishing is permitted.) And just as everything must be brought in, so must everything be carried out. Every river trip carries its own “toilets”—metal boxes with the top lid temporarily removed in favor of a toilet seat. Many a river passenger pays $200 a day to ride downstream in the company of an ammo can or two of human waste.

Powell and his men had grimmer concerns than the tidiness of their campsites. They had just passed the rapids that, twenty years later, would prove disastrous for the Stanton expedition. Frank Brown, the would-be railroad tycoon, would drown just downstream of Soap Creek Rapid, at Mile 12, below Lee's Ferry. Hansbrough and Richards would drown at 25 Mile Rapid.
By the time Powell
and his men reached Redwall Cavern, at Mile 33, they had made it by Badger Creek Rapid and Soap Creek and Sheer Wall and House Rock and the nine or ten rapids that make up the Roaring Twenties.

There was no letup, and there would be none, and, as if in passing, Powell made the key observation that explained why. “A creek comes in from the left,” he wrote, “and just below, the channel is choked with boulders, which have washed down this lateral cañon and formed a dam, over which there is a fall of thirty or forty feet.” Wherever side canyons join the Grand Canyon, that is, sudden floods can dislodge boulders and unstable chunks of cliff and fling them into the main channel where they squeeze the river into abrupt, angry rapids.

Powell was the first
to figure it out, but Stanton, in the ill-fated expedition of 1889, was the first eyewitness. Stanton and his exhausted men climbed out of the Grand Canyon just thirty-two miles downstream of Lee's Ferry. Already, they had endured three drownings and countless near misses. Still to come was one final fright, a kind of parting gift from the Grand Canyon. The day before, the survivors had watched helplessly as their leader's corpse floated downstream. Now, as they hiked out of South Canyon to what they hoped was safety, the skies opened and the rain poured down in what seemed like solid sheets of water. Stanton described the scene:

As the rain increased, I heard some rock tumbling down behind us, and, looking up, I saw one of the grandest and most exciting scenes of the crumbling and falling of what we so falsely call the everlasting hills. As the water began to pour over from the plateau above, it seemed as if the whole upper edge of the Canyon had begun to move. Little streams, rapidly growing into torrents, came over the hard top stratum from every crevice and fell on the softer slopes below. In a moment they changed into streams of mud, and, as they came farther down, again changed into streams of water, mud and rock, undermining huge loose blocks of the harder strata, and starting them they plunged ahead. In a few moments, it seemed as though the slopes on both sides of the whole Canyon, as far as we could see, were moving down upon us, first with a rumbling noise, then an awful roar. As the larger blocks of rock plunged ahead of the streams, they crashed against other blocks, lodged on the slopes, and, bursting with an explosion like
dynamite, broke into pieces, while the fragments flew into the air in every direction, hundreds of feet above our heads, and as the whole conglomerate mass of water, mud, and flying rocks came down the slopes nearer to where we were, it looked as if nothing could prevent us from being buried in an avalanche of rock and mud.

This was a debris flow. Powell and his men had never seen such a thing, but they would come to recognize its signature all too well, for in the Grand Canyon it is debris flows that make rapids. A debris flow is a kind of thick mud river, like an enormous, slow-motion avalanche made of wet concrete. Because it is so viscous and so powerful, a debris flow can dislodge and carry boulders that a flash flood could never budge. Boulders and trees slide and tumble and spin along helplessly as the flow snags them and drags them downhill. Some accounts describe “car-sized objects” riding atop the flow, but reality is more dramatic. Cars generally weigh under two tons; in 1990, a debris flow in the Grand Canyon swept a 280-ton boulder into the river.

John McPhee described a recent debris flow in Los Angeles. A house sat in its path:

The parents' bedroom was on the far side of the house. Bob Genofile was in there kicking through white satin draperies at the panelled glass, smashing it to provide an outlet for water, when the three others ran in to join him. The walls of the house neither moved nor shook. As a general contractor, Bob had built dams, department stores, hospitals, six schools, seven churches, and this house. It was made of concrete block with steel reinforcement, sixteen inches on center. His wife had said it was stronger than any dam in California. His crew had called it “the fort.” In those days, twenty years before, the Genofiles' acre was close by the edge of the mountain brush, but a developer had come along since then and knocked down thousands of trees and put Pine Cone Road up the slope. Now Bob Genofile was thinking, I hope the roof holds. I hope the roof is strong enough to hold. Debris was flowing over it. He told Scott to shut the bedroom door. No sooner was the door closed than it was battered
down and fell into the room. Mud, rock, water poured in. It pushed everybody against the far wall. “Jump on the bed,” Bob said. The bed began to rise. Kneeling on it—on a gold velvet spread—they could soon press their palms against the ceiling. The bed also moved toward the glass wall. The two teen-agers got off, to try to control the motion, and were pinned between the bed's brass railing and the wall. Boulders went up against the railing, pressed it into their legs, and held them fast. Bob dived into the muck to try to move the boulders, but he failed. The debris flow, entering through windows as well as through doors, continued to rise. Escape was still possible for the parents but not for the children. The parents looked at each other and did not stir. Each reached for and held one of the children. Their mother felt suddenly resigned, sure that her son and daughter would die and she and her husband would quickly follow. The house became buried to the eaves. Boulders sat on the
roof. Thirteen automobiles were packed around the building, including five in the pool. A din of rocks kept banging against them. The stuck horn of a buried car was blaring. The family in the darkness in their fixed tableau watched one another by the light of a directional signal, endlessly blinking. The house had filled up in six minutes, and the mud stopped rising near the children's chins.

Debris flows are rare because they require, simultaneously, torrential rains and cliff sides poised to collapse. But even rare events happen sooner or later, and the Grand Canyon has all the time in the world. Start with that abundance of time, add the canyon's endless cliffs, stir in its dramatic rainstorms, and you have a recipe for debris flows. And, accordingly, nowhere else in North America have debris flows shaped the landscape as they have in the Grand Canyon.

The first lesson for geologists is that the classic picture of erosion nibbling the canyon walls away grain by grain is wrong. The true picture is not one of crumbling rocks but of crashing boulders, as rare but violent storms take great bites from the canyon's flanks. “Debris flows move entire slopes,” writes the geologist Robert Webb, “not just individual grains of sand.” A second lesson is that the Grand Canyon is, for now, in equilibrium, a battleground for two stalemated opponents. Tiny sidestreams, aided by debris flows, throw boulders into the main channel. Even the mighty Colorado has only a certain amount of energy to expend, and the river is using its energy not on cutting a deeper channel for itself but on eroding and removing the boulders choking its path. When the climate changes again, one warring side or the other may gain an advantage, but for now the canyon's depth is unchanging.

For river runners, those geological insights pale next to a more practical one—debris flows make rapids, and the Grand Canyon is ideal spawning ground for debris flows. Powell had seen that rapids
could
form in this way, but the truth was far worse than he realized. The Grand Canyon is joined by countless side canyons, every one of them guaranteed, sooner or later, to fling its river-choking cargo into the Colorado's path. For Powell and his weary men, that meant an endless series of rapids.

•      •      •

On August 10, the men advanced only fourteen miles but encountered thirty-five rapids. “We run them all though some of them were bad ones,” Bradley wrote. “One was the largest we have run in the Colorado for we have gone more cautiously in it than we did in the Green.” Bradley had complained throughout the trip that Powell insisted too often on hauling the boats around rapids, and he had not changed his mind. At first he had argued that portaging and lining were difficult and dangerous and unnecessary. Later he complained that they wasted precious time (and therefore precious food). Those objections still held, and now Bradley added one more. “I think we have had too much caution and made portages where to run would be quite as safe and much less injurious to the boats.”

At two o'clock in the afternoon, the expedition reached the Little Colorado, a tributary of the Colorado that the men also called the Chiquito or the Flax. They were not impressed. “It is a lothesome little stream,” Bradley wrote, “so filthy and muddy that it fairly stinks. It is only 30 to 50 yds. wide now and in many places a man can cross it on the rocks without going in to his knees.” Sumner's judgment made Bradley's sound like a love poem. The Little Colorado was “as disgusting a stream as there is on the continent . . . half of its volume and 2/3 of its weight is mud and silt.” It was little but “slime and salt,” “a miserably lonely place indeed, with no signs of life but lizards, bats, and scorpions. It seemed like the first gates of hell. One almost expected to see Cerberus poke his ugly head out of some dismal hole and growl his disapproval of all who had not Charon's pass.”

The mud that so revolted Bradley and Sumner was runoff from summer thunderstorms. In dry weather, the Little Colorado runs a brilliant, tropical blue (because of calcium and sodium and other dissolved minerals). The green Colorado and the blue Little Colorado run side by side for a time, independent ribbons of color like stripes on a flag.

In rainy weather, the Little Colorado runs muddy. Unlike Powell's men, modern tourists tend to revel in the mud, as if the river were a mud bath at a posh spa. They splash in the goop like puppies, reveling in the warmth after the Colorado's iciness. (The water released into the Colorado at Glen Canyon Dam comes from two hundred feet below the surface of Lake Powell and is a painful forty-eight degrees. Just splashing water on your face to wash up takes an effort of will. Holding your head underwater long enough to wash your hair actually hurts. Hypothermia can become severe in five minutes. For those who fall off their boat, it is a greater risk than drowning. Often the two work in tandem, for a person plunged into cold water immediately begins to hyperventilate, and the desperate, reflexive attempts to catch one's breath may lead instead to swallowing great mouthfuls of water. )