Down the Great Unknown (34 page)

Dinosaurs provided the public with further proof that the earth had a long history, and the first decades after the Civil War were the great age of dinosaur discovery. Scientists roaming the West stumbled over dinosaur bones at every turn. At one site in Wyoming, bones of bygone creatures lay so thick on the ground that a sheepherder used them to build a cabin. During a brief stop at an isolated train station in Nebraska in 1868, a Yale scientist took a moment to examine a jumble of bones unearthed by someone digging a well. He recognized them as coming from ancient ancestors of the modern horse. A discovery made while an impatient conductor held the train proved to be one of the great finds in the history of science.

But, on a geologic scale, the first dinosaurs stumbled to their feet only the other day.
The oldest rocks
in the Grand Canyon, in contrast, are nearly two billion years old, not quite half as old as the earth. On a timeline where the history of the earth is compressed to a single year, dinosaurs show up only in mid-December and vanish on December 26. (Humans make their appearance on the evening of December 31. Columbus discovers America at three seconds before midnight.)

The first white men to peep over the rim of the Grand Canyon were Spanish conquistadors, in 1540, led by Hopi guides. (For more than two hundred years afterward, no whites returned.) The Spaniards could make no sense of what they were seeing. The conquistadors' “discovery” of the Grand Canyon, one early writer scoffed, was “akin to a dog's discovery of the Moon.” A few agile conquistadors tried to climb down to the river, but they gave up after making it about one-third of the way. “From the top they could make out, apart from the canyon, some small boulders which seemed to be as high as a man,” Pedro de Castañeda reported. “Those who went down and who reached them swore that they were taller than the great tower of Seville.”

It is hard to place ourselves in the position of those who encountered the Grand Canyon unprepared by countless descriptions and pictures. For the modern traveler, familiarity breeds, if not contempt, then complacency. No early visitor tiptoeing to a canyon rim responded with anything but awe. Consider, for example, this description of the Grand Canyon of the Yellowstone, a petite version of the Grand Canyon of the Colorado. The writer was Nathaniel Pitt Langford, a brave and adventurous explorer and one of the first white men to describe what is now Yellowstone National Park. He wrote in 1870, a year after Powell's exploration of the Grand Canyon.

“Standing there or rather lying there for greater safety,” Langford recalled, “. . . I realized my own littleness, my helplessness, my dread exposure to destruction, my inability to cope with or even comprehend the mighty architecture of nature. . . . A sense of danger, lest the rock should crumble away, almost overpowered me. My knees trembled, and I experienced the terror which causes men to turn pale and their countenances to blanch with fear, and I recoiled from the vision I had seen, glad to feel the solid earth beneath me.” Langford was clinging to a spot of ground tourists now know as Inspiration Point.

Canyons stunned their first eyewitnesses partly because their size is so far beyond human scale. The Grand Canyon especially, at a mile deep, ten miles across, and nearly three hundred miles long, dwarfs all who would take its measure. But size is only part of the story. Unexpectedness plays just as large a role. Mountains are miles high and the ocean is seemingly infinite, but they announce their presence from a distance. The sight of a snowy peak or the tang of an ocean breeze beckons the traveler.

From an airplane, where even the Grand Canyon looks like a gash ripped in the earth, the view makes a kind of sense. From river level, as Powell and his men had seen, a canyon emerges gradually, unfolding over the course of days and weeks. But approached on foot, a canyon is a shock. Until the last moment, there is no hint of anything special in the neighborhood—park rangers at the Grand Canyon are asked, over and over again, where the canyon is—and then, suddenly, the ground disappears from before one's feet.

The Grand Canyon proclaims, with the force of a slap to the face, “This is
very
old.” Curiously, that message is only half right. The rocks that the canyon reveals are billions of years old, but the canyon itself is young. This is no paradox. A tree might be hundreds of years old, but the axe cut that revealed its rings might have been made only yesterday.

The Grand Canyon is somewhere between four and six million years old. Geologically speaking, to be a mere five million years old is to be barely out of diapers. (In that short time, the river has carried away all the rock that once filled the canyon rim to rim. Before the dams were built, the Colorado carried an average of five hundred thousand tons of sand and silt—enough to fill a line of pickup trucks stretching the full width of the United States—past a single point
every day
. It is no wonder that the river ran red and muddy.)

“The most emphatic lesson that the canyon teaches,” observed the geologist William M. Davis, one of Powell's disciples, “is that it is not an old feature of the earth's surface but a very modern one . . . It is properly described as a young valley.” If the Grand Canyon were truly old, Davis explained, it would hardly be worth going to see. In time, as erosion continues on its relentless course, “the main canyon shall slowly wear deeper and deeper, and the side canyons, increasing in length and width, shall consume the entire plateau, hundreds of miles north and south of the river, and thus the whole region shall be reduced to a featureless lowland but little above sea level.”

Most of the Grand Canyon is an enormous layer cake (or, more precisely, a hole cutting through an enormous layer cake). The individual layers are hundreds of feet thick and have formed over tens of millions of years. The deeper the layer, the older, like the clothes on a teenager's bedroom floor. The changes from one layer to another testify to a landscape that has changed again and again through the ages.

The Coconino Sandstone, for instance, is near the rim and therefore young. A mere 200-odd million years old, it is a remnant of a former desert, an eternity of blowing sand dunes now glued in place. But what was once a desert has also been a coastal plain and the site of a warm, clear sea. The Hermit Shale, which sits beneath the Coconino Sandstone, was laid down by rivers dropping their loads of silt and mud at what was once a seacoast. The five-hundred-foot-thick Redwall Limestone is formed, in part, of countless tiny seashells that rained gently down onto the ocean floor three hundred million or four hundred million years ago.

More is gone than remains. If the Grand Canyon is a journal recording earth's history, vandals have torn out over half the pages. At one juncture that Powell named “
the Great Unconformity
,” layers of rock that differ in age by 1.2 billion years lie one atop the other. All the intervening years have eroded away without a trace. It was another of Powell's pet themes. “Beds hundreds of feet in thickness and hundreds of thousands of square miles in extent, beds of granite and beds of schist, beds of marble and beds of sandstone, crumbling shales and adamantine lavas have slowly yielded to the silent and unseen powers of the air, and crumbled into dust and been washed away by the rains and carried into the sea by the rivers.” Someone left the cake out in the rain.

We can see those layers and deduce their history because the Colorado River has sliced its way downward inch by inch through thousands of feet of rock. “The finest workers in stone are not copper or steel tools,” wrote Thoreau, “but the gentle touches of air and water working at their leisure with a liberal allowance of time.”

Even more so when those touches aren't so gentle. The Colorado cuts down as it flows not simply because the water is moving but also because the river carries a swirl of rocks and pebbles and grit that help it abrade its way. (For similar reasons, stonecutters in quarries use abrasive-coated wire blades to cut blocks of stone.) The cutting does not proceed at a steady pace. For much of the year, the rocks and sand may sit in place on the river bottom. Come the spring thaw or a sudden flood, though, and the river grinds those rocks against the channel bottom. Multiply by ten thousand centuries and you have a canyon.

The river's sawing is only part of the story. The Grand Canyon is so deep because it is part of an immense geological formation called the Colorado Plateau, which has been soaring upward while the river has been cutting its channel. The entire plateau, which straddles the Four Corners region where Utah, Colorado, New Mexico, and Arizona meet, has risen one thousand feet in just the past million years. Picture, Powell said, a buzz saw spinning in place while the log it was cutting rose up: “The river was the saw which cut the mountains in two.” (And the canyon is so wide—rather than merely as wide as the river itself—because erosion bites into its exposed sides.)

For Powell and his fellow geologists, all this was irresistibly exciting. In the nineteenth century, the West was a geologic boomtown. Geology in Europe and back East was far more difficult because the landforms there had been squeezed and twisted into almost unfathomable shapes and then hidden by trees and bushes and grass. What was elsewhere concealed by vegetation was here stripped bare. Better yet, Grand Canyon country was a region of neat layers resting tidily one atop another, color-coded, hundreds of feet thick, and extending for hundreds of miles. Best of all, the landscape was neatly sliced open by canyons that served geologists as dissecting kits served anatomists.

Old World geologists could scarcely conceal their envy of their counterparts in the American West. “The history of the rocks there is so simple,” one British geologist complained when he learned of Powell's findings, “that a child could read it.”

This was partly true and partly sour grapes, for the challenge of the Grand Canyon is as much psychological as intellectual. The river is barely visible from the rim. Where the Colorado does appear, glinting in the desert sun, it seems tiny and insignificant. (The Spanish conquistadors had estimated that it was six feet wide.) “It looks about large enough to turn a village grist-mill,” observed Clarence Dutton, the great nineteenth-century geologist, “yet we know it is a stream three or four hundred feet wide. Its surface looks as motionless as a lake seen from a distant mountain-top.” How could this placid stream cleave five thousand feet of rock?

For Powell and his weary men, who were battling the river on a daily basis rather than squinting to make it out in the distance, it did not take a leap of imagination to believe in the Colorado's power.

CHAPTER TWENTY-ONE

THE GREAT UNKNOWN

 

Late in the afternoon of August 8, after an exhausting day of portaging, Powell's men dragged themselves into camp and collapsed. The roar of a rapid just downstream promised that the next day would be another ordeal. A second rapid loomed about five hundred yards beyond the first one, “but we can't get down to look at it,” Bradley wrote, “for the walls come down to the water and it is too deep and swift to wade past it.” The trap was squeezing shut.

Powell was happily studying the scenery, but Bradley had no time for such distractions. Restless and jumpy, he found himself veering back and forth between frank confessions of dread and hearty proclamations of confidence. “We are interested now only in how we shall get through the cañon and once more to civilization though we are more than ever sanguine of success. Still our slow progress and wasting rations admonish us that we have something to do. Fortunately we are a happy-go-lucky set of fellows and look more to our present comfort than our future danger.”

That “comfort” didn't amount to much. They were all stuck “in a cave of the earth,” Bradley complained, trying to look forward with anticipation to a breakfast of beans that Hawkins had promised for the next morning. The “future danger,” on the other hand, was all too real. “Hard at work early,” Sumner wrote the next day, August 9. “Made 4 portages and ran 27 bad rapids in 13 miles.” The rapids were “furious,” Bradley wrote, though he recorded his customary hopes that “this series of heavy rapids is about ended.”

Not all the sights were ominous. “The river turns sharply to the east,” Powell wrote, “and seems enclosed by a wall, set with a million brilliant gems. What can it mean? Every eye is engaged, every one wonders. On coming nearer, we find fountains bursting from the rock, high overhead, and the spray in the sunshine forms the gems which bedeck the wall. The rocks below the fountain are covered with mosses, and ferns, and many beautiful flowering plants.” (And poison ivy, as modern tourists have learned.)

It was, Sumner agreed, “the prettiest spring I ever saw.” Powell named the spot Vasey's Paradise, in honor of a botanist who had traveled in the Rocky Mountains with him the year before. Struck by the welcome burst of greenery against “the unending barrenness of the cañon,” Bradley lauded it as “the prettiest sight of the whole trip.” Sumner, characteristically, downplayed his own enthusiasm. “The white water over the blue marble made a pretty show,” he conceded. “I would not advise anybody to go there to see it.”

Only two miles downstream they came to another spectacular site, now called Redwall Cavern. “The water sweeps rapidly in this elbow of river, and has cut its way under the rock, excavating a vast half circular chamber,” Powell wrote. The space, “if used for a theater, would give sitting to fifty thousand people.”

No theater could have a more spectacular setting, though Powell exaggerated its size perhaps tenfold. Today, with the Colorado dammed, the undercutting that formed the cavern is at an end. (In the flood year of 1983, though, river runners floated deep inside the cavern and tied up to its ceiling.) For boatmen and passengers on the Colorado today, Redwall Cavern provides a welcome chance to leave the cramped confines of the boats and run and play on the vast sandy beach. No sooner has the first boat tied up than the Frisbees start flying. Where Powell and his hungry, fearful crew gawked in wonder, tourists in cutoff dungarees and Day-Glo bathing suits roam the beach and slather suntan lotion on their peeling skin and decide if it's late enough in the day to crack open a beer.