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"Rafting Through the Grand Canyon"

PBS Airdate: July 22, 1997

ANNOUNCER: Tonight on NOVA, shoot the wild rapids and explore the world's greatest geological treasure, the Grand Canyon. Towering layers of rock and deep gorges reveal secrets of the earth's past, telling tales of ancient oceans and fiery volcanoes. Gregory Peck and Linda Hunt bring to life the breathtaking story of the man who first dared to run the Colorado River. "Rafting Through the Grand Canyon."

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GREGORY PECK: The Grand Canyon of the Colorado is composed of many canyons. There are thousands of gorges like that below Niagara Falls, and there are a thousand Yosemites. Yet, all these canyons unite to form one Grand Canyon, the most sublime spectacle on the earth.

LINDA HUNT: More than a century ago, this dramatic description from the diary of explorer John Wesley Powell brought the Grand Canyon to the world. And, having heard the news, the world came to the Grand Canyon. From the first visitor to the present day, millions have gone to extraordinary lengths to take in the world's most famous view. In fact, a new kind of creature may have been born here, the nature tourist. Part of the attraction here is that the Grand Canyon reveals the inside story of the ground that lies beneath our feet. Here, lying open a mile deep, is the vault of Earth's history, a chasm whose walls of layered rock tell the tales of two billion years in the life of the planet. Nowhere else in the world can a visitor take in so much time with a single glance. But to get to know the Grand Canyon, you have to explore it not only from high on the rim, but from down below, on the Colorado River. Running the river through the Grand Canyon is not only a whitewater adventure, it's also a real world journey back through time.

LINDA HUNT: The trip begins here, at Lee's Ferry, Arizona. We'll travel down the river for a week, in the company of some veteran canyon geologists. This group is from the Kansas Geological Survey, and their director is Lee Gerhard.

LEE GERHARD: You all have shirts and hats coming. Tom's got them.

FIRST MEMBER: Good job, Otis.

OTIS: Thank you.

FIRST MEMBER: Looking good.

OTIS: It's hard to do under pressure. (laughter)

LINDA HUNT: Pushing off in this boat are members of the Geological Society of America, a professional organization for geologists. For these river runners, a trip through the canyon is the ultimate busman's holiday, a chance to relax while exploring the best geological display in the world. They'll travel 280 miles downstream, measuring their distance from here, at Lee's Ferry, mile zero on the canyon's map. The Colorado River begins high in the Rocky Mountains, and gathers force from the Green River and the San Juan as it flows southwest. Then, it slices through the Grand Canyon, located in the northeast corner of Arizona. In Nevada, the river turns south, finally emptying into the Gulf of California. Not far from Lee's Ferry, we encounter the first of the canyon's famous rapids. There are 160 altogether. It's a roller-coaster ride, and a good soaking is part of the experience. But with canyon temperatures in the high 80s, no one seems to mind a little cooling off. There's plenty of wildlife to see along the way, like this Bighorn sheep. But what is most striking to river travelers is how the rock layers change. The river takes us on a kind of downward escalator, cutting diagonally into the earth's crust. Here, pink sandstone rests on top of a much darker rock called the Hermit shale. Downstream seven miles, the same Hermit shale we just saw at river level is now 500 feet high on the canyon wall. The first hike will be up to the North Canyon, one of the many beautiful side canyons within the Grand Canyon. But how did all these layers of rock get here in the first place?

IVO LUCCHITTA: Well, one of the remarkable things about the Grand Canyon is this great sequence of layered rocks, which the visitor sees from the rim typically, and which are made of sand and pebbles such as these, that are laid down, brought in by water or by wind, deposited and then consolidated by pressure from overlying rocks such as those. And the result of this is a sandstone that looks very much like this. This is a good example of a sandstone. Or you can also have marine organisms whose little skeletons accumulate with time and are also made into hard rock by time and pressure.

LINDA HUNT: These unimpressive bits are compressed into what are called sedimentary rocks, the main building blocks of the Grand Canyon. The particles are carried by wind or water until they arrive at a stable place where they can settle out. Over time, they are covered by more layers of sediment until finally, the buried layers harden into rock. Each rock, by the type of particles it contains, tells the story of its own origin. Sand becomes sandstone, the skeletons of sea animals become limestone, mud becomes shale. The best place to see the canyon's entire collection of rock layers is up at the rim. These walls tell tales of many lost worlds, ancient seas, deserts, and even volcanoes, once in this very spot, long before the canyon formed.

GENE SHOEMAKER: The Grand Canyon is like a book of geology. The individual layers of sedimentary rock are the pages in this book, and the pages are arranged in chapters that could be traced for hundreds of miles along the canyon walls. At the top of the distant rim, you can see the Kaibab formation, and that records the deposits laid down at the bottom of a shallow sea. And below, you can see a white band which is the Coconino formation, which is composed of fossil sand dunes that were laid down beneath a desert before the sea came in. Here's a piece of the Coconino sandstone, which records a little bit of history of the animal life. This was actually on the steep slip face of a sand dune, and a small reptile about the size of a modern lizard scampered up the sand slops, probably when it was wet, leaving these impressions. You can tell which way is downhill here. And you can see that he pushed down on the sand a little bit as he climbed the sand dune.

LINDA HUNT: These layers at the rim, which turned to rock just before the age of dinosaurs, are the canyon's youngest formations. There are 21 distinct layers of rock here, each one representing a package of about 30 million years of time gone by. As we cast our gaze down the canyon walls, we're looking at older and older rocks. In the deepest part of the canyon, the rocks are 1.7 billion years old, a third as old as the Earth itself. Rocks not only carry the story of their origin, they also reveal what has happened to them since they were deposited. This valley in North Canyon was once solid rock, weighed down by enormous pressure from the layers above. When a stream cut this side canyon, releasing the pressure, the rock took on a new shape.

IVO LUCCHITTA: These interesting features that we see in this massive sandstone, these curved planes that then form this lovely U-shaped valley, are the result of the sandstone being subjected to a great deal of pressure from the overlying column of rocks and then this pressure being released by the carving of the canyon, so that the sandstone expands towards the free surface, and cracks and forms these joints.

LINDA HUNT: Given enough time, all rocks, no matter how settled they may appear, are subject to change. Like Ten-Mile Rock, a slab of limestone that toppled off the canyon's rim, burying itself in the riverbed like a great hatchet. Such rockfalls may happen once in a millennium. Today, a trip through the canyon is an adventure, but it could hardly be considered dangerous. A century ago, for those who first dared to make this journey, it was a different story. Just after the Civil War ended, an obscure Union Army officer, Major John Wesley Powell, set his sights on a great adventure.

GENE SHOEMAKER: When Powell came on the scene, it was just at the time of several great scientific exploring expeditions of the West, and there was one large blank spot left on the map of the United States, which was that Colorado Plateau. And of course, right through the middle of it ran the Colorado River, which had never been run. And Powell resolved to fill that blank space.

LINDA HUNT: The 35-year-old Powell had lost his right arm at the battle of Shiloh, but this did not stop him from planning an ambitious 1,000-mile river journey across the Colorado Plateau. He sought the advice of the Paiute tribe and other Native Americans in the region, who warned it couldn't be done. Powell remained undaunted. He put together a crew of nine mountain men and, on May 24th, 1869, the expedition set out in four wooden boats from Green River Junction, Wyoming. On June 9th, one boat split to pieces at Disaster Falls, and much of the team's food, clothing, and scientific instruments were lost. Powell pressed on. But the signs of strain show through in his journal.

GREGORY PECK: August 13th. We have but a month's rations remaining. The flour has been resifted. The spoiled bacon has been dried, and the worst of it boiled. The sugar has all melted and gone on its way down the river. We have an unknown distance yet to run, an unknown river to explore. What falls there are, we know not. What rocks beset the channel, we know not. The men talk as cheerfully as ever. But to me, the cheer is somber, and the jests are ghastly. The river turned sharply to the east, and seems enclosed by a wall set with a million brilliant gems. We find fountains bursting from the rock high overhead, and the spray in the sunshine forms the gems which bedeck the wall.

LEE GERHARD: This is Vasey's Paradise. It's a garden spot in the canyon. It's where John Wesley Powell first found the fresh water springs coming in that allowed him to have water without silt in it, the sight of green after almost a desert-like traverse down the canyon to this point, and what he found here was then a spot to rest. And he could rest and look out across the canyon to the limestones that were deposited in a vast ocean. The bands in the rocks that we can see, dark and light, represent rises and falls of sea level. The dark beds are probably really muddy. The light beds are probably skeletal sand, that is, made up of the remains of marine organisms that have been wave-washed and otherwise broken, and then cemented into rock.

GREGORY PECK: All about me are interesting geologic records. The book is open, and I read as I write.

LINDA HUNT: More than a mere adventurer, Powell was a man of restless intellectual energy. He had taught himself geology, and now set out to explain how the Grand Canyon had formed. Geologists today are amazed at how close he came to getting it right without the help of sophisticated instruments.

STANLEY BEUS: When Powell came through the canyon, he recognized one of the puzzles about how the river got across there, and how it cut the great canyon. And he interpreted it to have started at the top and cut down as the land rose against it, sort of the analogy of cutting a cake with a knife by holding the knife still and raising the cake against the knife. We now know that the history is not that simple, but it's partly correct. So, he had the right idea, even though the dates and the timing were not entirely correct as he understood them.

LINDA HUNT: Today, more than a hundred years later, scientists still argue the details of precisely how and when the canyon was created. The mystery may never be completely solved, because the river, like a master criminal, carried off the clues as it carved the canyon. Many geologists now think it happened something like this. All of the Earth's oceans and continents ride upon enormous pieces of the Earth's crust called plates, which fit together like a restless jigsaw puzzle, jostling each other at the edges. Eighty million years ago, two of these plates collided at North America's West Coast. The Pacific plate slid under the North American plate, creating the Rocky Mountains and, ultimately, forcing the uplift of the whole Colorado Plateau. By 30 million years ago, the ancestral upper Colorado River was flowing lazily over the Colorado Plateau. But where it ended up remains a mystery. Five million years ago, the sea swept in and created the Gulf of California, offering a faster escape route. A new river sprang up in the south, claiming the gulf as its outlet, and eroding its way back upstream, where it captured the upper Colorado River's flow. The combination of this mighty new Colorado River, flowing over the already rising plateau, created a geological buzz saw, a deep groove from which the river could not escape. Many scientists now think it took only about four million years for the Colorado River to carve the canyon. Compared to the rocks and its walls, some nearly two billion years old, the canyon itself is a relative youngster. But the river's buzz saw can account for only a narrow gash in the Earth, and in places, the rims of the Grand Canyon are 18 miles apart. How did the canyon get so wide?

GENE SHOEMAKER: It's important to understand that the river, by itself, did not carve this canyon. The river did cut down its own channel, but basically, it's a transportation system. It's the freight train that carried all the rest of the rock out. And the canyon was widened out by all of the side streams and all the little rivulets that are carving into the canyon wall. It's not the river that made the great, wide canyon that we see, but all the tributary drainage systems that led to the carving of the canyon.

LINDA HUNT: Side streams and tributaries flow into the main Colorado River, gouging out their own side canyons, like this one. When there's a violent storm, truck-size boulders tear loose from the canyon walls, and are driven headlong in a terrifying wall of mud and rock called a debris flow. Seldom are human beings in a position to film debris flows. Usually, they are running for their lives to high ground. This rare footage of a debris flow sweeping through a dry valley was also shot by scientists in China in 1990. Traveling 20 miles per hour, the flow packs the power of a river of liquid concrete. GENE SHOEMAKER: The changes in the canyon country do not occur by the gradual grain-by-grain wearing away of the countryside, as so often portrayed in the geology texts. But rather, most of the time, hardly any change is taking place at all, and then when it does occur, it occurs as a sequence of major catastrophes, local catastrophes, which occur with a frequency of about once every thousand years. And that, I think, is in fact the way most geological changes happen. Not just here in the canyons of the Colorado, but generally in the landscape of the Earth.

LINDA HUNT: Here in the canyon, such debris flows rip out of side canyons, like this one, finally emptying into the main stem of the Colorado. Just downstream of the side canyons, the gravel and boulders collect, forming a kind of rock dam that chokes off the river's flow and creates a rapid. The challenge for river runners here is that the Colorado drops 2,100 feet as it travels through the canyon. And half of that drop happens at the rapids. We rejoin the GSA group as they approach one of the canyon's more notorious rapids. Hance Rapids is also known as the Rock Garden. The boatmen will pull over to have a look.

ASSISTANT: What about these down here, when we get in?

JOHN STONER: Well, you don't want to get that far left.

ASSISTANT: Yeah, right about where he is?

JOHN STONER: You want to be on this side of the rowboat.

ASSISTANT: This side of that rock.

JOHN STONER: We're right above Hance Rapid, and I want to scout this rapid for my run, and I'm looking at where the rocks are in the channel. I want to see where the tongue's at, and I'm going to be heading into the tongue, coming down into what's called a duck pond. There's some real still water, and I want to get in that. It gives me a chance to slow down and reassess my situation, so I can look downriver and set up for the run down below. It's one of the steepest drops along the Colorado River system, and at this stage, it's low water, there's a lot of rocks in the channel, and it's—I have a lot of respect for this rapid. OK, he's doing the motor run. And he might not have enough power to get back to the left, and it could be pretty interesting, hitting these holes. He's just, he's going to—See that rock sticking up right there?

ASSISTANT: Yeah. Right.

JOHN STONER: There's a big hole, just left of it, that he's going to go over.

ASSISTANT: Right. There.

JOHN STONER: Right there. There he goes. OK, he's setting himself up for the big hole down below, and he might flip it right there.

ASSISTANT: There it is.

JOHN STONER: Oh...!

ASSISTANT: He's in there.

JOHN STONER: He's surfing up.

ASSISTANT: Oh! He's swamped, but he's out.

JOHN STONER: Oh, he flopped it out!

ASSISTANT: He did. That was close.

JOHN STONER: I don't believe it! He flopped it out. He almost lost it.

ASSISTANT: He did. He was surfing in there.

JOHN STONER: All right! Whew! That gets my blood stirred.

ASSISTANT: Mine, too.

JOHN STONER: Let's get out of here.

ASSISTANT: Yeah, let's go. Let's run it.

JOHN STONER: Agh! Yow!

LINDA HUNT: This is boatman John Stoner's 130th trip down the Colorado. And some of us are glad.

FIRST TRIP MEMBER: What a great day, huh?

SECOND TRIP MEMBER: Oh, yeah. It's a beautiful day, good rapids. Good run.

FIRST TRIP MEMBER: Good timing, and away from the tail. Just right down the middle, right through all of it.

THIRD TRIP MEMBER: You know, the last set were hard. The big ones were fun. I guess you were most prepared.

FIRST TRIP MEMBER: Oh, yeah.

THIRD TRIP MEMBER: But the little ones, those little teeny things, you're right in your seat!

LINDA HUNT: Next morning, rounding the bend at mile 31, we come to Stanton's Cave, first described in 1889 by explorer Robert Stanton. Here, archaeologists have collected the oldest human artifacts yet discovered in the Grand Canyon. Small animal figures, fashioned out of willow twigs 4,000 years ago by people known as the Desert Culture. It's thought these figures may have been used during religious ceremonies to pray for a good hunt. Later inhabitants of the canyon were the legendary Anasazi people, ancestors of modern pueblo peoples like the Hopi. Here in the fertile Nankoweap Delta, Anasazi farmers grew squash and maize, storing their harvests high in a cliffside granary, safe from rodents and thieves. Spanish conquistadors were the first Europeans to arrive at the rim of the Grand Canyon, in 1540. They gazed across the terrifying abyss and saw what appeared to be only a small stream. The party could find no way to make the steep descent to the canyon floor, and turned back. Then, in 1857, an attempt was made to sail a steamboat up the Colorado River from the south. After two months, Lieutenant Joseph Christmas Ives gave up. Comparing the canyon to the gate of Hell, he wrote, "After entering it, there is nothing to do but leave. Ours has been the first, and will doubtless be the last party of whites to visit this profitless locality. It seems intended by nature that the Colorado River shall be forever unvisited and undisturbed." Thirty-three miles downstream of Lee's Ferry, we come to Red Wall Cavern, named by John Wesley Powell and his men when they camped here. It's a vast limestone chamber carved by the river as it flowed around the bend. And it's ceiling is over 100 feet high. For river runners today, Red Wall Cavern is a favorite afternoon stop. Later in the day, we make an early camp, and tonight, the tales around the Kansas Geological Survey's campfire are told by the great grand-nephew of John Wesley Powell himself, Donald Powell Schnacke.

DONALD POWELL SCHNACKE: The unique thing about John Wesley Powell was that he was never, never satisfied when he would land at a place like this in the afternoon. He was always curious on what was upstairs, and so he'd skinny up the rocks and go to the top and look around. And many times, he would stay up there and come down after dark. And if you can imagine coming down one of these cliffs in the dark with one arm, that was a feat in itself.

GREGORY PECK: Standing on my toes, my muscles begin to tremble. It is 60 or 80 feet to the foot of the precipice. I find I can get up no farther, and cannot step back, for I dare not let go with my hand. I call to Bradley for help. At this instant, it occurs to Bradley to take off his drawers and swing them down to me. I seize the dangling legs, and with his assistance, gain the top.

LINDA HUNT: It's a tricky climb up to Nautiloid Canyon, but for those who make the effort, a ghostly marine treasure awaits.

STANLEY BEUS: We're now sitting on the floor of the Nautiloid Canyon, which is in the Red Wall limestone, making the great walls of the canyon around us. The Red Wall limestone is a marine deposit formed in a shallow sea many millions of years ago. And we know that because right here is one of those marine shells. I'm going to pour some water on it so that it shows better. This is the outline of a nautiloid shell. It had a long stovepipe sort of cylindrical shell, with curved partitions across it, and it's related to the modern chambered nautilus, which currently lives in the Indian Ocean, except these had straight shells and the chambered nautilus has coiled shells.

LINDA HUNT: Meet the nautiloids' modern descendant. Three hundred million years ago, a vast shallow sea like this one covered not only the Grand Canyon region, but much of what is western North America today.

STANLEY BEUS: It's hard to imagine all of the things that have gone on in this place, but the Grand Canyon record tells us of mountain ranges, seas that have advanced and retreated at least 18 times across Arizona, a variety of the coastal swamp conditions, desert dunes. And all of these marvelous things have happened in this place over a period of two billion years, and they are recorded in the Grand Canyon record.

LINDA HUNT: We head on downstream for lunch with members of the Kansas expedition. They are fishing for rainbow trout, a species that was introduced here in 1964. A former governor of Kansas, Mike Hayden is among old friends on this trip. A year ago, he became assistant secretary of the U.S. Department of the Interior, which oversees the Grand Canyon National Park.

MIKE HAYDEN: Our national park system is designed with long-range goals of protection, conservation of the environment and of the ecosystems for all time. Not only for this generation, but for future generations, we trying to make sure that these ecosystems are healthy for our grandchildren's children as well.

LINDA HUNT: There has been a big change since the days of John Wesley Powell, when man was at the mercy of nature in the canyon. Today, the major force of change here is man himself, for the past century has brought intensive development of the Colorado River for irrigation and hydroelectric power. There is a classic struggle going on here between conservation and development, a story that began back in the early years of the century. During the first two decades, the wild Colorado River periodically flooded towns and farmland throughout the river's lower basin, devastating places like California's fertile imperial valley. What was needed, the government decided, were dams for flood control and irrigation, dams that would convert the Colorado from a natural menace to a national resource. And so in 1923, Colonel Claude Birdseye and his men were dispatched from the U.S. Geological Survey to look for possible dam sites. On the first of August, the Birdseye expedition set out from Lee's Ferry, determined to tame the Colorado River, and have a good time doing it. The legacy of the Birdseye expedition now dominates life in the Grand Canyon. Glen Canyon Dam, built in 1964 just 15 miles above Lee's Ferry, is one of 15 dams now controlling the Colorado River system. The dam has flooded what used to be Glen Canyon, storing the Colorado's waters in a massive, man-made lake stretching 280 miles to the north. The lake is named after the region's premier explorer, Lake Powell. The Glen Canyon Dam is run by the Federal Bureau of Reclamation, and until recently has been a steady producer of premium-peak hydroelectric power, available instantly during periods of high demand to the states of the southwest. Downstream, the dam has dramatically altered the Colorado River and the Grand Canyon's ecosystem, in ways that scientists are still struggling to understand.

STANLEY BEUS: One of the concerns we have now is that things are changing within the Grand Canyon along the river. The wildlife is changing. The plant life is changing. The beaches are changing. The fish populations are changing. Some of this may be good, as we look at it, and some of it may be objectionable or harmful. We don't really know all of that. But clearly, things are changing because of what we have done upstream.

LINDA HUNT: Certain changes are quite apparent, such as the erosion of beaches. Since the river's flow is now regulated, there are no springtime floods to bring in fresh sand to replenish the beaches. In addition, the dam's peak power production requires sudden release of huge volumes of water stored in Lake Powell. This creates sudden fluctuations in the river's flow, which tear away at the canyon's beaches. The river has been known to rise by 13 feet in 24 hours. Stanley Beus leads a research team that's been tracking the beach erosion since 1980. Their work is part of a major Grand Canyon environmental impact study.

STANLEY BEUS: What we hope to do with this study is provide sufficient data so that the Bureau of Reclamation can manage the flow of water through Grand Canyon in such a way as to both provide power generation as needed, and still protect the beaches from being eroded away.

LINDA HUNT: As this historical footage shows, the wild pre-dam Colorado, whose name means red in Spanish, carried a heavy load of sediment as it coursed through canyons. Now, its powerful surge is stopped at Glen Canyon Dam, and the sediment settles out, dropping to the bottom of Lake Powell. So, the Colorado River of today is clear and green. It's also far colder, 45 degrees year round, because the water released into the canyon comes from deep in Lake Powell. While trout flourish in the colder temperatures, the canyon's native fish are in trouble. Two species have been wiped out, and others, like this unusual hump-back chub, are endangered. Deer have always been seen near the river, but it's unknown how they are being affected by another major change here, a dramatic increase in vegetation. Now that the dam stops the floods that used to tear away young plant life, this new, larger corridor of greenery has taken hold. The new growth supports more insects, more reptiles, and more bird life. But what the dam has created, it may one day take away. Plants are rooted in sands, and if the beaches continue to be eroded, this new vegetation may disappear with them. The environmental impact study will ultimately take into account the conclusions of 94 scientific research projects, tracking all the changes in the canyon, great and small. In November 1991, the Secretary of the Interior made an interim decision to reduce peak flows of water at the dam by 70 percent. A final decision is expected in 1994. Back on the river at mile 77, we enter a dramatic passageway into the deepest part of the canyon. Here, we encounter the twisted and melted forms of the canyon's oldest rocks, the 1.7-billion-year-old Vishnu schist.

IVO LUCCHITTA: OK, and here we are at the beginning of the inner gorge, which is composed of these dark and rather sinister-looking rocks called the Vishnu schist. These rocks once were sandstone and shale, which have been cooked by great heat and pressure at the base of what was probably a very high mountain range once upon a time. And they are very hard as a result, and Powell knew this very well. And he was worried that perhaps there may be some pretty hairy river running ahead of him because of that.

LINDA HUNT: The Vishnu schist is all that remains of mountains that once rose as high as the Himalayas. Over the course of 800 million years, through the grinding power of erosion, these mountains were worn down to their ancient roots, which have been melted by the Earth's internal heat. Because of the extreme hardness of these rocks, the river flowing through them is tightly constrained with rough rapids.

GREGORY PECK: The gorge is black and narrow below, red and gray and flaring above, with crags on the walls. Down in these grand, gloomy depths we glide, ever listening, for the mad waters keep up their roar. The boats are entirely unmanageable.

LINDA HUNT: The next morning, at mile 157, the GSA group discovers another of the canyon's magical places, Havasu Canyon and the turquoise waters of Havasu Creek. At the falls, we join a group of young hikers already plunging in. Twenty miles farther on, we enter a dramatic landscape created by the most recent cataclysmic events in the canyon. Here stands Vulcan's Anvil, a huge block of lava which was cast out of the throat of an erupting volcano a million years ago. It stands as herald to the vast flows of lava which once cascaded over the canyon walls downstream.

GREGORY PECK: What a conflict of water and fire there must have been here! Just imagine a river of molten rock, running down into a river of melted snow. What a seething and boiling of the waters! What clouds of steam rolled into the heavens!

LINDA HUNT: No volcanoes are currently active. But the best place to see the ancient flows is from the air above Prospect Valley. The only way to get to Prospect Valley Overlook is by helicopter. The mountains in the distance are all dormant volcanoes, and nearby, the cinder cone of the canyon's own volcano.

GENE SHOEMAKER: We're standing here on the south rim of the canyon, just opposite one of the young volcanoes, which you can see behind me, which is called Vulcan's Throne. Lavas have spilled down over the rim of the canyon and all the way down into the canyon floor. These are the youngest rocks that have been formed now, in the region of the Grand Canyon. And the succession of flows that has come out has dammed the river over a period of time. And in fact, a whole series of dams were built and then cut away by the river, the highest lava dams rising more than 1,000 feet above the river floor, backing the water up all the way almost to Lee's Ferry, at one point.

LINDA HUNT: River gravels plastered high on the canyon walls show that in the past million years, lava flows blocked the river at least 13 times, flooding the canyon and creating enormous lakes. But each time, the river would eventually carve its way through.

GENE SHOEMAKER: Well, the history of the river, sweeping away each successive lava dam, bears a lesson for us, of course, with regard to the dams made by man, because surely, that will happen also with the dams that we have built on the river that we think are so permanent and so massive, such as Glen Canyon Dam. That will also be swept away, and it will be gone in a twinkling, geologically, and it will be taken away just as surely as the great dams downstream.

LINDA HUNT: Just below Vulcan's Throne roars Lava Falls, by far the largest and most feared rapids in the canyon, a dramatic drop of 37 feet. It's famous for an especially nasty hole created by a collection of underwater boulders.

GENE SHOEMAKER: Well, Lava Falls is my nemesis on the river. That's the one spot where I actually had a problem with the boat, dropped it into a hole at the head of the rapid. It didn't look like the boat was going to come out, so I decided it would be time to get out of the boat, and went through Lava Falls in my life jacket. Of course, the boat popped right out of the hole as soon as I abandoned it, and it came through, right side up. But meantime, I spent most of my time underwater. It's not a way that I recommend going through Lava Falls for anyone else.

LINDA HUNT: Now it's our turn. It only takes 13 seconds, so why does it feel like a lifetime? Nearly through—But watch that tight corner. By the time John Wesley Powell and his men reached this part of the river, their rations were down to coffee and beans. Half the men had no shoes, and there were not enough blankets to go around. Even George Bradley, who had saved Powell's life, was losing patience with the Major, as his diary records.

TIM SAWYER: Have been working like galley slaves. The Major, as usual, has chosen the worst camping ground possible. If I a dog that would lie where my bed is made tonight, I would kill it, and swear I never owned it. Impossible to keep anything dry.

GENE SHOEMAKER: The single major tragic episode of Powell's first trip occurred as a result of the separation of three men in his party, men who decided that they had had enough in the rigors of trying to push down the lower part of the Grand Canyon. They finally came to a great rapid, which just discouraged them completely. And three of the men, the Holland brothers and William Dunn, decided they would rather risk their lives hiking out of the canyon and back to the Mormon settlements on the north rim, than to try to run the rapid. Powell did his best to persuade these men to go with him and not to climb out, but he was unsuccessful.

GREGORY PECK: For me, there is no sleep. All night long, I pace up and down. And at one time, I almost conclude to leave the river. But to say that there is a part of the canyon which I cannot explore, having nearly accomplished it, is more than I am willing to acknowledge. I determine to go on.

LINDA HUNT: The next day, the three men held to their decision, and left the expedition here, at what is now called Separation Canyon. At the end of their long climb to the rim, they were mistaken for prospectors who had molested an Indian woman, and were killed on the spot by tribesmen. Unaware of their companions' fate, Powell and his remaining men continued on their journey. Two days later, the great walls leveled out, and they emerged safely from the Grand Canyon.

GREGORY PECK: The relief from danger and the joy of success are great. The river rolls by us in silent majesty. Our joy is almost ecstacy. We sit till long after midnight, talking of the Grand Canyon, talking of home.

LINDA HUNT: When Powell returned from the canyon, he became a national hero. He went on to survey the entire Southwest, and later became director of the U.S. Geological Survey. He fought to slow the rapid, unplanned settlement of the West, predicting today's bitter battles over the region's limited supplies of water. It has been said that John Wesley Powell understood the West better than anyone.

GREGORY PECK: The glories and the beauties of form, color, and sound unite in the Grand Canyon. It has infinite variety. You cannot see the Grand Canyon in one view. You have to toil from month to month through its labyrinths. If strength and courage are sufficient for the task, a concept of sublimity can be obtained, never again to be equaled on the hither side of paradise.

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TRIP MEMBER: We're almost through our journey now. We head on into camp, our bones a little weary, our clothes a little damp. Our spirits, though, are soaring, for while we're in this place, no one can try to take from us the smile that's on our face.

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