Grand Canyon National Park - A River Runs Through It

The Raging River
The easy way to reach the bottom of the canyon is to ride the force that is largely responsible for this vast wound in the face of the earth -- the Colorado River. It is easy only by comparison, for the river is a great force indeed, and many rocks rapids fill its channel as it delves ever deeper into the bowels of the earth.

Paiute Indians believed that, after the god Tavwoats had cut the canyon as a path to the joyous land beyond death, he filled the path with raging waters so that people could not flee the woes of the present world for the pleasures of the next. The Hualapai, however, who dwelt within the canyon, said that the river was the runoff from an earth-covering deluge like the one Noah knew; the canyon had begun, they said, when a hero named Packithaawi had struck deep into the earth with his knife to drain off the waters. The Havasupai, who still live in the canyon, also believed that the river was runoff from a giant flood, but they credited the river itself with cutting its own escape channel.

Until quite recently, scientists agreed with the Havasupai that the Colorado River -- red and gritty with sand stripped from western Colorado and Wyoming, Utah, and much of New Mexico and Arizona -- had cut like a rasp down into the Kaibab Plateau at the same speed that the land was being uplifted. That was the way that some of the river's gorges, including the looping canyons in Canyonlands National Park, came into being. But when scientists discovered that the Colorado has run through the Grand Canyon for only 5 to 10 million years, a problem was raised, because it was at least 65 million years ago that the Kaibab Plateau -- the southernmost step of the Grand Staircase that starts with Bryce Canyon -- began its slow, sporadic uplift. Thus, the canyon cannot have been cut solely by the erosive action of the Colorado. Many theories have been formulated to explain what really happened.

Currently popular is the theory of stream piracy that, like most of the Indian legends, also involves a great flood. This explanation supposes that, after its rise, the Kaibab Plateau separated two rivers. The one on the west drained into the Gulf of California, as the Colorado does today; the other, the ancestral Colorado, ran southeastward along the bed of today's Little Colorado, into the Rio Grande. A later uplift of land blocked the ancestral Colorado and formed a large lake. Meanwhile, the headwaters of the western river had been chewing backward through the Kaibab Plateau, as we see the Paria River doing today in Bryce Canyon. Finally, the plateau was breached and the Colorado was captured, to begin running through the canyon.

There are convincing arguments against this theory, and there are counterarguments to refine it. None of them add to or detract from the canyon's grandeur or the thrill of experiencing it from the river's perspective.

Backward in Time
The river enters Marble Gorge, the Grand Canyon's magnificent foyer, from the north, diving between straight walls of grayish-tan Kaibab Limestone. Over the next 61 miles, the Colorado slices steadily southward and downward, its descent punctuated by sudden, sharp rapids. It also cuts backward in time through layer after layer of increasingly ancient stone, to a period more than half a billion years ago, before true fish swam in the sea. And faster than the river descends, the rock layers arise on either side, for the uplifted Kaibab Plateau bulges in a great hump toward the North Rim of the Grand Canyon, and Marble Gorge slices through this hump.

At about 225 million years of age, the Kaibab Limestone is the youngest rock in the Grand Canyon's walls. It is made of the remains of countless living things that rained to the floor of a sea that covered this place before dinosaurs walked, and it contains fossils of shellfish, corals, sponges, and sharks. It blends into an older limestone layer, called the Toroweap Formation, left by the life of an earlier sea.

As the river grinds its way down through the limestone, the walls rise straight and steep on both sides, channeling the sky ever tighter above. Before long, a dividing line appears at the water's edge. Below the line the walls are white, and though they rise as steeply as before, their texture is radically different. This is the Coconino Sandstone. It has no shellfish fossils, for it was left by a world of rolling dunes, where hot winds blew. Preserved in its textures are the tracks of reptiles, always scurrying uphill. (When one of them ran down a dune, its tracks were obliterated by sliding sand.)

Only about eight miles into the gorge, where Badger Creek joins the river, the steep white walls begin giving way to rubbly slopes, and the first serious rapids occur. This is no coincidence; here, the river has cut down to deep red Hermit Shale, made of mud and clay laid down on the floodplains of sluggish freshwater streams. Through this soft rock -- colored by iron oxides, sprinkled with fossils of conifer needles, fern fronds, and giant dragonfly wings -- the river slices a broad swath. The red slopes are littered with talus and boulders where the undercut sandstone and limestone have given way, and the narrow ribbon of sky spreads ever wider above. Boulders, washed into the Colorado by Badger Creek, are the cause of the rapids; plugging the channel, they force the angry water to leap frothing over their backs. The red shale goes on for more than 16 miles, but only for half of that stretch does it form talus slopes. During the second half, the shale is interleaved with thin layers of sandstone and limestone that give it more firmness. The mixture is called the Supai Group, and here the canyon walls steepen again.