Reading The Grand Canyon Rocks
I've toured the world and have lived in places that most people think of only as exotic locations for documentaries. However, nothing has taken my breath away or filled my imagination more than a big ditch in the dust. The Grand Canyon.
You simply don't take the Grand Canyon lightly. The magnificent chasm is much more than a very big gash in our thin-skinned planet. To a geologist it is literally time unearthed, a ridiculously huge sweep of time that reaches all the way back to an unrecognizable Earth.
Of course everyone can appreciate the spectacle of the canyon. Listen to Clarence Dutton in his 1882 monograph on The Tertiary History of the Grand Canyon District, in which he beholds a canyon "sculptured into strange and even startling forms, and lit up with colors so rich and glowing that they awaken enthusiasm in the most apathetic."
When it came to giving names to the buttes and side canyons, Dutton chose the religious, like Vishnu's Temple, The Cloisters and The Transept. But, as Wallace Stegner wrote in Beyond the Hundredth Meridian, when it came time to explain it all, "Dutton found no gods or thunder spirits in the canyon, but only itself, self-created, protean, and immortal."
Dutton wasn't the first to let the rocks, not our holy texts, speak for the history of the planet. Beginning with James Hutton's 1788 Theory of the Earth, certain geologists slowly gathered evidence that the lay of the land could be best understood not by invoking Noah's flood, but instead by observing the continuous action of the geologic powers we see today, from the tedious accumulation of silt, to the sudden hot blurt of magma, to the incessant spill of rain. "What more can we require?" asked Hutton. "Nothing but time."
Unfortunately for Hutton, the orthodoxy held that the Earth was less than 6,000 years old... scarcely predating the pyramids. Hutton's notion of essentially infinite time was, to the church, heresy. As was Charles Lyell's 1830 Principles of Geology. As was Charles Darwin's 1859 Origin of Species. By the time geologist John Wesley Powell survived the first boat expedition through the Grand Canyon in 1869, the church still took the phrase "millions of years" as fighting words.
But it was awfully hard to argue with the Grand Canyon. Powell and Dutton, and most every geologist to follow, unhesitatingly saw in the canyon the imprint of far more than 6,000 years: They saw it in the immense beds of sediments turned to rock that form cliff and terrace; in the petrified vestiges of never-seen creatures; in the monstrous erosional gap between the canyon rims.
All that naked rock: it can change the way you see things. Or not. I'm no geologist, and I freely admit to tripping about the Grand Canyon with my mind fixed mainly on the age of my aching knees, not eons past. But a real geologist, a passionate stratigrapher or a heartfelt sedimentologist, is easily transported to vanished lands and times by a walk in the canyon, much as the "golden oldies" radio station swiftly punts me back to high school.
Just look at a cliff of Shinumo Quartzite which was once an island that was ultimately buried under an advancing sea... or the Tapeats Sandstone which is the beach that eventually covered it all... or simply ask how old is the quartzite? And the answer is about a billion years.
Most people can no better imagine a billion years than a car capable of a billion miles per hour. Rocks are dated by the slow tick of radioactive decay, and if I believe in the reality of atom bombs, I can't reject the same science when it comes up with billion-year-old rocks.
The numbers just keep on rising. Just consider the even more ludicrous figure of 1.7 billion years for the Vishnu Schist, a black mangle of rock, nicely polished and cusped by the river. And then there are the travertine dams and falls in the side canyons of Havasu and the Little Colorado, rock like cake icing that is taking shape this very minute, while the big river and the cloudbursts gnaw at the canyon, making it grander for future tourists, until the same forces that made the canyon flatten it, every stone tower and palisade collapsing, limestone and sandstone and mudstone pulverized and carried off to settle in the sea, starting the whole process anew.
At least that's what the rocks say, and to my ears it's good news. The Earth is not yet finished.