Nancy L. Penrose

Nancy L. Penrose is a writer based in Seattle and worked for many years as a science writer and editor at the University of Washington. Her essays have been published in Shenandoah: The Washington and Lee Literary Review; 1966: A Journal of Creative Nonfiction; Drash: Northwest Mosaic; the collections of Travelers’ Tales; and the anthology Burning Bright: Passager Celebrates 21 Years.


Time Missing in the Grand Canyon

On a raft trip through the Grand Canyon of North America, time was absent. Yet time past was recorded in all the rock walls that rose around me. I touched 1.7-billion-year-old stone, named Vishnu, which looked like hunks of shiny black licorice carved by the Colorado River into smooth and fluted shapes. Sometimes, if I bent my head back until my neck hurt, I could spot a layer of white rock thousands of feet above me: the Kaibab, 270 million years old, its origins in an ancient ocean.

My husband, David, and I went to the Grand Canyon—one of the planet’s most perfect geological laboratories—in search of geological bliss. We are geology geeks and on this trip we were embedded within a batch of geologists gathered by Sue Tanges, a professional and a friend of a colleague of David’s. Sue has rafted the river more times than she can count and has a passion for the stories in the stone.

As part of this earth scientist herd we traveled on motorized rafts guided by Sally Gist and boatman O.C. Dale. We gorged on the rock history exposed in the canyon walls and drew upon decades of studies, clues deciphered by geologists who had come before us to map and analyze the record of time in the rocks.

T.S. Eliot wrote about time in Burnt Norton. Like you, perhaps, I have long been captured by the opening stanza though I do not claim to fully understand it:

Time present and time past
Are both perhaps present in time future,
And time future contained in time past.

Now, back home again in Seattle, after eight days rafting the length of the Grand Canyon, I’ve decided that Eliot forgot about the absence of time.


Missing Signals

Nonexistent, absent, gone: Facebook, Twitter, voicemail, email, online news. No incoming digital signal, no strength bars, no smartphone chimes in the canyon. I’m old enough—born in 1953—so that I’ve lived most of my life pre-Internet, pre-communications that routinely travel at the speed of light though fiber-optic cables. This digital-free diet felt odd but not unfamiliar

Erased: minutes and hours. If watches are meant to help us manage time, they were useless on the river. Time in the canyon was steered by Sally, who was the lead boatman. She decided when to make camp, when to break camp, when to load the boats, when to unload the boats, when to grab a handhold in rapids, when to relax through riffles, when to tie up and go for a hike, when to stop for lunch, when to eat dinner.

On the morning of the second day, David and I threw our watches in the bottom of our river bags. The white gaps on our wrists were soon sunburned and red.


River Mile = River Time

Miles on the river are like units of time.

Mile 22: Our first camp, downriver from Mile 0 at Lees Ferry, Arizona, where we had launched the boats.

Just above mile 62: The Little Colorado River, where we swam and bumped our bodies through the froth of little rapids set in turquoise waters fed by springs.

Halfway between miles 95 and 96: A hike up Hermit Creek and the delicious waterfall we stood under like it was that longed-for shower.

Just above mile 137: Deer Creek, where the edges of the stream were lush with riparian plants—I regret not knowing their names—that fragranced the hot desert air with a wet and resinous smell.

Between miles 168 and 169: We woke to bats with wings like grey chiffon, fluttering and feeding a few feet above our cots. I trusted their genius for echolocation to keep our species apart.

A bit above mile 179: Lava Falls, perhaps the most notorious rapid on the river, with a drop of thirteen feet and a difficulty rating of 8 to 10 (10 being most difficult), depending on water level, depending on how many jagged and hazardous rocks stick out of the water, how many are hidden. The boat bucked and bent and tilted as the cold waters of the Colorado crashed over us and we screamed with shock and joy. Sally brought us through so easily; all it took was her decades of river-running experience to make it seem that way.

On our flight home, from Las Vegas to Seattle, David and I opened the guidebook and ran our fingers down the maps of the river. We tried to figure out which night we had camped where, which day we had done what. It was hopeless; without the familiar temporal fences, our hours in the canyon were smeared. It had been, perhaps, the truest of vacations, where we had left the usual spaces of time unoccupied. Even the date stamps on our cameras were useless: each was set to the wrong time zone, including one left on Gulf Standard Time from a recent trip of David’s to Oman. What we knew for sure: we entered the River at Mile 0 on Friday, June 13; we left the River at Mile 277, at Pearce Landing, on Friday, June 20.


Geology Lesson

Rivers cut and rocks erode. The Colorado and its tributaries have been carving open the Grand Canyon for six million years. The canyon is young, geologically; the grinding work of waterborne cobbles, boulders, and sands is recent.

The canyon cuts through the Colorado Plateau, a geologic region that rises like a giant tree stump hugged by Utah, Colorado, Arizona, and New Mexico. For 600 million years, this chunk of continental crust—the outermost layer of the planet—has stood unusually stable, mostly missed as great tectonic forces churned around it. The Rocky Mountains were pushed up to the north and east; the crust in the Basin and Range Province was pulled apart from Oregon south to Mexico, from New Mexico west to California.

The missing tectonic activity of the Colorado Plateau means that many of the rocks of the Grand Canyon—the limestones, sandstones, and shales that formed from sediments deposited in long-gone oceans—are still lying flat. Most have not been folded or faulted or twisted or crunched. Most are neatly stacked one upon the other, like a great pile of thick and thin rock pancakes cut open by the knife of the river.

Most, but not all. At the bottom of the canyon, beneath the flat layers, are the Vishnu and its brother rocks: Rama, Brahma, and Zoroaster. These names began with Charles Dutton, a 19th-century American geologist with an interest in Eastern religions. Today’s geologists know that the contorted stories in these bottom rocks come from the eon that birthed western North America some 2 billion years ago.


Sunset, Moonrise, Rocklight, Sunrise

Absent watches, we used clues from the solar system. Sunset and the following dark meant it was time to lie down on cots set up on sand banks beside the river, time to pull up a sleeping bag against the relief of cool night air after the piercing 100-degree heat of the days.

At night, absent the sun and the light from the yet-to-rise moon, the sky was stuffed with stars. No glare from cities, no clouds, little moisture in the desert air. I always spent time before sleep lying on my back, looking up. Occasionally I caught the streak of a shooting star. Not really a star, of course, but rather the trail of light from a meteoroid—a rock from outer space—passing through Earth’s atmosphere.

On the very first night, the full moon appeared after midnight and traveled the river space between the canyon walls. The brightness sent darkness into absence, changed night into day, as if great floodlights in the cathedral of the Grand Canyon had been switched on. Within that light, which is from the rays of the sun reflecting off the moon, the rock walls shimmered.

Sunrise meant time to wake up and enter the morning routine: Swap sleepwear for pants and t-shirt, quickly, so as to pretend some kind of modesty in the middle of the open, no-tents camp. Cram stuff—shoes, dirty clothes, clean clothes, extra hat, books, toothbrush, toothpaste, hairbrush—into the rubber-coated and waterproof river bag. Straddle the bag to squeeze out the air, roll down the top, cinch the black strap tight against the rapids to come. Grab a cup of coffee, then get in line for the single toilet set up each night in camp. Eat breakfast, help load the boats, climb aboard for another day on the river.


Rock Poetry

There is poetry in the names of the rocks of the Grand Canyon. I am not the first to notice this, but now, by seeing and touching, I have absorbed their syllabic flow: Moenkopi, Kaibab, Coconino, Zoroaster, Redwall, Tapeats, Vishnu, Rama, Brahma, the travertines. All carry clues to the conditions that formed them; all are windows into the past. Let me tell you about them.

  • The travertines. These are the very youngest rocks, some forming right now: time present. They are born of minerals dissolved out of older rocks by groundwater. The minerals—mostly calcium carbonate—are deposited as new stone. There are travertine terraces, travertine dams, travertine drapes that look like mountainous piles of dripped wax from monster candles. The Little Colorado and Havasu Creek, both embroidered by travertine formations, get their turquoise hues from the way light waves bounce off mineral particles carried by water.
  • Moenkopi. A red sandstone, 240 million years old, which I remember glimpsing right at the start of the trip, at Lees Ferry near the Glen Canyon dam. I have learned that in some places this rock holds the bones of early dinosaurs, including one of the best and earliest skeletons of Arizonasaurus, a crocodile-like creature that was at the top of the food chain just before dinosaurs dominated the planet. Not that I saw any dinosaur bones, but I like knowing this about the Moenkopi.
  • Kaibab. Lying right below the Moenkopi, it is, therefore, older. Light in color, mostly white, a mix of 270-million-year-old rocks that reflect the advances and retreats of an ancient ocean across this spot on the planet: limestones, sandstones, siltstones, gypsum, and chert. You can walk around on the Kaibab at the rims of the canyon.
  • Coconino. This sandstone announces its formation 275 million years ago from dunes in an erg, a desert area filled with windblown sand. Like a monochrome abstract painting of reddish brown, the Coconino’s scalloped diagonals define the bedding angles of piles of sands cemented and compacted into stone.
  • Redwall. A gray limestone stained orange-red by iron oxides washed from the rocks above it. The Redwall holds 340-million-year-old fossils—bryozoans, brachiopods, corals, and crinoids—that rise like bas reliefs from boulders on a beach on a bend in the river where we stopped and tied up the boats. Here, just below Mile 33, the Colorado has carved open a massive cave, the Redwall Cavern. Sue showed us where to look for the fossils. I brushed my fingers over the stone discs of a fossilized crinoid stem that rose like a small white spine from the reddish rock. Crinoids are echinoderms, like sea stars and sea urchins. The stem attached the animal to the floor of a long-ago ocean.
  • Vishnu and its brothers. The very oldest rocks, first appearance at Mile 78 at the bottom of the canyon walls. Geologists call them the Basement Rocks. Some were deposited in oceans; others poured out from volcanoes. Then they were contorted and reshaped by massive heat and pressure, metamorphosed into schist. The Vishnu, the Rama, the Brahma are sometimes shot through with the dazzling pink stone of the Zoroaster Granite, which is different in origin from the schists. The Zoroaster is igneous, formed from molten rock, magma, that was once miles deep beneath the surface of the Earth, which then cooled and crystallized into stone. These schists and granites are not only the oldest in the Grand Canyon but are among the oldest in the United States: the basement of the canyon and the basement of the country.



Erosion erases the evolution of a landscape. Within the astonishing completeness of the Grand Canyon’s rock record, there is a gargantuan gap. Here’s why: although stable, the Colorado Plateau has been pushed up through the eons; water has worn it down. Missing in most places: some 1.2 billion years, 25% of Earth history. Geologists have named this massive erosional unroofing the Great Unconformity.

To get a close look at this missing history, we tied up the boats just below Mile 120 and hiked into Blacktail Canyon. We paused for photos where the stair-stepped and flat-lying layers of the Tapeats Sandstone (525 million years old) rest directly on top of the twisted and contorted Vishnu Basement (1.7 billion years old). I stood close to the rocks and spanned the Great Unconformity with the tip of my finger, as if I could absorb more than a billion years of missing earth history.

There are other missing rocks, sedimentary ones named the Grand Canyon Supergroup. This set of rocks carries messages from times when archaic tectonic plates—with names like Pangea, Rodinia, and Laurentia—roamed the surface of the planet. The motions of these plates crunched and bent and tilted the Supergroup, which are occasionally found exposed in isolated blocks. We did not see them often for they are mostly missing, but what bits remain, sandwiched here and there between the Tapeats and the Vishnu, have defied the fierce erosion of the Great Unconformity. The Supergroup rocks are a rare and precious record of tumultuous times in the geologic past.

Never missing on this trip: grand vistas of canyon walls; the prance of sun on rock face and water; the changing pitch of river voice from near-silent flowing to whisper of riffles to crash and roar of rapids. Although these sights and sounds became routine, I determined to remember to savor them within the fleeting space of our time in the canyon.



Sands are the ruins of rocks. Along the riverbanks in the canyon, the sand is reddish brown with a texture like coarse cocoa powder—a mixture, a mélange, a collage of all the canyon rocks. Except, of course, those billion-some years of stone gone missing.

The sands came home with us. I find them still in the pages of my journal, at the bottom of my daypack, in the gritty coating still stuck to the maps in the guidebook, in the mechanism of my ballpoint pen, now sticky and resistant to clicking open.

I see the sands on the banks of the Colorado as time present containing time past and time future.

Past: ground from the newest to oldest rocks.

Present: spinning in the wind and peppering my eyes; outlining the wrinkles of my sleeping bag; grating the skin on the tops of my feet where sandal straps rubbed.

Future: some of these sands will create the rocks of tomorrow; they will be deposited, buried, heated, pressed by earth forces to form sandstone. And then that stone will be ground down once again by wind and by water.

So perhaps Eliot got it right about the sand.

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