by John McPhee
For an extremely large percentage of the history of the world, there was no California. That is, according to present theory. I don’t mean to suggest that California was underwater and has since come up. I mean to say that of the varied terranes and physiographic provinces that we now call California nothing whatever was there. The continent ended far to the east, the continental shelf as well. Where California has come to be, there was only blue sea reaching down some miles to ocean-crustal rock, which was moving, as it does, into subduction zones to be consumed. Ocean floors with an aggregate area many times the size of the present Pacific were made at spreading centers, moved around the curve of the earth, and melted in trenches before there ever was so much as a kilogram of California. Then, a piece at a time—according to present theory—parts began to assemble. An island arc here, a piece of a continent there—a Japan at a time, a New Zealand, a Madagascar—came crunching in upon the continent and have thus far adhered. Baja is about to detach. A great deal more may go with it. Some parts of California arrived head-on, and others came sliding in on transform faults, in the manner of that Sierra granite west of the San Andreas. In 1906, the jump of the great earthquake—the throw, the offset, the maximum amount of local displacement as one plate moved with respect to the other—was something like twenty feet. The dynamics that have pieced together the whole of California have consisted of tens of thousands of earthquakes as great as that—tens of thousands of examples of what people like to singularize as “the big one”—and many millions of earthquakes of lesser magnitude. In 1914, Andrew Lawson, writing the San Francisco Folio of the Geologic Atlas of the United States, wistfully said, “Most of the faults are the expression of energies that have been long spent and are not in any sense a menace. It is, moreover, barely possible that stresses in the San Andreas fault zone have been completely and permanently relieved by the fault movement of 1906.” Andrew Lawson—who named the San Andreas Fault—was a structural geologist of the first order, whose theoretical conclusions were as revered in his time as others’ are at present. For the next six decades in California, a growing population tended to imagine that the stresses were indeed gone—that the greatest of historic earthquakes (in this part of the fault) had relieved the pressure and settled the risk forever. In the nineteen-sixties, though, when the work of several scientists from various parts of the world coalesced to form the theory of plate tectonics, it became apparent—at least to geologists—that those twenty feet of 1906 were a minuscule part of a shifting global geometry. The twenty-odd lithospheric plates of which the rind of the earth consists are nearly all in continual motion; in these plate movements, earthquakes are the incremental steps. Fifty thousand major earthquakes will move something about a hundred miles. After there was nothing, earthquakes brought things from far parts of the world to fashion California.
Deffeyes and I had been working in Utah and Nevada, in the physiographic province of the Basin and Range. Now he was about to go east and home, and we wandered around San Francisco while waiting for his plane. Downtown, we walked by the Transamerica Building, with its wide base, its high sides narrowing to a point, and other buildings immensely tall and straight. Deffeyes said, “There are two earthquake-resistant structures—the pyramids and the redwoods. These guys are working both sides of the street.” The skyscrapers were new, in 1978. In an earthquake, buildings of different height would have different sway periods, he noted. They would “creak and groan, skin to skin.” The expansion joints in freeways attracted his eye. He said they might open up in an earthquake, causing roadways to fall. He called the freeways “disposable—Klee-nexes good for one blow.” He made these remarks in the shadowy space of Second Street and Stillman, under the elevated terminus of Interstate 80, the beginnings of the San Francisco Skyway, the two-level structure of the Embarcadero Freeway, and so many additional looping ramps and rights-of-way that Deffeyes referred to it all as the Spaghetti Bowl. He said it was resting on a bog that had once surrounded a tidal creek. The multiple roadways were held in the air by large steel Ts. Deffeyes said, “It’s the engineer in a game against nature. In a great earthquake, the ground will turn to gray jello. Those Ts may uproot like tomato stakes. And that will seal everyone in town. Under the landfill, the preexisting mud in the old tidal channel will liquefy. You could wiggle your feet a bit and go up to your knees.” In 1906, the shaking over the old tidal channel that is now under the freeways was second in intensity only to the San Andreas fault zone itself, seven miles away. “Los Angeles, someday, will be sealed in worse than this,” he continued. “In the critical hours after a great earthquake, they will be cut off from help, food, water. Take one piece out of each freeway and they’re through.”
In a rented pickup, we had entered California the day before, climbing the staircase of fault blocks west of Reno that had led the Donner party to the crest of the mountains named for snow. In California was the prow of the North American Plate—in these latitudes, the sliding boundary. California was also among the freshest acquisitions of the continent. So radical and contemporary were the regional tectonics that the highest and the lowest points in the contiguous United States were within eighty miles of each other in California. As nowhere else along the fortieth parallel in North America, this was where the theory of plate tectonics was announcing its agenda.
Over the years, I would crisscross the country many times, revisiting people and places, yet the first morning with Deffeyes among the rocks of California retains a certain burnish, because it exemplified not only how abrupt the transition can be as you move from one physiographic province to another but also the jurisdictional differences in the world of the geologist. As we crossed the state line under a clear sky and ascended toward Truckee, we passed big masses of competent, blocky, beautiful rocks bright in their quartzes and feldspars and peppered with shining black mica. The ebullient Deffeyes said, “Come into the Sierra and commune with the granite.”
A bend or two later, his mood extending even to the diamondshaped warnings at the side of the road, he said, “Falling-rock signs are always good news to us.”
Then a big pink-and-buff roadcut confused him. He said he thought it consisted of “young volcanics,” but preferred to let it remain “mysterious for the moment.” The moment stretched. Deffeyes is as eclectic as a geologist can become, a generalist of remarkable range, but his particular expertise—he wrote his dissertation in Nevada and has done much work there since—was fading in the distance behind him. Up the road was a metasediment in dark and narrow blocks going every which way, like jackstraws. Deffeyes got out of the pickup and put his nose on the outcrop, but he had an easier time identifying a bald eagle that watched him from an overhanging pine.
“You need a new geologist,” he said to me.
We took a rock sample, washed our hands in melting snow, and ate a couple of sandwiches as we watched wet traffic with bright headlights come down from Donner Summit. Looking back to the cloudless Basin and Range and seeing what lay ahead for us, Deffeyes said, “Out of the rain shadow, into the rain.”
After we got up into the high country ourselves, some additional metasediment left him colder than the rain. “The time has come to turn you over to Eldridge Moores,” he said.
A few miles farther on, we came to a big, gravelly roadcut that looked like an ash fall, a mudflow, glacial till, and fresh oatmeal, imperfectly blended. “I don’t know what this glop is,” he said, in final capitulation. “You need a new geologist. You need a Californian.”
Moores could be found on a one-acre farm in the Great Central Valley—in a tract surrounded on three sides by the vegetable-crop field labs of the University of California, Davis. Twenty years earlier, Davis had been an agricultural college, but it had since expanded in numerous directions to take its place beside Berkeley, attracting to the Geology Department, for example, such youthful figures of future reputation as the mantle petrologist Ian MacGregor and the paleobiologist Jere Lipps, not to mention the tectonicist Eldridge Moor
es.
At one time and another, over a span of fifteen years, Moores and I would not so much traverse California as go into it in both directions from the middle. We would hammer the outcrops of Interstate 80 from Nevada to San Francisco, reaching out to related rock even farther than Timbuctoo. Timbuctoo is in Yuba County. The better to understand California, I would follow him to analogous geological field areas in Macedonia and Cyprus—journeys much enhanced by his knowledge of modern Greek. He has read widely in Greek history as well as geologic history, and standing on the steps of the Parthenon he sounds like any other tour guide—recounting wars, explosions, orations, and stolen marbles—until he tells you where the hill itself arrived from, and when, and why the Greeks sited their temple on soluble rock that they knew to be riddled with caverns. Moores has been a counsellor through all my projects in geology, across which time our beards have turned gray. He and his wife, Judy, still live in their turn-of-the-century farmhouse, with its high ceilings, its old two-light windows, its pools of sun on cedar floors. Their children—who were five, eight, and eleven when I met them—are grown and gone. On each of two porches lie big chunks of serpentine—smooth as talc, mottled black and green. When you see rocks like that on a porch, a geologist is inside.
In the living room is a framed montage of nine covers from Geology, a magazine introduced in the nineteen-seventies by the Geological Society of America and raised during the editorship of Eldridge Moores (1981-88) to a level of world importance in the science. Moores is the sort of person who runs up flights of stairs circling elevator shafts, because elevators are so slow. He edited Geology while teaching full time and advancing his own widespread research. The montage was a gift to him from people at the G.S.A. It includes fumaroles in Iceland, dunes in southern Colorado, orange-hot lava on Kilauea, and a painting of a Triceratops being eaten alive by a Tyrannosaurus rex. In the heavens close above the struggling creatures is the Apollo Object—an asteroid, roughly six miles in diameter—that is believed to have collided with the earth and caused the extinction of the dinosaurs. In the editor’s notes on the contents page, Moores referred to the painting as “the Last Supper.” There were outraged complaints from geologists.
The centerpiece of the montage is a 1988 cover showing Moores on a coastal outcrop playing a cello. Moores grew up in Arizona’s central highlands, in a community so remote and sparse that it was called a camp. A very great distance from pavement, it was far up the switchbacks of a mountain ridge and among the open mouths of small, hard-rock mines. At the age of thirteen, he learned to play the cello, and he practiced long in the afternoons. The miners, his father included, could not understand why he would want to do that. Moores has played with symphony orchestras in Davis and Sacramento. The coastal outcrop on the cover of Geology is the brecciated limestone of Petra tou Romiou, Cyprus. Moores in the field has long since overcome the most obvious drawback of a cello. He travels with an instrument handcrafted by Ernest Nussbaum in a workshop in Maryland. Essentially, it is just like any other cello but it has no belly. Neck, pegbox, fingerboard, bridge—everything from scroll to spike fits into a slim rectangular case wired to serve as an electronic belly. This is a Sherpa’s cello, a Chomolungma cello, a base-camp viol. In Moores’ living room is a grand piano. Still on a shelf behind it are the sheet-music boxes of his children, labelled “Brian Clarinet,” “Brian Bassoon,” “Kathryn Cello,” “Geneva Piano,” and “Geneva Violin,” and three additional boxes labelled “Eldridge Cello,” “Eldridge Cello and Piano,” “Eldridge Cello Concertos and Trios.”
Judy grew up in farming country in Orange County, New York. On her California acre of the Great Valley she grows vegetables twelve months a year, and has also raised bush strawberries, grapes, blackberries, goats, pigs, chickens, pears, nectarines, plums, cherries, peaches, apricots, asparagus, ziziphus, figs, apples, persimmons, and pineapple guavas—but not so prolifically in recent years, because she has been working with a group that provides food and emergency assistance for homeless people and for people who have run out of money and are about to be evicted. She has worked in regional science centers since she was a teen-ager, and, with others, she founded one in Davis. School buses bring children there from sixty miles around to get their hands on spotting scopes, microscopes, oscilloscopes, and living snakes, on u-build-it skeletons, on take-apart anatomies and disassembled brains. Judy, trim and teacherly, puts her hands palms down on a table to show the interaction of lithospheric plates. Lithosphere, she explains in simpler words, is crustal rock and mantle rock down to a zone in the mantle that is lubricious enough to allow the plates to move. Thumbs tucked, fingers flat, the hands side by side, she presses them hard together until they buckle upward. The hands are two continents, or other landmasses, converging, colliding—making mountains. The Himalaya was made that way. Placing the hands flat again, she slowly moves them apart. These are two plates separating, one on either side of a spreading center. The Atlantic Ocean was made that way. She begins to slide one hand under the other. This is subduction. Ocean floors are consumed that way. Thumbs tucked, fingers flat, palms again side by side, she slides one hand forward, one back, the index fingers rubbing. This is the motion of a transform fault, a strike-slip fault—the San Andreas Fault. Parts of California have slid into present place that way. Convergent margins, divergent margins, transform faults: she has outlined the boundaries of the earth’s plates. There is enough complexity in tectonics to lithify the nimblest mind, but the basic model is that simple. Take your hands with you—she smiles —and you are ready for the mountains.
When I first went into the Sierra with Judy’s husband, in 1978, he had an oyster-gray Volkswagen bus with a sticker on its bumper that said “Stop Continental Drift.” I guess he thought that was funny. There were not a few geologists then who really would have stopped it in its tracks if they could have figured out a mechanism for doing so, but, since no one knew then (or knows for certain now) what drives the plates, no one knew how to stop them. Plate tectonics had arrived in geology just about when Moores did, and—in his metaphor—he hit the beach in the second wave. He has called it “the realization wave”: when geologists began to see the full dimensions and implications of the new theory, and the research possibilities it afforded—a scientific revolution literally on a global scale.
Physiographic California, for much of its length, is divided into three parts. Where Interstate 80 crosses them, from Reno to San Francisco, they make a profile that is acutely defined: the Sierra Nevada, highest mountain range in the Lower Forty-eight; the Great Central Valley, essentially at sea level and very much flatter than Iowa or Kansas; and the Coast Ranges, a marine medley, still ascending from the adjacent sea.
In this cross section, the Coast Ranges occupy forty miles, the valley fifty miles, the mountains ninety. All of it added together is not a great distance. It is not as much as New York to Boston. It is Harrisburg to Pittsburgh. In breadth and in profile, a comparable country lies between Genoa and Zurich—the Apennines, the Po Plain, the Alps.
An old VW bus is best off climbing the Sierra from the west. Often likened to a raised trapdoor, the Sierra has a long and planar western slope and—near the state line—a plunging escarpment facing east. The shape of the Sierra is also like an airfoil, or a woodshed, with its long sloping back and its sheer front. The nineteenth-century geologist Clarence King compared it to “a sea-wave”—a crested ocean roller about to break upon Nevada. The image of the trapdoor best serves the tectonics. Hinged somewhere beneath the Great Valley, and sharply faulted on its eastern face, the range began to rise only a very short geologic time ago—perhaps three million years, or four million years—and it is still rising, still active, continually at play with the Richter scale and occasionally driven by great earthquakes (Owens Valley, 1872). In geologic ages just before the uplift, volcanic andesite flows spread themselves over the terrain like butterscotch syrup over ice cream. Successive andesite flows filled in local landscapes and hardened flat upon them.
As the trapdoor rises—as this immense crustal block, the Sierra Nevada, tilts upward—the andesite flows tilt with it, and to see them now in the roadcuts of the interstate is to see the angle of the uplift.
Bear in mind how young all this is. Until the latter part of the present geologic era, there was no Sierra Nevada—no mountain range, no rain shadow, no ten-thousand-foot wall. Big rivers ran west through the space now filled by the mountains. They crossed a plain to the ocean.
Remember about mountains: what they are made of is not what made them. With the exception of volcanoes, when mountains rise, as a result of some tectonic force, they consist of what happened to be there. If bands of phyllites and folded metasediments happen to be there, up they go as part of the mountains. If serpentinized peridotites and gold-bearing gravels happen to be there, up they go as part of the mountains. If a great granite batholith happens to be there, up it goes as part of the mountains. And while everything is going up it is being eroded as well, by water and (sometimes) ice. Cirques are cut, and U-shaped valleys, ravines, minarets. Parts tumble on one another, increasing, with each confusion, the landscape’s beauty.
On the first of our numerous trips to the Sierra, Moores pulled over to the shoulder of the interstate to have a look at the outcrop that had frustrated Ken Deffeyes—the one that Deffeyes had identified as glop. It was sixteen miles west of Donner Summit, beside a bridge over the road to Yuba Gap. Moores in the field looks something like what Sigmund Freud might have looked like had Freud gone into geology. Above Moores’ round face and gray-rimmed glasses and diagnostic beard is a white, broad-brimmed, canvas fedora featuring a panama block. There are weather creases at the edges of his eyes. He typically wears plaid shirts, blue twill trousers, blue running shoes. On one hip is a notebook bag, on the other a Brunton compass in a cracked leather case. He is a chunky man with a long large chest and a short stretch between his hips and the terrain. From cords around his neck dangle two Hastings Triplets, the small and powerful lenses that geologists hold close to outcrops in order to study crystals. He did not need them to see what was incorporated in this massive paradox of glop. It contained jagged rock splinters and smoothly rounded pebbles as well. “It’s hard at first blush to tell that it’s mudflow and not wholly glacial,” Moores said. “It is mostly andesite mudflow breccia with reworked stream gravel in it and glacial till on top, which appears to be moraine but is not.”
