Annals of the Former World

by John McPhee

  To Steve Edelman, a young structural geologist and tectonicist trained at Davis and the University of South Carolina, that suggested a genuine ophiolite, however baffling its history might be, and he believed he had found the sheeted dikes that would seal the discussion. He was the one geologist who had ever come out of the Sierra mentioning this possibility. One day in 1989, Edelman got off a train in Davis (being between jobs and between grants, he could not afford to fly) and started for the mountains to enrich his field research. He asked Moores to go with him, and I went along.

  Edelman, whose beard is red, looked like a tennis player prepared to serve with a rock hammer. He was wearing a pink eyeshade in foam plastic, an aqua T-shirt, shorts, Adidas shoes, and white socks with red and blue bands. We went down a very steep canyonside more than five hundred vertical feet into the narrow defile of Slate Creek, close to the mining camps of Grass Flat, French Camp, and Yankee Hill, and closer to Devils Gate. Slate Creek was a place of spare light, where miners had removed a hundred thousand ounces of gold. In California canyons as remote as this, gold has more recently been grown in the form of plants with spiky leaves of the sort that were painted by Henri Rousseau. In a statewide effort to stop the industry, the government in Sacramento had organized something called CAMP—Campaign Against Marijuana Production. CAMP narcs were said to be posing as geologists when they roamed the wild country. A geology graduate student from the University of Texas, doing field work in the northern Coast Ranges, had been murdered, presumably by marijuana growers—shot in the back of the head. The killers have never been caught. A man in the California Division of Mines and Geology whose work frequently takes him into the Sierra foothills goes into every bar in every old mining camp and forest hamlet within a radius of five or ten miles and tells everyone present what he is doing and where. Out in the crops and outcrops, when he encounters people they know about him.

  To the nineteenth-century miners a lot of rock was slate. Slate Creek was flowing over a beautiful gray diabase. I remarked that it was one of the clearest streams I had seen anywhere south of the Brooks Range. Moores marvelled, too, saying that he could see “shear-sense indication in porphyroclasts at the bottom of the creek—it’s that clear.”

  This seemed to please Edelman, but not greatly. He had asked Moores to come to Slate Creek to see if he could agree that the diabase, as old and recrystallized and murkily deformed as it was, showed any pentimento of the laminations and chilled margins of sheeted ophiolitic dikes.

  Seeing nothing in his lens that impressed him as he moved from ledge to ledge upstream, Moores struggled to be cooperative. He said, “It’s not a good stretch. We have to get around the next bend … . I think I see some folding, some layering. Maybe it’s gabbroic.”

  Edelman seemed to speed up a bit.

  “Maybe that is a pillow there,” Moores said, hopefully. But doubt was the pillowcase.

  Now Edelman was on the run. He promised better things ahead. We had not yet reached the exposures he wanted us to see. Around the next bend, he closely scrutinized a big outcrop that jutted into the stream. He said that in his judgment it was a set of sheeted dikes. What did Moores think?

  Moores leaned in to the rock, lingered, drew back, and said, “It’s O.K. if you’re a believer. It’s not a skeptic’s outcrop.”

  “And this one?”

  “Only slightly more convincing than the last.”

  Edelman was right, though. The farther we moved upstream, the more the gray rock seemed to exhibit the features he had asked Moores to witness. But the weathering and deformation were such that the laminations were not easy to discern. Moores, with his leather cases and leather pouches lined up on his belt, his widebrimmed fedora shading his beard, appeared to have been there since 1849.

  “I don’t think a Howard Day type skeptic is going to believe this,” he said, mentioning a metamorphic petrologist at Davis.

  “No,” Edelman said. “I guess not.”

  Moores said, “Fortunately, there’s only one of those in the world.”

  Edelman said, “I know it gets good up here ahead of us. Suspend your judgment until you see the good stuff—until you see the well-defined sheeted dikes.”

  A little farther on, Moores paused at an outcrop for a long close look, with and without a lens. Minutes went by. Slate Creek went by, making the only sound. At last, Moores said, “That’s a good one. That would convince Howard Day.”

  The next ledge was even better. Moores examined it for some time. Edelman’s expression was full of sniffed victory. Moores said, “I have no doubt that that is a chilled margin. And that. And that.” Looking into Edelman’s eyes, he added, “But I’m a believer.”

  Another few yards, another rock face, and Moores said, “If you were an ophiolite and someone took you down to six hundred degrees and twenty kilometres, maybe this is what you would look like. If this is not a dike complex, what else could it have been? Nothing, is my answer.”

  Edelman said, “So. Do you believe in the Devils Gate Ophiolite?”

  Moores said, “I believe in the Devils Gate Sheeted Dike Complex.”

  Edelman: “You happy?”

  Moores: “Yes.”

  Edelman: “Another ophiolite in the Sierra.”

  A lot of geology is learned now from seismic waves and satellites, and pieced together on printout paper in artificial light. Neither a seismometer nor a satellite was ever going to see what Edelman had seen.

  Moores said, “If you took Japan and its old ocean crust and collided it with the state of Washington, and the old crust was shoved over Washington, you might have something like the Feather River peridotite. If this is an ophiolite, it is bigger than the Troodos of Cyprus. It does not appear to be a part of Sonomia. It could be a subsidiary of Smartville. You don’t know what it’s doing here. You just know it’s big and it’s important.”

  If the Feather River peridotite inconveniences the exoticterrane story, it is well that it should, he said. The old picture of the western margin of North America is gone, but not long gone. The present description of assembling terranes is so new—and calls for so much working out—that it hardly requires acid-free paper. Did a large pre-assembled terrane—the Stikine Superterrane, of which Smartville would be a part—dock in the Jurassic? Or did the United Plates of America, as they have been called, arrive separately? “Most of the ophiolites from the Brooks Range on down through central British Columbia into the western United States and in Baja California and Costa Rica are Mesozoic in age,” Moores said. “They appear to represent some sort of island-arc complex that collided with western North America in mid-Jurassic time. Singly or collectively? That’s hard to say. You can make it the one or the other. We can’t work that out now. The timing seems to be different. It seems to be lower Cretaceous in the Brooks Range, mid-Jurassic in British Columbia, mid-Jurassic in the Sierra Nevada, and somewhat younger as one goes farther south. That could be a single, ragged-edged collision. Or it could be several terranes coming in. We’re not prepared to say.”

  There remain in the world, of course, geologists who are not prepared to say that exotic terranes exist in such prodigious quantity. Homicidal in their sarcasm, they still like to assert that their less conservative colleagues are prone to name new terranes for any change of lithology, at any formation boundary—in fact, at any place, however small, where it is easier to claim that something is exotic than to figure out the relationships of present and missing parts. In the geology of such people, it is said, a microterrane is a field area. A nanoterrane is an outcrop. A picoterrane is a hand specimen. A femtoterrane is a thin section.

  Although the outer shell of two-thirds of the earth is rock of the ocean crust, it is so inaccessible to the field geologist that to study even the fragments that have broken off on continental margins requires prodigious travel. Moores has pursued his specialty from Oman to Yap to Tierra del Fuego to Pakistan, and routinely has returned to the eastern Mediterranean—most of all to Cyprus. One autumn in
the nineteen-eighties, when I was working in Switzerland, I flew to Cyprus to watch him do his geology there.

  He met me at Larnaca, we drove north, and within the hour were tectonically deconstructing a huge broiled fish and drinking dark Cypriot wine. Politically, Cyprus was in Asia, Moores said, but geologically it belonged to no continent. It rested on the lip of Africa but was not African. It was not Eurasian. In the lowercase and literal sense, it was mediterranean. Long after the last supercontinent began rifting and its new internal shorelines bordered the Tethys Ocean, what was to become the foundation rock of Cyprus welled up as magma in a Tethyan spreading center. At that time, about ninety million years before the present, the Eurasian and the African sides of Tethys were twice as far apart as they are now. They continued to separate for another ten million years, and then plate motions changed. As the North Atlantic began to open, Africa began to move northeast, closing with Eurasia, as it continues to do. Ongoing results include the Alps, the Carpathians, the Caucasus, the Zagros—in Moores’ words, “a big slug of deformation that’s throwing up mountains everywhere.” By late Miocene time, geologically near the present, not much remained of Tethys in that part of the world except the Mediterranean Sea, the Black Sea, and the southern Caspian Sea.

  It was in the late Miocene that Africa levered the Tethyan floor, and broke off Cyprus. The ophiolite was thickly covered with chalk, which had settled upon the pillow lavas as a clean lime ooze, unadulterated with sediment from any landmass—as clear an indication as you could ever hope to find that Cyprus was a piece of remote deep ocean.

  For seeing and touching ocean crust—for leaning against it with a hand lens, for removing small cores to study their remanent magnetism, for mapping the varying rocks from zone to zone—there was no example in the world as well preserved as Cyprus. Shaped like a razor clam, the island had a long foot that reached up in the general direction of Turkey, which was fifty miles away. This northeastern extremity was a long low range of mountains, whose geologic history was not well understood: it seemed to be in some sense accretionary, perhaps a collection of island fragments from a confused Eurasian sea, and thus to belong—in a tectonic sense—to Turkey, which seized it by force in 1974, and established it as the Turkish Federated State of Cyprus. The Turkish Federated State of Cyprus had so far been recognized only by geologists. The thick body of the island, which rose higher than the White Mountains of New Hampshire, was the ophiolite—the exposed and integral lithospheric crust that was without continental affiliation and was the heart and substance of the independent Republic of Cyprus.

  Each day, we drove out of Nicosia down the great treeless plain of the Mesaoria, on our way to the high Troodos. Trending east-west, the plain divided the island’s most prominent lithologies. Off to our right about ten miles was the low silhouette of the north-coastal range, and ahead to the left were the Troodos. Through the Mesaoria ran a boundary drawn by the United Nations which was known among Greek Cypriots as the Green Line. Turks called it the Attila Line. Along it, over the plain, ran United Nations sentry boxes, like populated fence posts, farther than the eye could see. All north-south roads, even unpaved ruts, were barricaded and marked with warnings and instructive signs:“HALT!”

  The feel of day in the Mesaoria was like crouching too close to a campfire. Up in the Troodos were groves of shade. Under Aleppo pines, the air was as cool as deep water, and about as still. There were whole ridgelines of sheeted diabase, weathered out in silver blades—like thousands of playing cards in one standing deck—recording in subcenturies the spreading of ten million years. There were cliffs of chalk, and bulging extrusions of pillow basalt. There were layered cumulates in massive black gabbro. There were serpentine peaks. The highest peak was Mt. Olympus. In the Hellenic world are enough Mt. Olympuses to suggest tract housing for redundant gods. It is a godly talent that geologists have: not only to see ocean lithosphere in mountain crests but to feel comfortable in the knowledge that some of the lowest rock in the ophiolitic sequence is the highest rock of a place like Cyprus—with nothing overturned. A sawyer would also understand this—and almost anyone who could look at woodwork and see the original trees. The Cyprus ophiolite—great slab of the ocean—was bent upon the slope of Africa. It was draped, hung, arched, folded—not quite like Dali’s watches, but the image would do. Water entering peridotite to make serpentine had swelled the whole affair, and then erosion had taken over, finding the serpentine within the crown of the arch and variously stripping the other stuff off the top and down the sides until the serpentine stood highest and the ophiolitic sequence (reading upward) went down the mountains in successive steps, ending in peripheral cliffs of chalk. In some of the higher country, Moores chipped away at interbanded cumulates (so-called magmatic sediments) from the deepest pools of gabbro, and among them found a trace current, which he described as “a stream channel in the magma chamber.” Rapping it with his hammer, he said, “Shows you which way is up.”

  Among stone cabins whose metal roofs were weighted with stone, we hammered stone. We moved among ripening apples, Lombardy poplars, and red-roofed white villages spread on the dry mountains. We went into deep canyons. A good deal less of the massif was under forest than under grapes. From the high ridges with comprehensive views, the mountains looked like coalesced football stadiums, vineyards terraced into the sky. Above Palekhori, we picked and ate fourteen grapes, doubling the annual number destined for fresh consumption. At a table under a tree in Palekhori, we drank coffee that was good enough to eat. It was brewed in a briki scarcely larger than a gill. It came with a glass of cool water. “Palekhori” means old village. It is in the sheeted diabase, whose stately laminations are so distinct that you can all but see their lateral motion. Moores and Vine had found their best evidence of seafloor spreading at these altitudes. More recently, Moores had been studying fault blocks in the Troodos. In various tiltings of the sheeted diabase, he had seen that the rift valleys of ocean spreading centers tend to break into blocks as they widen—a version, on a small scale, of the faulting characteristic of the Connecticut Valley, for example, or the Newark Basin, or the Culpeper Basin, or the great western province of the Basin and Range.

  The mid-ocean ridges run around the world very much like the stitching on a baseball, not in simple lines but in oscillating offset segments. Such a pattern evidently accommodates a sphere. In any case, it is what the earth looks like where it is pulling itself apart. The ocean ridges of the world jump from rift valley to transform fault to rift valley to transform fault, everywhere they go. The rift valleys are typically about forty miles long, and are offset, also about forty miles, by the transform faults. Moores had found this pattern in the high Troodos. In rock beside a road, he pointed out sandstone sediments that fell into a bathymetric depression where a transform fault intersected a spreading center. A goatherd walked by—blue shirt, soft olive hat, a stick bag on his back. “Yasas!” he said, in greeting, above a din of goats. Nothing in his face suggested that he found it at all strange to come upon two men with the beards of Greek Orthodox priests squinting into coarse rock with the lenses of jewellers.

  In a remote mountain valley, we walked into a box canyon and saw feeder dikes five metres wide that had driven upward through pillow lavas to break into the ocean and form more pillow lavas. Moores and Vine were working there in 1968 when a Cypriot dressed in a business suit materialized before them. He said that he was just out for a drive and had seen their vehicle, and he asked what they were doing. He also said that he was Minister of the Interior. They told him that they were drilling into the rock to remove small cylindrical cores for paleomagnetic data, and in the course of conversation they also told him that their work was in part supported by the National Science Foundation, in Washington, D.C. The minister said, amiably, “Do you mean to tell me that your government pays you to come over here and drill holes in my island?” He stayed long enough to learn that his island was the keystone of the sea. A year and a half later, he was assassinated.<
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  In the way that the Smartville arc seems to have brought gold to California, Cyprus brought copper to the world. “Cyprus” means copper. Whether the island is named for the metal or the metal for the island is an etymology lost in time. The mining geologist George Constantinou, director of the Cyprus Geological Survey, took us south from Nicosia one morning into the hill country near a village called Sha. On soil eroded from pillow basalt, he led the way into a grove of pines that surrounded a pit forty feet deep. Like countless old mines, it was partly filled with water. He said that the pit had been there four thousand years. Constantinou was a handsome man of alternately bright and brooding aspect, with light wavy hair, strong features, and such commanding stage presence that I imagined him as an actor. I imagined him as Prince Hamlet, King Henry V, and Archie Rice, because his physical resemblance to Laurence Olivier was so close it was unnerving. Of this small excavation framed by Aleppo pines he spoke with resonance as well as reverence. Cypriots thirty-five centuries before Christ had walked into this pine grove, and others like it, and had found native metallic copper lying on the surface, he said. Pine resins in the groundwater had mixed with copper sulphate and reduced the copper to metal.

  When Cyprus was spreading in the Tethyan floor, seawater descended through fissures and—close to or within the magma—picked up quantities of dissolved copper, and lesser amounts of mercury, manganese, tin, silver, and gold. Like the black smokers active now in the Red Sea and the Gulf of California, hot brine plumes rose through the Cypriot rock and precipitated metals and metallic compounds on the pillow lavas. From everywhere in the ancient world, people turned to Cyprus for weapons-grade copper. The swords, spears, and shields of innumerable armies were made from Cypriot copper. Before long, though, the resin-reduced metals were gone. More than a millennium passed before the Cypriots learned that dark earths where the metals had been were not a whole lot less cuprous than the metal itself. Rainwater—rare in Cyprus on the human scale but continual in geologic time—had removed lighter materials and had concentrated the copper minerals malachite and azurite in an upper zone of extreme high assay. Geologists of the twentieth century would describe such a concentration as a supergene enrichment. The ancients somehow discovered that if they mixed the cuprous earth with umber, and then heated the mixture, molten copper would flow. There was plenty of umber close at hand. Umber is an oxide of manganese and iron. In spreading environments on ocean floors today, umber is piling up on the pillow lava in large dark-chocolate cones beside the black smokers, as it did on the pillows of the nascent Cyprus.