American Scientist

Earth: An Intimate History. Richard Fortey. xii + 429 pp. Alfred A. Knopf, 2004. $30.

Richard Fortey's new magnum (dare I say magma?) opus, Earth: An Intimate History, is a hefty volume encased in a dust jacket with a metallic tint somewhere between copper and bronze. From a distance the book resembles one of those marvelous rocks that Fortey so enthusiastically smothers with attention in the text. The center of the front cover has a small circular cutout (obviously iconic for the spherical Earth), which serves as a window onto an old lithograph that shows Mount Vesuvius erupting (one of several striking images on the front of the binding). The effect is arresting and beautiful (hats off to designer Peter Mendelsund), a perfect complement to Fortey's stated purpose of enlightening readers about plate tectonics by showing "how the lie of the land responds to a deeper beat."

Every rock, whether copper-veined, silver-clad, black-glazed or imbued with olivine green, tells a story about the Earth as a whole. This connection was made first by Charles Lyell in the 1830s and later by his successors, who used what they learned from visits to Vesuvius, the Alps and other magnificent terrains to fashion a theory of the Earth. Of course, as Fortey describes, these early connections made between rock, region and Earth process were later transformed and fortified, becoming the modern theory we call plate tectonics.

Like the complex crust of Earth itself, Fortey's book is a mosaic—part history, part travelogue and part geological survey—which moves us with him around the globe and into Earth's interior. Fortey describes the "Temple" of Serapis near the Bay of Naples, where Lyell in 1830 challenged a static concept of the Earth with a simple observation: He noted that the borings in the midsection of the marble columns there were apparently caused by rock-eating marine clams, indicating the rise and fall of the sea and the ups and downs of a dynamic crust over vast stretches of time. Fortey calls Serapis a geological "holy place for rationalists," recognizing the oxymoron: The scarred columns evoke a rational explanation that defies many a religious conviction about the biblical brevity of Earth's history.

Fortey continues his pilgrimage to other "holy places"—the shield volcanoes of the big island of Hawaii; the spectacular overturned strata, or nappes, in the Sernft Valley of the eastern Alps; the ancient schists of Newfoundland and, of all places, Central Park in New York City; the Ellora temples (literally a holy place) within the Deccan lava deposits in India; the San Andreas Fault; the Grand Canyon; and the laboratories of Bristol University, where conditions in the Earth's interior are quite credibly reproduced experimentally.

Not content with these wanderings, the author in his last chapter takes us on a wobbly orbit around the planet to witness from afar some of the great plate features at the proper scale. Along the way, he lands at various spots to reminisce about his searches for trilobites and other fossils. These excursions reminded me that a widely published survey showed that geologists were among the most satisfied professionals. Who wouldn't be, with so much of the world as your oyster?

Geology was revolutionized by plate tectonics—an enviable change (scientists in many other fields would like to see their disciplines similarly transformed). Yet this grand unified theory of Earth processes is now rather well established—nay, aged. Fortey worries that "it is difficult to record the growth in comprehension of the earth in the light of plate tectonics without occasionally sounding smug. 'Aren't we the clever ones?' we seem to imply."

Indeed, our enthusiasm to embrace these explanations can tempt us to trivialize a great void in understanding: Although the effects of plate tectonics on mountain building, island emergence, trenching and faulting are manifest, the basic mechanisms literally underlying plate shuffling are still only partly understood. Fortey asks the yet unanswered questions: What is the energy source for the Earth's magnetic field? Does the mantle contain two sets of convection cells of fluid rock or only one? The inner workings of our home planet, the processes that determine the architecture of the deep mantle and the core, are less observable to us than the atmospheric fluctuations of a distant star. Unlike travel into deep space, a journey to the center of the Earth seems all but impossible. The closest we may get are those high-pressure, high-temperature chambers at Bristol or other research labs.

Not that a dissection of the crust itself is always that easy. Fortey beckons us to the epicenter of tortuous stratification, the Alps. The place is utterly complex, and so is the narrative, full of folding, tilting and overturning. There are also collisions: those between plates and those between ideas and personalities—the likes of Arnold Escher and Albert Heim, and their antagonist, the ultimately triumphant Marcel Bertrand. Our scrambles in the Alps eventually, albeit circuitously, lead us southward to Italy, to a fault (the Insubric Line) and a modern conclusion: that all this complexity is the result of a great plate collision. Africa, or more properly the splintered-off Adriatic plate, has been pushing against "obdurate Europe" for tens of millions of years. The upper part of the Matterhorn is actually "a part of 'Africa' thrust bodily northwards over Europe."

On this meandering journey we sometimes lose the connection between rocky visages and the bigger picture. Yet there are also crystalline explanations. We explore Via Mala—a slitlike defile so narrow that only one traveler at a time could trace its gloomy medieval footpath. Fortey tells us that the uniform character of the limy schists that form the canyon walls ensured this oppressive narrowness. "It is as if the river acted in the manner of a circular saw cutting into a particularly dense log of teak," he says. "The gorge maintained its vertiginous integrity as the mountains were delivered into the jaws of erosion."

In the Alps we also encounter Eduard Suess (1831-1914), clearly one of the giants of geology. Suess moved beyond Lyell to embrace the complexity of regions like the Alps as part of a bigger pattern of crustal upheaval. We then follow Suess to the Great Karroo in South Africa, and we are startled by his prescient observations. The similarity of ancient rocks and their fossils in Africa to those in South America and peninsular India suggested to him that these continents and subcontinents were once unified, forming a land Suess called Gondwana. Fortey is clear about the impact of this insight: "It was the acceptance of the existence of this vanished land that set the seal on modern geology." Of course, Suess is in good company, sharing the credit with such successors as Alfred Wegener, Alex du Toit and, much later, Arthur Holmes, whose rough sketch of continental drift and seafloor spreading, published in 1931, may be the most important illustration in the history of geology.

Fortey moves us to the churning present, ticking off breakthroughs allowed by new technologies for dating rocks, measuring magnetism, drilling the crust and mapping the seafloor. Casting his net broadly here to reach a diverse readership, he presents an extraordinary compilation of evidence, tests designed to find holes in plate-tectonic theory that in the end only reconfirmed the concept. Students taking a basic college course in geology should put down their textbooks for a moment and read Fortey's riveting account for clarity and inspiration.

Fortey's mid-route summary of plate-tectonic theory is a high point of the book, but what remains is anything but anticlimactic. For example, a chapter that delightfully blends history, commerce, precious minerals and plate tectonics informs us that the word dollar comes from the Dutch word daler, a variant of thaler, the one-ounce silver coin used widely in 16th-century Europe. The silver to make thalers was churned out at the great mine at Joachimsthal (now Jachymov, in what is now the Czech Republic). Why was this eastern European realm so providentially enriched? The mines are on one end of an ancient range—the Hercynian, or Variscan, fold belt, which extended through the midsection of continental Europe, terminating in the western tip of England, where mines produce more tin, lead and zinc and less silver. The range itself is, of course, the product of an earlier plate impingement, one that long preceded the rise of the Alps—the subduction of the Rheic Ocean, which once divided what is now Europe.

If Fortey's narrative has a fault, it's that it left me wanting more. I was fascinated by Doris Reynolds and her valiant battles with her many chauvinistic male colleagues in the great Granite Controversy of the 1930s, '40s and '50s. Thus I was surprised that Fortey, in his discussion of the San Andreas Fault, failed to mention the pivotal work of another extremely important woman geologist, the still very active Tanya Atwater, who explained the fault as an expression of the immense, laterally sliding boundary between the Pacific and the North American Plates. I wanted to know more about meteorites and the clues to the deeper layers of our own planet offered by the bits that they carry from the core of shattered planetoids.

Despite these wants, there is much that glitters within this copper-clad volume. Fortey tells a story of the Earth that is scientific, poetic (he quotes Seamus Heaney and D. H. Lawrence) and certainly passionate. The book is a fitting tribute to our restless home.