Assembling California (Annals of the Former World, 4)

With a precision of language and detail, John McPhee brilliantly evokes the terrain of earthquakes, desert, mountains, and coastline of California. McPhee's guide through the geological history and present-day is Eldridge Moores, a geological professor at UC/Davis who knows the land of California perhaps better than anyone and who can "see through the topography and see how the rocks lie in three dimensions beneath the topography." McPhee is Moores' interpreter, a writer for whom descriptions and metaphor comes as easily as geology does for Moores. Together, they take the reader through the diversity of land formations to form a complex understanding of all the forces that have been at work on this strip of land forming much of the west coast of the United States. For those only marginally interested in geology and topography, this is a difficult read, though it is well worth sticking with it. I myself read it in chunks, only a single chapter at a time, since any more tested my patience. The writing is superb, however, and the information imparted is both instructional and fascinating. When McPhee writes seemingly simple sentences such as, "There were orchards of carobs, figs, and pistachios, and an understory of prickly pears," he paints an entire countryside in just a few strokes of language. What he does with the drier subject matter of basalt and limestone is extraordinary.

If anyone tells you "science destroys beauty," respond by handing them a McPhee. Any of his works will suffice, but this one is a special treasure. It's the completion of a continent-wide tour across the United State. McPhee escorts a succession of geologists who have explained to him why the theory of continental drift requires revision. The modifiers are local geological conditions, each region telling its own tale of lithic activity. In California, the story becomes almost bizarre. John McPhee might well be considered the only writer of science who could present the story in understandable fashion. Perhaps, but he would counter that in Eldridge Moores, he enjoyed a tutor of exceptional value to guide him.The idea of plate tectonics was a revolution in viewing the earth. Previous thinking was nearly all limited to regional, often arcane, activity. Plate tectonics was the first truly global image of the planet's workings. It was elegant, universal, and it explained so much, so well, that fitting it to conditions was almost simple. Plates move, crunch one another, raise mountains, often with spewing volcanoes, and end their career by sinking below the crust. Look at a map of California [easy to do, since there's one at the front of the book]. It all seems so manifestly organized. Parallel mountain ranges running north-south, separated by logically placed valleys. But the Sierra Nevada stands in lofty majesty compared to the Coast Range standing west across the Great Valley. It shouldn't.According to Moores, that's symptomatic. By plate tectonics' definition, it should be the Coast Range that should rising in reaction to the pressure of the continental movement. And why is the Great Valley so wide if a whole continent is trying to crowd the Sierra Nevada west? Moores suggests that it's because the real western boundary of the North American Plate is around Salt Lake City. The Mormon capital as a Monterey or Santa Barbara requires some reflective thinking, but Moores knows how to read the rocks. And McPhee knows how to tell us what he sees.What Moores sees could be compared to a geologic highway accident where a string of vehicles reduce order to chaos. Plate tectonics is too simple because it fails to take into account wandering island chains. These are micro-continents with a wanderlust. Moores sees the likelihood of three island chains pranging the West Coast at different times. Each time, instead of being pushed aside by the mass of the North American Plate, they simply attached themselves like limpets. The extra pressure and mass pushed up the High Sierras and the Coast Range. Positioning, erosion and subsidence left the Great Valley, one of the flattest places in the United States, but rich with alluvial soil. The soil produces the world's best wine grapes, and McPhee and Moores justifiably pause in the Sonoma Valley.McPhee moves from Moores' analysis of mountain building to the study of earthquakes and fault lines

My firsthand experience of living in Northern California has endeared me to its fascinating geology, for not too many places on earth have seen so much upheaval: from transform faults to terranes banging against the continent, the uplift of melange complexes from the seafloor, and the splendid manifestation of batholiths that is the Sierra Nevada. A drive from Tahoe to San Francisco takes you across ancient batholiths to the fore-arc basin of the Central Valley and ultimately to the melange and suspect terrane mosaic that is the Coast Ranges, Twin Peaks, and the Marin Headlands.What John McPhee's book successfully delivers is an accessible cross-section of the geology of the golden state at your fingertips, including those, including myself, who wax nostalgic about being a former inhabitant of this geologic wonderland. McPhee explains not only geologic processes but also how geology affected exploration and exploitation of the state's resources. The geology is not dead, for it resonates to this day and to the far future, what with the awesome power yet to be unleashed from California's labyrinthine faults and from the still burgeoning mass of the Cascade volcanoes to the north. Nevertheless, McPhee gives a personal and friendly touch to California's big-time geology.

California's diverse geomorphology and geology are maddeningly complex, the results of a variety of processes occurring over some hundreds of millions of years. John McPhee does not succeed in rendering these processes "simple," but he does a fine, literate, and remarkably lucid job of explaining some of the basics as no previous author has been able to do. Most significantly, McPhee is one of the first writers to apply recent developments in the field of plate tectonics to California's geological story. Most exciting, perhaps, is his discussion of the ways in which California itself has been "assembled" from various pieces and processes, all of these the results of the various ways that tectonic plate boundaries can interact. The immense granitic batholith that forms the backbone of the mighty Sierra Nevada, for example, is the result of the Mesozoic melting and recrystalization (as granodiorite)of the now-defunct Farallon Plate as it slid beneath the neighboring North American plate to the east. The currently existing Sierra range itself has been raised to its present height only recently (mostly within the past three million years) through faulting associated with crustal stretching that apparently extends clear across the Great Basin. Perhaps even more interestingly, the Sierra foothills and several other portions of the state exhibit peculiar rock types and geology as a result of their actually having been shoved and glommed onto the continent in bits and pieces, the result of ancient plate movements that brought "exotic terrances" to the present location of California from great distances away. More recently (and geological terms, thirty million years is indeed "recent"), the tectonic plate boundary along the length of California has changed from one characterized by subduction to one in which the Pacific Plate is now sliding slowly northwestward past the North American Plate. The principal boundary between these plates is the San Andreas Fault--hence, the major effect of this particular form of plate collision is the frequent earthquakes with which Californians have become so terribly familiar.The story of how these ever-changing plate interactions have "assembled" California is a fascinating one, and McPhee tells it well. Along the way, he provides more than just geological information. He also includes historical insights into the California Gold Rush (while also explaining in geological terms where the gold originally came from), and provides colorful descriptions of California's history of great earthquakes. Although McPhee tries his best to make the complex geology of ophiolite sequences, etc., comprehensible to the non-geologist, there's very likely some frustrating reading here for people with no previous background in the intricacies of plate tectonics. Also, the lack of adequate maps and diagrams is a handicap. Were such illustrations provided, some of the plate relationships and his

As a professional geologist, I am continually amazed at the level of proficiency of John McPhee in bringing the subject to life. His ability to mesh the confusing world of structural geology, geologic vs. human time frames, and add to them a good dose of human nature and world culture continues to baffle me. After 4 years of undergraduate geology and 2 years of graduate geology, I finally understand what an ophiolite sequence is and what it means. The man redefines the meaning of the phrase "diverse writer". Tying in the discussion of structural geology and historical geology to the last chapter "the Loma Prieta Earthquake" was fantastic. Fortuneately my copy of Coming Into the Country just arrived, so I am off again...