Assembling California [Paperback]

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 in the Golden State. Moores' view of California's disorganization is reinforced by the many directions faults take around the state. Garlock, Hayward, White Wolf are names that impinge on the notoriety of San Andreas. San Andreas, for all its fame, is not a fault, but a melange of fault structures, due to those impinging island arcs. McPhee's timing was fortuitous. As he was preparing the text, the earth was preparing a fitting conclusion to his story. In October of 1989 the earth moved and presented "an invoice of six billion dollars for a few moments of shaking." McPhee, like a diarist recording a life, follows the 'quake from its origins through the state. It's more compelling reading than any mystery novel. Wherever you live, you will come away from this book with an enlightened view of what the earth can tell you. And you will seek out more McPhee. [stephen a. haines - Ottawa, Canada]