John McPhee - Assembling California

The Founding Fish
Annals of the Former World
Irons in the Fire
The Ransom of Russian Art
Assembling California
Looking for a Ship
The Control of Nature
Rising from the Plains
Table of Contents
La Place de la Concorde Suisse
In Suspect Terrain
Basin and Range
Giving Good Weight
Coming into the Country
The Survival of the Bark Canoe
Pieces of the Frame
The Curve of Binding Energy
The Deltoid Pumpkin Seed
Encounters with the Archdruid
The Crofter and the Laird
Levels of the Game
A Roomful of Hovings
The Pine Barrens
Oranges
The Headmaster
A Sense of Where You Are

The John McPhee Reader
The Second John McPhee Reader

Y ou go down through the Ocean View district of San Francisco to the first freeway exit after Daly City, where you describe, in effect, a hairpin turn to head north past a McDonalds to a dead end in a local dump. It is called the Daly City Scavenger Company. You leave your car and walk north on a high contour some hundreds of yards through deep grasses until a path to your left takes you down a steep slope a quarter of a mile to the ocean. You double back along the water, south to Mussel Rock.

Mussel Rock is a horse. As any geologist will tell you, a horse is a displaced rock mass that has been caught between the walls of a fault. This one appeared to have got away. It seemed to have strained successfully to jump out of the continent. Or so I thought the first time I was there. It loomed in fog. Green seas slammed against it and turned white. It was not a small rock. It was like a three-story building, standing in the Pacific, with brown pelicans on the roof. You could walk out on a ledge and look up through the fog at the pelicans. When you looked around and faced inland, you saw that you were at the base of a fifty-foot cliff, its lithology shattered beyond identification. A huge crack split the cliff from top to bottom and ran on out through the ledge and under the waves. After a five-hundred-mile northwesterly drift through southern and central California, this was where the San Andreas Fault intersected the sea.

I went to Mussel Rock that foggy afternoon in 1978 with the geologist Kenneth Deffeyes. I have returned a number of times since, alone or in the company of others. With regard to the lithosphere, its a good place to sit and watch the plates move. It is a moment in geography that does your thinking for you. The San Andreas Fault, of course, is not a single strand. It is something like a wire rope, as much as half a mile wide, each strand the signature of one or many earthquakes. Mussel Rock is near the outboard edge of the zone. You cannot really say that on one side of the big crack is the North American Plate and on the other side is the Pacific Plate, but its tempting to do so. Almost automatically, you stand with one foot on each side and imagine your stride lengtheningyour right foot, say, riding backward toward Mexico, your left foot in motion toward Alaska. Theres some truth in such a picture, but the actual plate boundary is not so sharply defined. Not only is the San Andreas of varying width in its complexity of strands, it is merely the senior fault in a large family of more or less parallel faults in an over-all swath at least fifty miles wide. Some of the faults are to the west and under the ocean; more are inland. Whether the plate boundary is five miles wide or fifty miles wide or extends all the way to central Utah is a matter that geologists currently debate. Nonetheless, there is granite under the sea off Mussel Rock that is evidently from the southern Sierra Nevada, has travelled three hundred miles along the San Andreas system, and continues to move northwest. As evidence of the motion of the plates, that granite will do.

For an extremely large percentage of the history of the world, there was no California. That is, according to present theory. I dont 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 timeaccording to present theoryparts began to assemble. An island arc here, a piece of a continent therea Japan at a time, a New Zealand, a Madagascarcame 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 earthquakethe throw, the offset, the maximum amount of local displacement as one plate moved with respect to the otherwas 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 thattens of thousands of examples of what people like to singularize as the big oneand 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 Lawsonwho named the San Andreas Faultwas 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 gonethat 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 apparentat least to geologiststhat 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 structuresthe 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 disposableKleenexes 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, Its 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 theyre through.