This Overpass on SR 14 Collapsed in Both 1971 and 1994
Assembling California is the fourth volume of John McPhee’s geology tetralogy, the other volumes of which are Basin and Range, In Suspect Terrain, and Rising from the Plains. I delayed finishing the quartet because, as a California resident, I relished the enjoyment I would get from reading Assembling California. My only disappointment is that, being an Easterner, McPhee was mostly enthralled by Northern California, especially the area around I-80. Oh, well, it happens.
Assembling California is all about a fact that the geology, in its own way, replicates how the people of California came together from everywhere. So, too, did the pieces of rock that form the state migrate from all over the world and stick together—a process which will continue over millions of years to take the start apart just as it put it all together. Geologist Eldridge Moores writes:
People look upon the natural world as if all motions of the past had set the stage for us and were now frozen. They look out at a scene like this and think, It was all made for us—even if the San Andreas Fault is at their feet. To imagine that turmoil is in the past and somehow we are now in a more stable time seems to be a psychological need. Leonardo Seebler, of Lamont-Doherty, referred to it as the principle of least astonishment. As we have seen this fall, the time we’re in is just as active as the past. The time between events is long only with respect to a human lifetime.
I, for one, have been through two major quakes—the Sylmar Quake of 1971 and the North Hills Quake of 1994.
There are times when I stop and listen, waiting for the earth to rise up again and send me into paroxysms of terror. Whether I live or die will depend if “I am in the right place at the right time.” I can pretend that I will never experience another earthquake, but the chances are good that I will.
The Volcano Sabancaya: Erupting Again
The Pacific Ring of Fire stretches from Indonesia and the Southwest Pacific in a massive arc around Asia, North America, down to the West Coast of South America. According to Peru This Week, this zone “is the site of 85% of global seismic activity caused by friction between shifting tectonic plates.”
In South America, the culprit is the Nazca Plate, which borders the Pacific side of the continent, and which features a convergent boundary subduction zone and the South American Plate, which action has formed the Andes. Hardly a day passes by when I don’t hear of another earthquake in Peru (usually in the Richter 4.0-5.5 range); and hardly a month passes by without a new volcanic eruption. Today, it is reported that Sabancaya (see above) in the State of Arequipa has begun to spew ash. If it continues, I will probably be there to see it in person next month at this time.
Below is an illustration of how the Nazca Plate (in light brown) subducts the South America Plate (in green), thereby causing all these dire events (and, by the way, over the millennia, causing much of the beauty of the Andes as well):
The Nazca Plate Takes a Dive, Wrinkling the Face of the Earth
Last year, I visited Iceland, through which runs the boundary between the Eurasian Plate and the North American Plate, resulting in several dozen active volcanoes and frequent earthquakes. In fact, the boundary runs right through the middle of Thingvellir National Park, where it is expanding the size of Iceland (and the park) year by year.
What is it with me and volcanoes? Is it because I live in multiply cross-faulted Southern California with its own history of earthquakes? Maybe in future I should visit Krakatoa and Mount Vesuvius?
Zion National Park
Geology is one of those subjects I would like to know much more about. Although I took the subject in college during late Ordovician times, it was all dictated by synclines, geosynclines, and anticlines, which I never quite understood—nor did the geologists who promulgated the notion.
Living as I do in the American Southwest, where the rocks are not covered by all that dirt, geology is something that seems more immediate. All the more so when the earth shakes as the tectonic plates are slowly marching on their pre-ordained paths to their next destination.
Geology is the history of what lies under our feet. It’s not just the study of rocks—though I can see where that could be interesting—but the study of long, slow processes that are changing the face of the earth. I saw some of those processes in action at Vatnajökull Glacier in Iceland, which has retreated hundreds of meters since the 1930s, when a road around the whole of the country was a laughable ides. Even now, the road across the black sands drained by the glacier is only a temporary expedient.
But then we are all temporary. If we want to see how small we are, we could make a study of the stars. But why go that far? The earth under our feet can be just as bizarre and alien. We talk about global warming as if it had never occurred before. It is just as likely that the currents of the oceans will reverse, bringing cold weather southward; and the glaciers may just start to re-form. We just don’t know.
I just finished reading John McPhee’s book In Suspect Terrain, about the forces that formed the eastern part of the United States, mostly the Appalachian Mountains. Plate tectonics explains some things, but as one geologist remarked, “While geologists argue, the rocks just sit there. And sometimes they seem to smile.”
This and the other titles in McPhee’s geological tetralogy, are good books to read if you want to puncture a few misconceptions.