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304 pages, Hardcover
First published September 1, 1992
“The two time scales—the one human and emotional, the other geologic—are so disparate. But a sense of geologic time is the most important thing to get across to the non-geologist: the slow rate of geologic processes—centimetres per year—with huge effects if continued for enough years. A million years is a small number on the geologic time scale, while human experience is truly fleeting—all human experience, from its beginning, not just one lifetime. Only occasionally do the two time scales coincide.”
“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 time—according to present theory—parts began to assemble. An island arc here, a piece of a continent there—a Japan at a time, a New Zealand, a Madagascar—came 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.”
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.