A Crack in the Edge of the World Read Free

one of those Old Geologists—the tweedy figures who, with hammer and lens and acid bottle, had explored and observed and thought and written since the days when it was first realized that the earth is actually very old and that rocks are laid down with some natural purpose and that no deity had anything much to do with the actual manufacture of the planet—found their evidence for the theories and principles of the Old Geology in the rocks, fossils, faults and minerals that were scattered around simply and solely on the surface of the earth . They made crucially important discoveries, true; they laid the foundations for this most elemental of disciplines, true; but they did so by examining only the topmost layers—or at most the topmost few miles of thickness, if you will—of the planet.
    And that, it is now realized, was a very limiting way indeed of conducting the science—a science that, after all, should more properly be concerned with the nature and history of the earth in its entirety , and not with its surface alone. Before the 1970s we had knowledge about the earth’s outer cover and not much more. What we wanted to knowinvolved, if we thought about it, much, much more. We wanted to know—and geology was, in its theoretical essence, established purely so as to enable us the better to know—about the earth as a whole. And when the intellectual revolution of the sixties came about, we started swiftly to understand that up until that point we had, quite literally, only been scratching the surface; we had never considered the earth as it truly deserved to be considered.
    It promptly started to dawn on those sixties geologists who had listened to Tuzo Wilson or his acolytes, or who had seen the spacecraft pictures, that it was somewhat misleading for a science to draw conclusions about the earth entire by examining only those minor features that occurred upon, or just beneath, the planet’s outer covering. A fault in Scotland or the relic of a volcano in Montana or the succession of types of trilobite that had been found buried in a shale high on a hillside in British Columbia—such things might be interesting in and of themselves, but only when they were viewed in the context of the big picture, of the planet as a whole, were they able to offer up evidence that allowed the whole-earth portrait to be inked in and made to look something like complete.
    So this, then, lies at the heart of the New Geology. The world is these days viewed by most as one entire and immense system, the most refined of its details all interwoven with the biggest of big concepts. It is a living system four and a half billion years old. In a purely physical sense it is an entity warmed up from inside by radioactive decay, with fragments of its fairly recently cooled crust moving about on top of its more mobile inner self, and with solid rocks that have formed (or are still forming) on or beside these fragments creating continents or the floors of oceans. These rafts of solid rock have since been (or are still being) folded or lifted or broken apart as the plates on which they ride move about until they collide and bounce and dive beneath one another. In places, the rocks rise up to great heights; these are eventually eroded, causing the formation of sediment. Ageological cycle of creation and decay continues, endlessly. And meanwhile there is life, almost in global terms a brief irrelevance; animals and plants evolve and disappear by turns on the various wet or dry surfaces of theplanet according to a series of complex sets of rules that have been laid down by the practical realities of tectonics, of temperature, of pressure, and of almost limitless quantities of time.
    The finer details of these things have been studied for decades—such arcane niceties as the suture lines of ammonites (by which one can determine the species and subspecies of this particular beast, which floated gently about in the