A Crack in the Edge of the World Read Free Page A

Mesozoic seas), or the varying degrees of sphericity of the ooliths in a Jurassic limestone, or the patterns of those parts of bivalved creatures that are inelegantly known as muscle scars. But now, in the light of the whole-earth, big-picture view of the science of which they are so infinitesimal a part, they seem tangential to the broad realities of the New Geology, as the pores in an elephant’s skin do to a biologist or the volume of sap that courses through the leaves of a live oak from San Antonio does to a forest botanist.
    Which is not to say that such things are unworthy of our fascination. Small pieces of puzzles can often lead to grand ideas: The beaks of the Galápagos finches, after all, led Charles Darwin to his big notions about natural selection, the origin of species, and evolution. But it is important to remember that Darwin had at the time all of what was known of earth’s biology at his intellectual disposal—every beak and claw, every feather and fin was there, and his journeys took him to far and remote parts of our planet, so that he saw and thought about evidence from all manner of perspectives. When he sat down to write and think at his desk in Down House, he had an immense and almost unimaginable accumulation of information available to him, the finches’ beaks being just a scattering of tiles from the great mosaic of biological knowledge.
    But, by contrast, geology, at least before the 1960s, was able to lay out before its practitioners only the tiniest portion of available information—very little more than the superficial, the minute, the peripherally relevant. And then, in the nick of time (for without it, where would geology have gone?), everything altered: Along came the astronauts and the unmanned satellites and the space-born magnetometers and gravimeters and mass spectrometers and ion probes, and alongcame J. Tuzo Wilson and a whole army of like-minded tectonicists. They, combined with the new way of looking at the earth, taught the Old Geological community that there was much, much more to know—and what was once merely a hunch, an inner feeling, became a settled idea. It became abundantly clear that very few grand theories could actually ever be derived from minutiae such as ammonite suture lines and oolith sphericities and relative umbo sizes alone, except forensically; and that nowadays the grand geological ideas are the ones that truly matter.
T HE V IEW FROM O N H IGH
    And seen in that great and glorious context is the earth of the Californian morning of what Western Christian mankind had chosen to call April 18, 1906. Had any geologist at the time been able to look down at the planet in its entirety and witness what took place then, he would at the very least have been utterly amazed by the physical context of the event, even if the event itself, when viewed from on high, appeared less than overwhelming.
    For, as context, the planet would have been memorably beautiful. Had he been standing on the moon, say—had he been a 1906 version of Neil Armstrong, scanning with a hugely powerful telescope the surface of the blue and green and white ball that was hanging in his ink black sky—he would have seen illuminated in front of him (assuming that the cloud cover was not too dense) a tract of the world that extended from what some of mankind called India to what others called the Rocky Mountains, all of which would have been bathed in the brilliant white light of sunshine.
    He readily could have made out all of Europe and Africa, Asia Minor, and Arabia; he could have seen the deep blue of the Atlantic Ocean, the pure white mass of Greenland to its north, the blinding white immensity of the Antarctic deep below. The corpulent mass of what we now know as Brazil would have been sparkling in the sunlight, with the city-smudged eastern coasts of North America and Patagoniaonly slightly less so, places peopled with a humanity that was just waking on what many of