Basin and Range (Annals of the Former World Book 1)

by John McPhee

As the paleomagnetist Allan Cox, of Stanford University, would describe it in a book called Plate Tectonics and Geomagnetic Reversals, “The structure of the seafloor is as simple as a set of tree rings, and like a modern bank check it carries an easily decipherable magnetic signature.”

If it was altogether true, as Hess had claimed, that with relative frequency “the whole ocean is virtually swept clean,” then old rock should be absent from deep ocean floors. Since 1968, the drill ships Glomar Challenger and JOIDES Resolution have successively travelled the world looking for, among other things, the oldest ocean rocks. The oldest ever found is Jurassic. In a world that is 4.56 billion years old, with continental-shield rock that has been dated to 3.96, it is indeed astonishing that the oldest rock that human beings have ever removed from a seafloor has an age of a hundred and eighty-five million years—that the earth is twenty-five times as old as the oldest rock of the oceans.

“The entire history of Nevada is one of plant life, animal life, and human life adapting to very difficult conditions. People here are the most individualistic you can find. As district attorney, I see examples of it every day. They want to live free from government interference. They don’t fit into a structured way of life. This area was settled by people who shun progress. Their way of life would be totally unattractive to most, but they chose it. They have chosen conditions that would be considered intolerable elsewhere. So they would adapt, easily, to the strangest of situations.”