California is one of the newest parts of North America. Not long ago—just a couple hundred million years ago, which isn’t much on a geologic timescale—North America ended, roughly, in Nevada. To the west of Nevada was the Pacific Ocean, and in it, a great chain of islands that no longer exists. The island chain was inching its way east, towards Nevada’s Pacific coast. The islands crashed into North America, in succession, and coalesced into California. They left tectonic fissures—fault lines—as a reminder of their former independence. To understand what the islands looked like, pre-crash, “just look at a map of the southwest Pacific—look at the relationship between Australia and Indonesia right now.”
Those words come from Eldridge Moores, fourth in the line of geologists touring with John McPhee across the United States for McPhee’s five-part, Pulitzer-winning geological history of the United States, Annals of the Former World. Moores, we discover in the fourth installment Assembling California, comes from California rock stock; his father was a gold-miner near the Nevada border. “It was backbreaking work,” said Moores of his father’s bootstrap mining, “but my father had a tough back.”
