The final entry in McPhee's four-volume hymn to geology, known collectively as Annals of the Former World (most recently Rising from the Plains, 1986). Most of this volume appeared previously in The New Yorker. McPhee again displays his talent for explaining, without denaturing, technical matters that could make most heads reel. This time, he and geologist Eldridge Moores clamber around California and the Southwest, with junkets to Macedonia and Cyprus, to observe how the earth as we know it came to be. The investigation spans years; as it proceeds, McPhee makes geological obscurities simple and geological grotesqueries lovely. We see how pieces of earth fused to form California; among other things, this book is a Festschrift for the theory of continental drift--the idea that chunks of earth separate or collide, creating continents, mountain chains, gulfs. Moores reads road cuts like thumbprints; near the Donner Pass, he spots the outcropping of a quadrillion-ton chunk of granite humped under California. The 1848 California gold rush is detailed, a period when human time (measured in lifetimes) and geological time (measured in cons) conjoined, and yellow nuggets the size of shoe boxes fell out of streams. McPhee muses much on these two time streams, which also merge in the terror of earthquakes. The book's finest passage is a step-by-step retelling, as if in slow-motion, of the 1989 San Francisco earthquake, hideous in its eeriness ("In Asbury Heights, a man is watering his patch of grass. He suddenly feels faint, his knees weaken, and his front lawn flutters like water under wind") but doing nothing to postpone the dreaded Big One To Come. McPhee's overall lesson? That history is the bridesmaid of geology--and that the earth is a prankster. The author offers this wonderful testimony to the weirdness of plate tectonics: "The summit of Mt. Everest is marine limestone." Intolerable if one has no taste for mysteries beneath the soil; otherwise, riveting.