GRAND CANYON

How did the Grand Canyon come about? Geologist Powell strives to give the latest accounting, but he’s torn between addressing a popular audience and spinning out all the geological theories.

When geologists first laid eyes on the canyon, it was love: here, the Earth would reveal the deep secrets of its structure. But the great fissure would prove far from a cheap date. Throw me a theory, buster, it would say, and I’ll throw you back a curveball. Powell starts, and continues for over half of his pages, with biographical sketches of the early geologists—John Newberry, John Wesley Powell, Grove Karl Gilbert, Clarence Dutton—spelling out in simple terms the nature of their theories (through they were by no means simple, including abrasion, transport, and stream morphology—early glimmerings of the fluid interior of the planet). By the time geologists Charles Hunt and Edwin McKee enter the picture, the theories get more tortured, the academic beard-pulling starts, and Powell (Night Comes to the Cretaceous, 1998) begins losing the less devout rock hounds as he enters the dark matter of advanced geology. Those who do wade through the material will experience the feeling of watching a fascinating chess game only to have it end in a draw: None of the theories, painted in such detail, has ever been proven. Ultimately, Powell suggests that the best modern theory combines “large-scale drainage reversal, headwater erosion and stream piracy, possibly aided by lake integration”—and it’s a tribute to him that lay readers will understand all those terms—but what many readers will walk away with is a sense of the awesome power of water running over the surface of the earth.

Powell warns at the outset that the canyon may be on naked display, but that doesn’t mean it’s not deeply complicated: as many theories litter its banks as rapids break its water. (Photographs, maps, diagrams)