The Grand Canyon is losing its river

(Left) Just one small section of the huge rift in the Earth’s crust that forms the Grand Canyon.

DOWN beneath the tourist lodges and shops selling keychains and incense, past windswept arroyos and brown valleys speckled with agave, juniper and sagebrush, the rocks of the Grand Canyon seem untethered from time. The oldest ones date back 1.8 billion years, not just aeons before humans laid eyes on them, but aeons before evolution endowed any organism on this planet with eyes.

Spend long enough in the canyon, and you might start feeling a little unmoored from time yourself. The immense walls form a kind of cocoon, sealing you off from the modern world in the United States beyond, with its cell signal and light pollution and disappointments. They draw your eyes relentlessly upward, as in a cathedral.