The town of Page came into being, along with the Glen Canyon Dam, in the late 1950s. It is located within the Navajo lands that occupy most of northern Arizona, and it serves as the staging area for tours of several mysterious and magical cracks in the earth's surface. These so-called "slot canyons" are cuts, eroded over millions of years, through sandstone laid down when what is now a mile-high plateau was the floor of a plesiosaur-infested sea. You would guess, perhaps, that flowing water would simply cut a straight gouge, like a saw, or a V-shaped notch, like a chisel; or, at the most, that it might indulge in a few graceful meanders. Luckily, you would be wrong. Instead, it twists and turns, shuttling side to side and up and down or spiraling dizzyingly, its own cargo of abrasive particles scouring away the rock in fantastic shapes. Strata, stria, humps and hollows, tongues and hips, billows and swirls - the whole vocabulary of cloud formations, familiar to pilots, and countless other undreamed-of things, are here set forth in stone. Exposed to oxygen, the sandstone surface colors; intermittent light filters in from above - slots may be 50 yards deep and only a yard wide - in pencil-like beams and meandering glows that suffuse the eerily sculpted passages, while your feet tread orange sand as fine as flour.