Then the passage opened up. Not gradually but with a suddenness that must have shattered the composure of the first men digging into the cave. Jules Verne time, Anna thought, breathing a bit easier, and pushed herself to her feet.

A tunnel big enough for a locomotive led away to the southwest. "Tunnel," with its connotations of smooth walls and unhampered passage, was not the right word. The space Anna stared down was more a fantastical corridor, walls and floor and ceiling merging, growing together in rock outcrops and smooth pale beards of liquid stone, separating again, leaving behind delicate towers to reemerge into recesses maybe six feet deep, maybe going into the shadowed heart of the world for a thousand miles.

A path had been worn down through this cluttered basement of the desert. Orange plastic surveyor's tape marked both sides, the dirt between pounded and tracked. This surprising touch of humanity gave Anna back a morsel of control, and she felt the grip of muscles on the scruff of her neck loosen somewhat.

The trail wound through enormous blocks of limestone studded with rough grayish-white formations called popcorn, then vanished in darkness beneath a low arch in the rock. Though impressive, and the size a relief to her fear-tightened mind, the cave had no life and no color. In a land devoid of sunlight, color was superfluous. Everywhere the puny beam of her headlamp touched was gray or white or brown. The paucity of light circumscribed the area, making it no larger than the small circle illuminated, creating a sense of fragmentation that was disorienting.

In the world above, the memory of which was already fading, there were signs and portents, clues that let one know one was alive: breezes, birdsong and crickets, the sound of distant thunder, the smell of sage.