The floor ended not with a wall, but with a total, unplumbed void.
Beyond the Great Iron Arch, the dark rock avenue of Entry hall 300 narrowed to an eighty-pace stone jetty that projected outward into the gloom like the bowsprit of an anchored flagship. At the end of the jetty, marked by four massive bollards of cast sea-bronze, the stone simply ceased. Looking down past the edge of his bare toes, Qiao Ming saw only an expanse of pitch-black air that smelled of ancient fiery dark rock, crushed sulfur, and the huge, freezing chill of the deep hadal floor.
This was the Abyss Shaft.
It was an elliptical upright channel four hundred arm-lengths wide and two thousand deep-water lengths deep. It plunged directly through the heart of the Ark to the lowest keel-plates where the cold oceanic currents entered the thermobaric condensers. In the mythology of the first land-mappers, it was called the Well of Forgotten Depths. The central lung through which the sunken safe hall inhaled the cold and exhaled the warm mists that nourished the high ceiling clouds.
Qiao Ming stood at the western bollard, unslung his heavy pack, and laid out his sounding gear upon the dry flags.
