The boundary between fire and ice was not a gradual slope. It was a sheer upright cliff edge that plunged four hundred arm-lengths into the lightless gut of the world.
Qiao Ming stood on the lip of the shelf in Entry hall 855, his bare feet anchored to a ridge of frozen black glass. The glass was black glass, formed when white-hot magma had welled up from the deep-sea mantle and collided head-on with forty leagues of freezing ocean water. The surface was razor-sharp, fractured into crystal-clear terraces that gleamed with rainbow-bright peacock sheens in the gloom. But his calloused soles found purchase on the micro-ledges with gut certainty. Where an unpracticed foot would have been flensed to the bone, his wide, splayed toes gripped the glassy stone like horn.
To his right, thirty arm-lengths away, a hot-water vent roared with the force of a trapped storm. A geyser of white-hot steam and black stone water shot horizontally from a fissure in the cliff. It screamed as it snapped into the freezing updraft from the deep gap below. The heat differential was staggering: five paces to the left, ice crystals clung to the rock in thick, blue needles. Five paces to the right, the black glass was hot enough to scorch leather.
