The retreat of the seventh tide transformed the huge floor of Entry hall 107 into a shining, lightless expanse of black mud.
The basin stretched four hundred paces between the huge pillars of the Lower Scroll hall, a sunken gallery where ancient scholars had once deposited the settled mud filtered from the upper freshwater channels. Over hundreds of years of undisturbed settling, the silt had formed a uniform bed two arm-lengths deep. A dense, velvety slurry of crushed shale, decomposed river-kelp, and tiny stone mica as smooth and slippery as cold mutton fat.
Under ordinary conditions, the surface of the silt appeared deceptive. A flat, glistening crust of gray-black mud that reflected the pale light of the high window row windows like dark black glass. But beneath that crust lay a thixotropic trap. Left undisturbed, the silt held the consistency of soft butter. Agitated by rapid footsteps or the heavy, packed weight of iron boots, its atom-deep bonds broke down instantly, transforming the mud into a bottomless liquid that swallowed anything heavy before resetting into a vice-like gel around the trapped intruder.
Qiao Ming stood at the edge of the northern flat stone slab apron, his bare feet caked with a light film of gray slime. He held a sounding pole of dried bamboo, five deep-water lengths long, testing the depth of the settled mud along the marginal channel. Beside him rested three broad mud-skiffs. Flat rafts made of bundled dried reeds, four feet wide and eight feet long, upon…
