Where the Grand Silt Canal emptied into the broad expanse of the Great Silt Plaza, between Entry halls 086 and 090, the stone walls fell away into a huge underground lake.
This was the Grand Cross-hall. A circular reflecting basin four hundred paces wide, paved with slabs of white porous marble and enclosed by a tiered arena of eighty nested stone tiers that climbed eighty deep-water lengths toward the ceiling vaults. In ancient times, this basin had served as the central high-pressure surge-chamber for the entire vessel, capable of absorbing forty million gallons of sudden seawater shifted weight without flooding the upper residential halls. Its foundations rested directly upon the ancient dark rock ribbing of the Ark, anchored by four hundred fluted pillars that narrowed as they soared toward the darkness.
Beneath the water’s surface, the marble floor was carved with streaming drainage grooves, each groove cut three feet deep and lined with polished slate. These channels functioned as nonstop high-pressure scour-ways, directing any pooling silt outward toward the outer edge drainage drain pits so that the central mirror basin remained clear and free of mud.
Now, as the thousands of lanterns reached the mouth of the canal, the narrow river of flame swelled into a vast sea of floating fire.
