Beyond the dynamic cross of the Upper Siphon lay the Concourse of Roots—the massive deep-rock highway where the twelve sovereign taproots of the Dawn-Redwood came together into a single, braided column of stone-hard timber dropping into the depths of Entry hall 650.
The scale of the concourse was staggering. Each of the twelve roots was fifty paces in width, twisted together like the huge strands of an anchor-cable forged for a sky flagship. The timber was not ordinary wood. It had stone-hard under uncounted thousand years of deep water pressure into black hornstone and jade lignite, polished to a slick, glassy luster by the unending water drops of the deep drafts.
Between the braided trunks ran deep, fluted canyons thirty paces wide, along which the drainage waters of eighty entry halls rushed in foaming, azure torrents. The air here was hot, thirty-two degrees, heavily charged with stone steam and the increasingly pungent stench of the Iron Seep.
The sound environment had undergone a deep shift. The soft vegetative rustle of the upper canopy was entirely absent. In its place was a nonstop, ringing drone that traveled directly through the stone-hardened fibers of the wood, humming like a huge cello string stretched across a mountain gorge.
