Half a league below the southern portal, in the narrow, wind-swept gorge of Entry hall 645 known as the Upper Siphon, the nonstop root-highway came to a sudden, total termination.
Here, during the ground-shaking upheavals of the Third Dynasty, a massive earth-shaking shear had torn the eighth and ninth root-arteries apart. That left a sheer, yawning void forty-eight paces wide between two straight-across cliffs of stone-hard dark wood.
Far below the gap, through swirling ribbons of white stone vapor and sulfur smoke, the black drainage clouded eye roared as it plunged into the bottomless depths. A single misstep here meant falling three thousand deep-water lengths without touching a ledge. The walls on either side were sheer, polished to a glassy slickness by uncounted hundreds of years of acid spray, offering neither handhold nor crack for iron pitons.
The deep gap acted as a huge chimney, funneling the boiling sky discharges of the lower foundries upward into the cool air of the mid-depths. The air shrieked through the bottleneck like a nonstop organ pipe, shaking with churning shear-eddies that tore at the edges of their moss mantles.
Across the void, eighty yards away, lay the broad, moss-covered landing of the main Concourse of Roots—the only avenue leading down to the grand round hall of Entry hall 650. But between the two ledges hung only empty air, buffeted by a violent, pulsating heat draft that rose at thirty knots from the Abyssal Foundries below.
